Final Report Summary - PLA4FOOD (Active Multilayer Packaging based on Optimized PLA formulations for Minimally Processed Vegetables and Fruits.)
Executive Summary:
PLA4FOOD proposal dealt with the development of innovative active and biodegradable packaging for fresh-cut food products based on renewable resources thermoplastic materials (PLA-polylactic acid) functionalised with the synergic addition of additives from natural sources (antioxidants, antibacterial and antifungal) in order to increase the shelf-life of packed products.
Different encapsulation routes were tested to protect active additives from processing conditions and to have controlled migration rates. Additionally, to minimize PLA current limitations in flexibility, water barrier properties and processability different additives were studied including bio-based lactic-acid plasticizers, inorganic nanofillers and organic nucleants.
The main application for these new active packages is the fresh-cut products packaging, specifically prepared and washed fruits and vegetables packaged without additives or preservatives in the food itself. These additives are currently added with the aim of achieving a minimum time of preservation of 7 days.
To develop this innovative active and biodegradable packaging to increase the shelf life of fresh-cut food products, several activities were carried out, focused in the following work areas:
- Studying the antimicrobial, antifungal and antioxidant effectiveness of natural selected active additives in several fresh cut products.
- Studying of different encapsulation technologies in order to protect active additives from processing conditions and allowing controlling their migration speed.
- Minimization of the current PLA limitations related to flexibility, barrier properties and processability.
- Obtaining of multi-layer structures from different PLA formulations, by means of diverse co-extrusion techniques (blown-film and cast-sheet and thermoforming) with the aim of getting the best cost/benefit ratio, and the optimum development of the active package through each layer’s thickness and crystallinity.
Project Context and Objectives:
Co-extrusion techniques (blow-film and cast-sheet and thermoforming) were developed to obtain multilayer structures from different PLA formulations, in order to achieve the best cost/benefit ratio and optimal performance of the active packaging by controlling the thickness and crystallinity of each layer.
First, it was defined the requirements for the active packaging to be developed for three specific fresh-cut products: salads, green vegetables and fruits. It has been defined and also the materials, additives and packaging process for each case study. The materials selected for the new package manufacture are at least a 95% from renewable resources.
It is studying the effectiveness of natural selected active additives in the three selected fresh – cut products and designing and optimizing encapsulation technology for antimicrobials, antifungals and antioxidants for the manufacturing of PLA based active packaging. Three additives were selected due to their antimicrobial, antifungal and antioxidant activity.
To optimize the outer layer, it is working in the improvement of PLA flexibility using different oligomeric lactic acid plasticizers (OLA). It was selected the most suitable one and the better concentration to obtain the flexible and rigid packages.
Water vapor permeability of the material was improved by the incorporation of scavenger to control the humidity into the package. It was selected the most promising filler and the better concentration. Currently it is optimizing the equipment and the process parameters.
The inner layer of the package will be the active system of the package where the antibacterial, antinfungal and antioxidant selected must migrate from the package to the food at a specific rate for each selected fresh-cut food.
To develop this inner layer it is currently developing the different blends of PLA with the encapsulated active additives by compounding process.
To develop the whole project, several processes were optimised:
Capsule formulation and production
During the project, several types of additives were employed. Garlic molecule was selected as an active additive encapsulated in inorganic and porous filler to protect it against the compounding process conditions (temperature and shear); sepiolites to improve the water vapour permeability of the package, and plasticisers to obtain better mechanical properties and to improve the material processability.
Based on the data obtained in the first period of the project, optimization of the capsule was done by means of re-formulation, in order to achieve the optimal methodology for the microcapsules processing.
The garlic which accommodates the inorganic fillers microcapsules is equivalent to 7% of the microcapsules total weight. From this garlic molecule load, it was lost 30% in the inorganic filler capsules during the first 14 days at 25°C. At 4°C we lost 30% in the inorganic filler capsules.
Considering these results and different parameters of optimization of the capsule formulation it was optimised protocols for microcapsules production and storage. These protocols allowed the incorporation of the required amounts of the active compounds in small capsules, and defined the conditions for slow release in order to keep the compounds in the capsules until they are added to the films.
Compounding process
According to the case studies selected and the Annex I, two different grades of PLA were used along the project. One PLA grade used for cast sheet extrusion and another PLA grade suitable for blown film extrusion applications. Since the crystallinity and behaviour of the two PLAs were different, several plasticizers were proved to check the efficient to improve PLA properties.
Two PLA grades from the company NatureWorks (USA) were selected. The tested new plasticizer for this work package was an oligomer lactic acid type, to increase the compatibility with PLA. A commercial grade of Lapol company from USA was used.
To achieve an optimal dispersion of the new plasticizers in the PLA matrix by extrusion, a suitable screw configuration designed for the optimal masterbatch production was used.
To avoid hydrolytic degradation of the biopolymer PLA and the biobased additives a venting system was used to remove water during compounding. The venting system consists of an atmospheric and a vacuum degassing unit.
The processing of plasticised is limited due to the sensitive of the resin to heat and thermal treatment. Re-melting plasticiser resin more than three times may result in gelling and compromise properties.
Multilayer blown film and cast sheet manufacturing
The objective was to optimize the processes parameters to obtain a multilayer structure without interfacial instabilities and encapsulation problems.
The following aspects of each multilayer configuration has been controlled and optimized:
• To optimize processing temperatures’ profiles of each extruder.
• Speed of extrusion in each extruder. This parameter offers us the adequate residence time that will allow the material to flow with the right viscosity.
• The thickness of each layer obtained according to the material’s properties and extruders output to avoid problems of flow and/or interface instabilities.
The thermal, mechanical resistance, thickness distribution and homogeneity was used as control parameters.
It was optimised the multilayer structure by reducing the thickness in the functional layers (with water scavengers and inorganic fillers) in order to minimize the cost.
The ratio between the layers was adjusted to avoid interfacial defects, and the total thickness was the suitable to be thermoformed according to the depth of the tray selected to pack the food in the industrial scale-up, and to obtain a tray with good mechanical properties.
Packaging process
The sheets obtained were thermoformed to obtain the rigid package (trays) and the films developed were used to obtain the flexible packages (bags) and to close the trays.
The films and sheets obtained in the project showed good properties and they fulfil the requirements established. The new developed packages showed high flexibility and good barrier properties compared with the commercial grades by the effect of the additives added.
The packages developed are suitable to be in contact with fresh cut food according to the overall migration analysis performed and they are fully compostable.
Project Results:
As a result from the combination of advances material science and improvements in processing technologies, an active and biodegradable package from renewable sources it is being developed. This packaging has applications in the food industry, and provides products with protection against environmental agents, improvements in the preservation of the packaged product’s properties (quality, shelf life, microbiological safety, and nutritional values), but also being biodegradable under compostability conditions, according to the UNE-EN 13432 European standard.
The main achievements fulfilled with the PLA4FOOD project development are summarized below:
1. The processability of the materials developed was optimised to obtain the final package with active additive-garlic. It was obtained a three layer structure by cast-sheet and blown-film extrusion.
2. The multilayer sheets adapted perfectly to the pilot plant thermoforming machine and copied all the details from the mould and the multilayer films are suitable to be used in VFFS machines.
3. The migration of the garlic to the food products was demonstrated to be effective. While garlic molecule was stable in the capsules and films before packaging it was showed that the active compound (up to 40%) is released to the food within 9 days in the presence of the vegetables.
4. The PLA packages preserve the vegetables and improve the product quality. These results suggest that the PLA packages indeed may act to prolong the shelf life of the different types of leaves.
5. Related to the antimicrobial activity of the PLA package, it was found a microbial reductive trend for all of the PLA packed vegetables; it can be pointed towards the possibility of the PLA package which act to preserve the vegetables by a partial bacterial growth inhibition.
6. The benefits of the PLA package with the garlic capsules was observed even in cases that only PLA lids were used.
7. Altogether the PLA package was proved to be functionalized with the garlic by controlled migration rates and to improve the product properties (quality, shelf-life, hygienic).
8. The kinetic of the garlic release without vegetables differs from the release with vegetables, and is also affected by the vegetable type.
9. The target mechanical properties required for the films and sheets were fulfilled using the materials developed in the project.
10. An improvement in the water vapor barrier properties of the samples manufactured was obtained when compared to the commercial PLA.
Next it is showing the results highlighted from each WP.
WP 1. Definition of requirements, case studies and selection of additives and materials
1.2.- Summary of progress towards objectives and details for each task;
The WP1 main objective was the definition of the requirements for the active packaging to be developed for three specific fresh-cut products.
The three typologies of products: salads, green vegetables and fruits have been defined and also the materials, additives and packaging process for each case study.
The materials selected for the new package manufacture has more than 95% from renewable resources.
1.3.- Highlight clearly significant results;
Case studies selected are summarized in table 1.
Table 1 Case study selected
1 Salad – Iceberg lettuce Package: Flexible Film/sheet producer: ALESCO Package producer: STRAUSS Active additive:Antibacterial
2 Salad – Romaine lettuce Package: Rigid Film/sheet producer: POLYRAZ-tray
ALESCO-lid Package producer: STRAUSS Active additive: Antibacterial
3 Green vegetable – Beet leaves Package: Flexible Film/sheet producer: ALESCO Package producer: STRAUSS, Active additive: Antibacterial and antioxidants
4 Fruit – tomato Package: Rigid Film/sheet producer: POLYRAZ-tray
ALESCO-lid Package producer: TROYKA Active additive: Antifungal and antioxidants
The different requirements of the new package have been defined:
• The co-extrusion (film and sheet) and thermoforming process parameters: industrial equipment available in the partners companies, dimensions of the film and sheet, melt temperatures, output and residence time between others.
• Finishing packaging process needed: thermoforming and packaging process regarding equipment, mould and film dimensions, sealing conditions,...
• Other issues regarding filling process, transport and conservation conditions.
• Recycling process in order to study the re-processability of industrial scrap or post-consume packages o establish if the recycled material may be incorporated with influencing in loss of new product properties.
Selection of natural antimicrobials, antifungal and antioxidant additives.
The most suitable additives according to the selected food and the process parameters were selected.
Selection of PLA grades and flexural PLA modifiers.
From the PLA grades review, the most suitable for the project development are supplied by NATURE WORKS. It were selected two different grades, one for rigid packaging applications and another for flexible packages.
Further additionally additives were necessary in order to improve the PLA processability and properties:
o Plasticizers. The most compatible with PLA is OLAs to minimize the migration and to improve the miscibility.
o Water scavengers. The most suitable are sepiolites. It was selected a sepiolite with the proper surface modification to increase the PLA compatibility.
o Organic nucleants. It was selected several nucleants from different suppliers, with another function, as an impact modifiers or melt strength enhancer to improve the material properties.
WP2. In vitro study of additives effectiveness over the food. Microencapsulation of selected additives.
1.2.- Summary of progress towards objectives and details for each task;
The goal of WP2 was to study the effectiveness of natural selected active additives in the three selected fresh – cut products and design and optimize encapsulation technology for antimicrobials, antifungals and antioxidants for the manufacturing of PLA based active packaging.
Study of the “in vitro” activity of the selected antimicrobials, antifungal and antioxidants.
An initial experiment was conducted to evaluate the microorganism populations on these fresh vegetables and a comparison was made with EC and Israeli regulations. Cut Iceberg leaves and beet leaves were found to contain high levels of coliforms. 108 samples of beet leaves were evaluated with a mean value of 280,000 cfu/gr, and 40% of samples contained coliforms above 100,000 cfu/gr. The coliform counts increase significantly around the mid-period of shelf-life (after day 6).
The active antimicrobial additives selected by DOMCA were: Propyl Propene Thiosulfonate (PTSO), Synthetic mustard oil (Allyl isothiocyanate), Tetraene polyene macrolide (Natamycin) ,and Bacteriocin DMC, Eugenol. Antimicrobial activity of all 5 compounds was assessed ‘in vitro’ against microorganisms that were purified from each product (at least 6 microorganisms from each product). Compounds PTSO, Synthetic mustard oil and Eugenol showed high activity against standard (ATCC strains) and against a wide variety of microorganisms (mezophilic-aerobic, coliforms, lactic acid bacteria, yeast/mold) we had isolated from the food products. Eugenol was active against all microorganisms with MIC bellow 0.1 g/L, and the other compounds had MICs of 0.16 or less. Compounds 3 (Natamycin) and 4 (DMC bacteriocin) showed little or no activity against all types of bacteria tested.
The activity of the antimicrobial additives PTSO, Mustard oil and Eugenol against microorganisms on the products was investigated by dipping the product in water solutions containing different concentrations of the active compounds. These experiments were done using Beet leaves, Iceberg lettuce and Cherry tomatoes. All compounds used were efficient against the different groups of microorganisms on the different products. Washing with the lower concentrations were less effective, but usually resulted in at least 2-log reduction. In low concentrations (0.1%) PTSO showed the most efficient antibacterial activity against coliforms in all the vegetable, with the most significant reduction exhibited in beet leaves. In high concentrations (1% and above) PTSO and Mustard oil exhibited high antimicrobial potential. All three active compounds were effective against coliforms on cut Iceberg leaves and on tomatoes. Eugenol showed high antibacterial activity on tomatoes as well. When high concentrations were used significant color changes were seen on the cut lettuce leaves, while the lower concentration (0.1%) did not alter the leaves color. All compounds showed an efficient antifungal activity in tomatoes.
In order to assess the activity of the additives: PTSO, Mustard oil and Eugenol, a shelf life experiment was conducted on the selected fresh cut products. The antimicrobials were diluted to different concentrations and spread on the inner parts of the current (PE and PP) package sheets. Microbial counts were measured during shelf life. Results of the microbial counts showed that PTSO had an efficient antibacterial activity against all microorganisms. However, the shelf-life was not increased. The compound significantly damaged the leaves which a distinct color and structure change, loss of water and had become soft.
When cut leaves of Iceberg lettuce were examined for the antimicrobial activity of the additives it was seen that at high concentrations of Mustered oil had a high antimicrobial activity, particularly against coliforms, followed by Eugenol, which usually had better activity against lactic acid bacteria. All compounds had good activity against yeasts, which exists in very low levels on the selected products. In lower concentrations (≤1%) the antimicrobials were not significantly effective, but in some cases still damaged the leaves before the end of the products shelf-life. In order to understand if the continues exposure to the antimicrobial has impact on the products damage during shelf life, an additional shelf life experiment was conducted with the selected food products. In this experiment the vegetables were pre-washed in a solution containing the antimicrobial additives. Pre-washing of beet leaves with all active compounds (1%) had resulted with very low microbial counts at the end of the products shelf-life. The lower concentrations of the active additives (0.1%) did not show significant antimicrobial effect and the bacterial counts results were similar to the controls. Nevertheless, pre-washing with all active additives (0.1-1%) had resulted with spoilage of the product before end of shelf-life. Similar results were observed when cut Iceberg lettuce samples were pre-washed with PTSO (1%) and Mustard oil (1%). The tomatoes shelf life results showed that 1% of Mustard oil had reduced the bacteria dramatically while the changes in tomatoes appearance were negligible.
In order to study the effect of the additive compounds in very low concentrations a new shelf life experiment was conducted. The concentrations used in this experiment were too low for antimicrobial activity, but still enabled to maintain some antioxidant activity and probably other activities (such as inhibition of enzymatic activity) that may impact the products quality.
The definition of the shelf life of these fresh cut products is: ‘the product will be disqualified for marketing if more that 20% of the leaves are spoiled or oxidized‘(Strauss). All leaves that had shown a color change were considered to be oxidized and were disqualified for marketing. After administering the active materials to the food products fewer packages were disqualified as compared to untreated packages. When using PTSO only 17 packages were disqualified as compared to 42 without the treatment. Mustard oil had improved shelf life for 20% more packages as compared to the control. It can be concluded that PTSO and Mustard oil in low concentration of 0.001 and 0.0001 (gr/Package of 100 gr leaves), respectively, had been able to increase shelf-life of leaves, probably by antioxidant activity.
From the study of 5 natural active additives, provided by DOMCA, it was concluded that PTSO (garlic), Synthetic mustard oil and Eugenol (clover) showed a broad range of activities against gram positive and gram negative bacteria presented in the food products, including coliforms and E. coli, and against eukaryotes (yeast, mold) as well. Moreover, PTSO and Eugenol also have antioxidant activity. Since the activity of the additives changes in the different products (cut lettuce leaves, beet leaves and cherry tomatoes), the two most suitable additives for each of the food products were defined. PTSO and mustard oil usually had the best activity. For that reason work was focused on production of microcapsules with both additives. However, some preliminary experiments were also conducted with Eugenol. The approximate range of optimal concentrations of each type of additive for each type of food that expected to maximize the shelf-life of the packed product was also determined. This was based on the fact that the antimicrobial compounds were found to be very active in solution but have only limited antimicrobial activity when they were spread on the packaging sheets, and in high concentrations it was paralleled with a significant decrease in the quality of the products.
Study and development of microcapsules.
The aim of this step was to create the starch-active additive (PTSO, Mustard oil and Eugenol) microcapsules in a pilot scale with a continuous process that will be suitable for scale up for the industry, as well as for the preparation of large samples for product formulations, testing, and in-vivo experiments. In order to form sub micron capsules, the process has been performed using dual feed jet homogenizer.
Zeolite is a hydrophobic crystalline aluminosilicate with a network of channels and cavities with pore diameters in the range of 0.7-1.2 nm. It has a high thermal, mechanical and chemical stability that can be transferred to the encapsulation additive. The production of Zeolite-active additive (PTSO, Mustard oil and Eugenol) microcapsules was carried out in bench-top scale but can easily be converted to a continuous industrial process.
Thermal stable microcapsules containing active additives were developed and design and defined the microcapsule coatings, process of development and load. Zeolite and starch based microcapsules were developed.
Characterization of the capsules.
Light microscopy and SEM images were obtained in order to gain information on the aggregates size and morphology. All HACS microcapsules aggregates have a large population of very small particles (less than 5 µm) and bigger aggregates.
From the SEM images it is evident that there are morphological differences between the three microcapsules. Their shapes are not uniformed, amorphous and highly porousive. HACS-PTSO and HACS-Eugenol have similar pours or cavities shapes as compared to HACS-Mustered oil which have smaller pours but are more clustered.
Particle size analysis was performed by laser diffraction sizing of particles. A typical size analysis for HACS microcapsules samples showed a collection of aggregated sub-particles. The volume weighted mean average of the particles was ~ 8 µm and surface weighted mean average was ~6 µm. The industrial PLA packaging process requires an average particle size of ~ 5 µm. These microcapsules reversible aggregates contain single particles in the sub-micron size level that fit the size required criteria.
DSC was applied to test the thermal properties and dissociation temperatures of starch-active additive complexes. A DSC analysis was conducted to simulate the PLA packaging process. In this analysis we had attempted to simulate the temperature profile of the extruder processes used for the compounding of the PLA, film production and thermoforming of the PLA trays. From the results obtained for HACS –active material microcapsules, it is apparent that no significant thermal event has occurred during all 3 heating stages. The starch based microcapsules showed thermal stability throughout the analysis with no indication of any thermal event or melting event.
The objective of this task was to incorporate the maximum amount of bioactive ingredient in the capsules. In order to find the best encapsulation formulation three active materials (PTSO, Mustard oil and Eugenol) were encapsulated in starch (HACS) and Zeolite and a the microcapsules contents were established. HACS microcapsules showed a higher load content when PTSO was encapsulated as compared to the Zeolite microcapsules. Similar content results in both microcapsules were obtained when Mustard oil and Eugenol were encapsulated, ~2% and ~6%, respectively.
Capsule size was evaluated by microscopy or particle size analyzers. Morphology was studied by SEM. Thermal stability was evaluated to simulate processing conditions. The kinetics of the release of the bioactive was evaluated by following the bioactive content in the capsules along simulate storage conditions.
Based on the data obtained in the first part of the WP, optimization of the capsule by means of re-formulation was done, in order to achieve the optimal methodology for the microcapsules processing.
1.3.- Highlight clearly significant results;
The goal was to study the effectiveness of natural selected active additives in the three fresh-cut products and design and optimize encapsulation technology. During the first 9 months, Microbial tests with the 5 antimicrobial compounds obtained from DOMCA have been conducted by TECHNION in order to determine the best compound properties, additionally it has been found that the three compounds had an excellent antimicrobial activity in vitro and in vivo, unfortunately the compounds also hurt the fresh-cut products, and thus did not increase the shelf life in the range of concentrations that gave the optimized antimicrobial activity.
- The Beet leaves are the most sensitive product to microbial growth, and cut lettuce leaves are more sensitive than intact leaves.
- Antimicrobial activity of the selected additives should focus on coliform counts.
- Compounds: PTSO, Mustard oil and Eugenol showed more efficient antibacterial activity as compared to Natamycinand and DMC bacteriocin which showed little or no activity against all types of bacteria tested.
- In some shelf life tests the antibacterial activity was paralleled with a significant decrease in the quality of the products.
- The results showed that mold and yeast were not a significant problem in the 4 selected food products.
- Based on the results of the experiments described above the following additives are suggested for each of the food products:
• Cut Iceberg leaves: PTSO, Mustard oil
• Beet leaves: PTSO, Mustard oil, Eugenol
• Tomatoes: Mustard oil, PTSO
- Optimal concentrations of each type of additive for each type of food that maximizes the shelf-life of the packed product:
Cut Iceberg leaves: PTSO (~0.001 gr/package of 100 gr), Mustard oil (~0.0001 gr/package of 100 gr)
Beet leaves: PTSO (~0.001 gr/package of 100 gr), Mustard oil, Eugenol (~0.0001 gr/package of 100 gr)
Tomatoes: Mustard oil (~0.01 gr/package of 100 g), PTSO (~0.001 g)
Experiments conducted to achieve the goals of Task 2.1 have been completed.
1. Starch based and zeolite microcapsules were developed for the encapsulation of antimicrobial, antifungal and antioxidant active additives.
2. Starch based microcapsuled showed thermal stability in simulated PLA processing conditions.
3. Starch and Zeolite microcapsules fit the size criteria established for the PLA processing conditions.
4. Starch and Zeolite microcapsules have similar load contents when encapsulating Mustard oil and Eugenol.
5. Starch microcapsules showed better encapsulating ability when PTSO was loaded in the capsule compared to Zeolite.
Considering the different parameters of optimization of the capsule formulation, it was recommended on PTSO encapsulated in HACS (starch) or Zeolite X (CECA S.A) or Mustard Extract encapsulated in Zeolite X (CECA S.A).
WP3. Development of PLA compounds with improved performance for the outer layers
1.2.- Summary of progress towards objectives and details for each task;
Formulations of PLA with oligomer lactic acid plasticizers.
In order to improve the flexibility of PLA, different oligomeric lactic acid plasticizers (OLA) were prepared by using a strand pelletizing process consisting of a co-rotating twin-screw extruder with degassing units and side-feeder (for the feeding of plasticizers). The changes in flexibility by using the plasticizers from company Futerro (Belgium) are very small. Even at the highest amount of OLA plasticizer the E modulus was not influenced and the elongation was decreased. The suitable OLA plasticizer to improve the flexibility of PLA is OLA8 (Condensia, Spain) and Lapol 108 (Lapol, USA). The advantage of Lapol 108 plasticizer is the availability of a masterbatch, for better dosing and feeding. The effective dosage of Lapol 108 to obtain flexibility is lower compared to OLA 8 plasticzizer. The E modulus and the tensile strength were significantly decreased, the elongation increased. All plasticized PLA compounds show no reduction in transparency up to 20 wt.-% Lapol 108, they were miscible with the selected PLA grades PLA2003D and PLA4032D from NatureWorks (United States). The heat deflection temperatures (HDT) of all plasticized PLA compounds were lower than the HDT of pure PLA. The flow behaviour of plasticized PLA2003D and PLA4023 are very similar. The changes in the mechanical and thermal properties are also similar. The only difference between these compounds was the higher reduction in tensile strength and E modulus for the grade PLA2003D.
Development of plasticized PLA compounds with increased the thermal resistance by using organic/inorganic nucleants.
The effect of improving the mechanical properties of plasticized PLA by nucleation is not only depending on the amount of the nucleating agent. The main factors are the process conditions and the selected process. In the injection moulding process with higher tooling temperature (100 °C) and long residence time (180 s) of material in the mould enhanced mechanical and thermal properties were obtained. The plasticized PLA compound with nucleating agents was also more flexible. The tested nucleating agents were SUKANO PLA na S516 from Sukano AG (Switzerland) and CN-L01 Polyvel, Inc. (USA).
To transform these results from the injection moulding process to film manufacturing (blown film, cast film) and thermoforming process additional test will be carried out.
Development of PLA compounds for the outer layers.
a) Plasticized PLA and sepiolite
A suitable method to incorporate sepiolite clay in a plasticized PLA is to produce a sepiolite masterbatch (15 wt.-% sepiolite) and to dilute it to the required amount. Two batches of plasticized PLA with sepiolites grades S-20 and S-80 from company Tolsa (Spain) were provided to AIMPLAS for film and sheet manufacturing. The measurement of the water vapour permeability (WVTR) is still in process.
b) Plasticized PLA masterbatch
A masterbatch with a loading of 40 wt.-% OLA8 in PLA2003D was produced. After a drying process the granules were not sticky and show no transparency. This plasticized PLA masterbatch can be diluted easy to the required OLA plasticizer level for using in food packaging applications. This masterbatch will be diluted to adapt the OLA percentaje round 20 % showing an adequate transparency.
c) Design of experiment (DoE)
To conduct the DoE method different data and information were collected.
The effect of different additives on plasticized PLA were studied. The effect of the applied additives in plasticized PLA shows no significant changes in the tensile properties at the used additive level. The effect of specific mechanical energy (SME) on the properties of plasticized PLA was only significant for the OLA8 plasticizer. No changes in the mechanical properties were obtained by using the grade EP0005 at different SME values. For good dispersion of plasticizer in PLA a suitable OLA grade and high SME is required.
Production and characterization of the different monolayer films and sheets.
The compounds developed have been processed on a pilot plant monolayer extrusion line to produce sheets (extruder + die + cooling roll + calendar). With the rheological and mechanical data, the parameters for the extrusion to be optimized are the temperature profile, speed of extrusion, screw design and stretch ratio. Also, die design and roll temperature must be studied.
The use of masterbatch requires paying special attention in the selection of the screw extruder in order to reach a high level of dispersion of the additives embedded in a low viscosity PLA matrix. The produced films were characterized by a) thermal analysis, b) mechanical methods and c) permeability analysis.
1.3.- Highlight clearly significant results;
The suitable plasticizer to improve the flexibility of PLA is Lapol 108 (Lapol, USA). All plasticized PLA compounds show no reduction in transparency up to 20 wt.-% plasticizer.
Using nucleating agents leads to an improvement in (injection moulded parts):
- Heat deflection temperature (HDT) from 39 °C to 44 °C
- Notched impact strength from 1.6 kJ/m2 to 3.0 kJ/m2
a) The incorporation of sepiolites in plasticized PLA compound is possible via a masterbatch route.
b) A masterbatch with a loading of 40 wt.-% OLA8 in PLA2003D was produced.
c) The effect of additives, recommended for PLA applications, in plasticized PLA (9 wt.-% OLA8) shows no significant changes in the tensile properties at the used additive level.
Using the nucleating agent Lapol HDT leads to an improvement in (injection moulded parts, PLA4032D, 20 wt.-% Lapol HDT, 15 wt.-% Lapol 108):
- Heat deflection temperature (HDT B) from 52 °C to 64 °C
- Notched impact strength from 1.8 kJ/m2 to 3.7 kJ/m2
- Elongation from 2.6 % to 7 %
The measurement of the water vapour permeability (WVTR) will be performed with the optimised film sheet obtained.
The incorporation of sepiolite S 80 (Tolsa) in plasticized PLA compound is feasible via a masterbatch route. The optimal process conditions for good dispersion of sepiolites particles in PLA matrix is a high specific mechanical energy (SME) intake.
A masterbatch with a max. loading of 30 wt.-% Lapol 108 in PLA2003D and PLA4032D was produced. Four different PLA compounds are available for film or sheet production:
- PLA2003D with loading of 20 and 30 wt.-% Lapol 108
- PLA4032D with loading of 20 and 30 wt.-% Lapol 108
Production and characterization of the different monolayer films and sheets.
The glass transition temperature Tg of all plasticized PLA compounds were about 60 °C.
Improvement of 440 % in elongation of plasticized PLA (loading 18 wt.-% Lapol 108) was obtained, proved by Elmendorf tear strength method. Also 61 % more flexibility of the tested plasticized PLA compound was achieved.
A reduction of more than 95 % of the water vapour permeability (WVTR) was obtained by adding 3.5 wt.-% of sepiolite S 80 (Tolsa) to plasticized PLA2003D.
Outer layer blend composition optimization.
A suitable way for optimal production of plasticized PLA compounds is the application of masterbatches. Following masterbatches were available during the compounding trials:
- Plasticizer: Lapol 108 loading 30 wt.-%
- Nucleating agent: Lapol HDT loading 20 wt.-%
- Sepiolite masterbatch: Sepiolite S 80 loading 15 wt.-%
WP4. Development of active PLA compounds for the inner layer
1.2.- Summary of progress towards objectives and details for each task;
WP4 aims to development PLA formulations suitable for the inner layer by compounding.
This layer will be the active system of the package where the antibacterial, antinfungal and antioxidant selected and encapsulated in WP2 must migrate from the package to the food at a specific rate for each selected fresh-cut food.
For this work package TECHNION examined the release kinetics of the selected active additives (PTSO). This was done following the achievement of the optimized sheet for the Inner layer by adjusting different processing parameters and blends composition of PLA and encapsulated Zeolite. The appropriate analytical technique for film's additives examination was assessed; calibration and optimization experiments for the extracting methods of the active compounds from the sheets were done. Finally, the release kinetics of PTSO from the film according to accelerated model for sheet storage was studied.
1.3.- Highlight clearly significant results;
It has been obtained some masterbatches with the encapsulated particles developed in WP2.
The formulation developed included PLA with 20%OLA and 20% of the active additive capsules. This masterbatches will be diluted in the extrusion process to obtain the suitable concentration.
Some aggregates have been observed, so to avoid the aggregates and to improve the dispersion and of the capsules without degradation, it is optimising the production, shear, and temperature with a starch capsules without any active additive.
With these masterbatches obtained will be produce sheets by extrusion process as a feedback of the compounding process optimization.
When this starch capsules will be optimised, the process conditions will be used to produce all the masterbatches with the active additives selected: PTSO, Mustard and Clove.
Based on the results, the PTSO measurement in the different films was extrapolated. With all different process parameters consideration, the most appropriate PTSO concentration in the film was defined, it will maximize the shelf-life of the packed product.
WP5. Multilayer active packaging based on modified PLA compounds.
1.2.- Summary of progress towards objectives and details for each task;
The overall goal of this Work Package was the development of suitable multilayer manufacturing processes at pilot plant level for the production of active packaging using the PLA compounds developed in previous WPs that fulfill the requirements of end-users applications.
The proposed multilayer manufacturing processes studied and optimized for the new compounds were: co-extrusion cast-sheet + thermoforming (semi-rigid tray) and co-extrusion blown-film extrusion (flexible bag and lid).
1.3.- Significant results;
1. The processability of the materials developed was optimised to obtain the final package with active additive (PTSO). It was obtained a three layer structure: A-B-C, with thickness ratio: 1/2/1 by cast-sheet and blown-film extrusion.
2. The multilayer sheets adapted perfectly to the pilot plant thermoforming machine and copied all the details from the mould and the multilayer films are suitable to be used in VFFS machines.
3. The migration of the PTSO to the food products was demonstrated to be effective. While PTSO was stable in the capsules and films before packaging (Milestone 5), here we show that the active compound (up to 40%) is released to the food within 9 days in the presence of the vegetables. This is a major achievement for the project.
4. The PLA packages preserve the vegetables and improve the product quality. These results suggest that the PLA packages indeed may act to prolong the shelf life of leaves.
5. Related to the antimicrobial activity of the PLA package, we found a microbial reductive trend for all of the PLA packed vegetables; we can point towards the possibility of the PLA package which act to preserve the vegetables by a partial bacterial growth inhibition.
6. The benefits of the PLA package with the PTSO capsules was observed even in cases that only PLA lids were used.
7. Altogether the PLA package was proved to be functionalized with the PTSO by controlled migration rates and to improve the product properties (quality, shelf-life, hygienic).
8. The kinetic of the PTSO release without vegetables differs from the release with vegetables, and is also affected by the vegetable type.
9. In the case of the cherry tomatoes we observed the same reductive trend (not statistical significant) towards the PLA tray in comparison to the control APET trays, probably because the tomatoes were damaged by mold and not by oxidation and microbial growth. We conclude that the PLA has a different impact on the preserving of different types of vegetables/fruits.
10. The target mechanical properties required for the films and sheets were fulfilled using the materials developed in the project.
11. A huge improvement in the water vapor barrier properties of the samples manufactured was obtained when compared to the commercial PLA.
WP6. Biodegradability and Ecotoxicity Evaluation
1.2.- Summary of progress towards objectives and details for each task;
The objective of this WP was the determination of biodegradation rate and the evaluation of the ecotoxicity of the multilayer active package obtained in WP5.
1.3.- Significant results;
Results obtained from the biodegradability and compostability test show:
• Both test samples (multilayer tray and lid) are fully biodegraded under controlled composting conditions by the end of the test period (180-d).
• Both test samples (multilayer tray and lid) contain >50% of volatile solids.
• The concentration of regulated heavy metals and other toxic substances in the test samples (tray and lid) are below than values given in standards EN 13432 and ISO 17088.
• Both test samples (multilayer tray and lid) show satisfactory disintegration, after 57-d in a controlled composting test, no material remained after sieving through a 2.0 mm sieve.
• The germination rate and plant biomass for the resulting composts (PLA + 15% S-80 and PLA + 30% LAPOL composts) are >90% of those in the corresponding blank compost.
According to the EN13432 an ISO 17088, it can be concluded that both test samples (multilayer tray and lid) are compostable.
WP 7. Industrial scale up and Product Validation
1.2.- Summary of progress towards objectives and details for each task;
Biopolymer compounds manufactured at pilot plant level was scaled up to industrial level by ADDCOMP.
Also, the development of suitable multilayer active packaging using the PLA compounds developed in ADDCOMP, at industrial level in ALESCO and POLYRAZ facilities.
In this WP it was studied the mechanical, thermal, barrier and migration properties, and also, there was performed the shelf life studies.
1.3.- Highlight clearly significant results;
The formulations developed in the project were obtained at industrial level in ADDCOMP facilities. These compounds obtained industrially were processed at industrial level in ALESCO and POLYRAZ facilities.
The film and sheets obtained industrially maintained the mechanical, thermal, and barrier properties comparing with the film developed in pilot plant, and also fulfil the overall migration standards.
There was obtained several packages, rigid and flexible. They were used by DOMCA and STRAUSS to introduce the fresh food inside. Then, the shelf life properties were studied fulfilling the results obtained at pilot plant level.
WP8. Environmental, Economic, Safety and Regulatory studies
1.2.- Summary of progress towards objectives and details for each task;
The main objective is to study the environmental sustainability (LCA), the recyclability and the end of life management. Also, it was asses in the economic viability of the new package and to ensure that the new packages fulfill legal requirements
1.3.- Significant results;
It was performed the LCA of the new PLA package compared to a PP package.
The PLA has lower global warming impact compared to the PP, but as the additives used (the active additive, the plasticiser…) are very new materials in the market, they are not fully optimized, and also there were purchased to USA companies, the impacts regarding production and transport increase the global warming of the package generated.
This impact will decrease using more optimized materials from Europe companies. In this situation, the cost of the material also will be reduced.
The package developed is fully recyclable, and fulfill the legal requirements.
WP9. Dissemination, exploitation and training.
1.2.- Summary of progress towards objectives and details for each task;
Plan for the use and dissemination of the foreground (M1-30). Two deliverables were produced along this task duration, D9.2 draft version submitted at the end of Period 1 M12 and 9.3 Final version of the PUDF M30. Both included the conditions for access to the Background.
Dissemination of the results. Theoretically the task started in M11, but several activities such as the website development and some general awareness activities have been advanced in the project in order to address the work package objectives. As part of task 9.2 the website kept updated, a workshop has been organised along P2 to promote the project results and achievements and a booth was run during the HISPACK show in Barcelona in May 2012.
Exploitation of the results. Started in M22 and will continue after the end of the project, the basis for the project results have been established and agreed by all the Consortium partners.
Training. Starting in M1, it was organised a training event, taking advantage a general assembly meeting, the RTD performers train the SMES technical staff on their activities, as a result of this session several training materials have been prepared and are available as a best practice guideline.
1.3.- Significant results;
The Consortium have worked on the project results identified in P1, the partners have expressed their exploitation interest in the different Exploitation Board Meetings arranged. As a result of this discussion an Exploitation Agreement has been signed by all the partners, main conclusion have been collected in the final version of the PUDF (D9.3).
The results and owners have been identified as follows:
Exploitable results / IPR Protection / Owner(s)
R1: Microencapsulation technology of active additives based on zeolites / Industrial Secret /
R2: PLA formulation for the outer layers based on OLA, organic/inorganic nucleants and water scavengers / Industrial Secret / 40% ADDCOMP + 30% ALESCO + 30% POLYRAZ
R3: PLA formulation for the inner layer based on OLA and active additives / Industrial Secret / 20%DOMCA + 30% ADDCOMP + 25% ALESCO + 25% POLYRAZ
R4: Multilayer active package for fresh-cut products with controlled release kinetics / Industrial Secret / 15%DOMCA + 35% ALESCO + 35% POLYRAZ + 15% TROYKA
R5: Packaging plant design for optimal use of the new package specifications / Industrial Secret / 100 % PROYMEC
The PUDF and the Exploitation agreement detailed the plans for using the SMEs results (Foreground) either through further development and commercial exploitation or through research including the conditions for the access to the Background.
The background used during the project implementation corresponding to RTD performers is available for the rest of the partners on a royalty free basis.
As part of Task 9.2 PLA4FOOD project was present in different events and conferences, a booth was run during the HISPACK show in Barcelona, RTD performers and SMEs `partners arranged different dissemination activities in different media accessible for them, press releases ad general public awareness campaigns have been organised, the project website used as a communication tool inside the Consortium kept updated and collected the main dissemination material and activities arranged.
A workshop about biodegradable multilayer package was hold in AIMMPLAS, and presented PLA4FOOD package as a success case study.
Several stakeholders have expressed their interest in the project contacting the general email: info through the project website, such as: Polymer (plastic transformer form Costa Rica), Plasticos Boulevares (Bolivia), Roger de Lauria (Cooking Training school), PhD students, etc. They have been invited and some of them attended the workshop organised in AIMPLAS to disseminate the project results.
The training material was collected in a two versions document D9.4 Best practice Guidelines, the public version gathered all the material about general processes carried out in the project, specific information about the PLA4FOOD project was included in the confidential version. The training event was arranged as part of a General Assembly meeting in Frankfurt, several material has been exchanged with the SME partners via email or conference calls in order to assist them during the scaling-up phase.
WP10. Management
After Period 1 the person in charge of the project - Mr Nuri Akkas - left the company due to healthy issues. From that date, he was replaced by Mr Ahmet Sumer, who had been lightly involved in PLA4FOOD activities during P1. Mr Sumer, became therefore responsible for technical and managerial issues related to PLA4FOOD. Since this change of responsible in TROYKA, communication became difficult with this Partner, and the problem has been increasingly worse. Lately he is not replying to emails, phone calls, neither signing letters to approve RTDs work and not attending any meeting.
The Consortium declare partner TROYKA defaulting party and the Coordinator send them a letter on behalf of the consortium asking for their costs statement or transferring the not approved funds to the project bank account.
All this impacted the Project activities because TROYKA, as end user of PLA4FOOD packages, should validate the fruit package developed in the project. Finally, an amendment was submitted to the EC, terminating TROYKA participation on the 1st December 2011 and internally redistributing TROYKA old tasks, most of them have been assumed by DOMCA.
Apart from the issue with partner TROYKA a fluent communication among the partners and the REA has been maintained during this period.
The scaling up process (WP7) has been several months delay due to the temporary lack of materials in the suppliers store, for this reason the acquisition time was longer than expected, additionally both technicians responsible for the project in ALESCO and POLYRAZ, the two SMEs involved in the scaling-up, have left respectively the companies, when shipment to or from Israel were arranged took more than expect due to customs service delays.
Deliverables due on this period were submitted on due time according to the annex I version 27/05/2013, as it is summarized in Table XIV.
Problems which have occurred and how they were solved or envisaged solutions;
RTD performer TECHNION asked for a budget transfer of 3.000 € from DEMO to RTD, this shift has been already approved by all the SMEs and reflected in WP 7. The subcontracting requested and allocation in the invoices from RTD to SME will remain unchanged as expected and detailed in the Annex I.
Changes in the consortium, if any;
TROYKA was declared defaulting party and a letter was sent to them asking for their costs statement, unfortunately no feedback was received, an amendment was consequently submitted to the EC, informing about this change in the Consortium.
List of project meetings, dates and venues;
Table XIII collects information about the meetings arranged during the 18 months of this reported period (01/12/2011-31/05/2013)
Date 11/01/2012 Purpose: Technical meeting – review of actions to face the scale up Location: TECHNION, Israel Participants: STRAUSS and TECHNION
Date 09/05/2012 Purpose: 18th month meeting Location: ICT, Germany Participants: All partners except: POLYRAZ, PROYMEC and TROYKA
Date 28-29/11/2012 Purpose: GA meeting Location: Frankfurt, Germany Participants: All partners except: POLYRAZ, PROYMEC, STRAUSS and TROYKA
Date 08/03/2013 Purpose: Technical meeting Location: AIMPLAS, Spain Participants: AIMPLAS, DOMCA, ADDCOMP, TECHNION and FRAUNHOFER
Further conference calls have been arranged between the partners in the Consortium to discuss technical and managerial issues, such as, the ones hold on the dates 03/02/2012; 05/03/2012, 26/03/2012, 13/04/2012, 24/04/2012, 29/05/2012, 10/07/2012, 11/10/2012, 07/11/2012, 11/01/2013, 30/01/2013, 04/02/2013, and 13/05/2013.
The minutes, presentations and further details about the meetings are available in the project website: http://www.aimplas.es/proyectos/pla4food/
Project planning and status;
Due to the delays caused by the raw materials stock, customs services and changes of the responsible technicians, WP7 was developed with approximately one month of delay according to the foreseen timing from Annex I.
Impact of possible deviations from the planned milestones and deliverables, if any;
All deliverables were submitted in some cases with deviations comparing to the timing, but reflecting the good results achieved in the project and the excellent package properties.
Any changes to the legal status of any of the beneficiaries, in particular non-profit public bodies, secondary and higher education establishments, research organisations and SMEs;
Not applicable
Development of the Project website, if applicable;
Further information about this topic can be found in the WP 9 ‘Dissemination, exploitation and training’. The project web site: http://www.aimplas.es/proyectos/pla4food/ is working properly since the early stages of the project. The contents on the private section have been increasing in relation to the project development.
Use of foreground and dissemination activities during this period (if applicable).
The final version of this document has been submitted to the REA together with the PPR in P2. The document aforementioned includes also the complete list of the dissemination activities carried out since the starting date of the project.
Consortium
Except the communication matter with TROYKA during the last P2, a fluent communication among the partners has been maintained during this period and also a good response when arranging meetings and with the meeting attendance has been received.
When some of the partners were not able to attend meeting different conference calls between the RTD performers and this partner took place after it.
A successful communication inside the Consortium has been shown when required, for example, declaration of TROYKA as defaulting party, approval of dissemination material (poster, project presentation, articles, etc), website comments; approval of budget shift of RTD performer.
REA
A fluent communication has been maintained with the REA highlighting the following issues:
- Assistance with the P1 Periodic Project Report submission and Form Cs delivery
- Approval of P1 reports and intermediate transfer
- Assistance with the cost category related to RTD performer: TECHNION
- Advices when communicating about the delays in the project
- New Project Officer has been assigned
- Amendment and procedure to follow with partner TROYKA termination
Potential Impact:
Fresh-cut fruits and vegetables exemplify the consumer driven products that have evolved from commodities to cater to European consumers’ increasing demand for healthy and easy-to-prepare foods. For vegetable and fruit producers/shippers, fresh-cut products have become a way to add value to their commodity products.
The demand for healthy and convenient products and advances in packaging technology has driven the expansion of the fresh-cut industry.
Gradually, the supermarket selection has expanded from just a bag of lettuce to mixed vegetables, complete salads and complete ready-to-eat meal components.
Growth in the consumption of fresh-cut products is expected to continue by close to 10% per year. The drivers for the increase in consumption of fresh-cut products in Europe are the rise in income levels, the increase in health consciousness, and the demand for convenience.
With extra discretionary income, consumers will spend more on quality and convenience food products. In general, produce consumption is also expected to increase due to growing awareness of the correlation between diet and health, and of the nutritional benefits of fruits and vegetables.
The emerging fresh-cut fruit sector will likely overshadow salad sales in the future because fresh-cut fruits are more attractive to young consumers and aging baby boomers and in general are more likely to be consumed as snack products.
Packaging has achieved ubiquitous presence on people’s daily life as confirmed in several market and economic reports providing indicators that reflect a constant growth during the last years, predicting as well a 6-10% yearly growth of packaging demand for the coming years. Particularly, food packaging has the highest percentage of consumption, representing the 52% of the world packaging market share with a market volume of 47 billion Euros in Europe . Food packaging has grown a 4% during 2008 being plastics the most consumed material for food packaging manufacture due to the wide range of possible combinations of polymers, additives and transformation processes, which makes them the most versatile material referring to shapes, costs and final properties of the package.
Plastic food packaging continues to be dominated by flexible formats (more than 65% of total plastic packaging sector) used for confectionery, bakery, savoury snacks and ice cream products . The most dynamic category among flexible packaging is pouches – used increasingly for sauces and other retorted foods due to their convenient format. The plastic flexible packaging market invoicing 20 billion Euros in Europe and generate around 100.000 employments. This sector is composed by around 7.000 companies, 85% of SMEs
Relevance to other industrial sectors.
• According to European Bioplastics, the total capacity of bioplastics (compostable and non compostable) by the end of 2011 was more than 1100 kt. That represents almost 5 time more compared 2009. The expected forecast in 2016 will be close to 5800 kt.
• The global polylactic acid (PLA) market is expected to grow at an annual compounded rate of 28% for the period 2011-2026, reaching USD 2.6bn. Europe follows at a CAGR of 28.9%, with the Americas expected to achieve 27.3%. According to Germany’s nova-Institut , the global PLA capacity could exceed 800,000 t/y by 2020 .
• Farmers obtaining a direct profit from this project. This can open new sales ways to their products in high added value markets. The possibilities to enlarge the shelf life of fresh cut products will lead to production delocalization to reach far away customers and in consequence to increase the competitiveness of their products. Additionally, natural additives are obtained for agricultural waste or aromatic plants, PLA4FOOD will help to valorize them.
The estimated time-to-market is up to two years after the end of the project, ensuring the quick commercialization of the project results and potential products.
The project results have been summarized in the list below:
Exploitable results / IPR Protection / Owner(s)
R1: Microencapsulation technology of active additives based on zeolites / Industrial Secret / 70% DOMCA + 30% ADDCOMP
R2: PLA formulation for the outer layers based on OLA, organic/inorganic nucleants and water scavengers / Industrial Secret / 40% ADDCOMP + 30% ALESCO + 30% POLYRAZ
R3: PLA formulation for the inner layer based on OLA and active additives / Industrial Secret / 20%DOMCA + 30% ADDCOMP + 25% ALESCO + 25% POLYRAZ
R4: Multilayer active package for fresh-cut products with controlled release kinetics / Industrial Secret / 15%DOMCA + 35% ALESCO + 35% POLYRAZ + 15% TROYKA
R5: Packaging plant design for optimal use of the new package specifications / Industrial Secret / 100 % PROYMEC
List of Websites:
http://www.aimplas.es/proyectos/pla4food
Contact
AIMPLAS - Instituto Tecnológico del Plástico
C/ Gustave Eiffel, 4 (València Parc Tecnològic) | 46980 - PATERNA (Valencia) – SPAIN
(+34) 96 136 60 40
info.pla4food@aimplas.es
PLA4FOOD proposal dealt with the development of innovative active and biodegradable packaging for fresh-cut food products based on renewable resources thermoplastic materials (PLA-polylactic acid) functionalised with the synergic addition of additives from natural sources (antioxidants, antibacterial and antifungal) in order to increase the shelf-life of packed products.
Different encapsulation routes were tested to protect active additives from processing conditions and to have controlled migration rates. Additionally, to minimize PLA current limitations in flexibility, water barrier properties and processability different additives were studied including bio-based lactic-acid plasticizers, inorganic nanofillers and organic nucleants.
The main application for these new active packages is the fresh-cut products packaging, specifically prepared and washed fruits and vegetables packaged without additives or preservatives in the food itself. These additives are currently added with the aim of achieving a minimum time of preservation of 7 days.
To develop this innovative active and biodegradable packaging to increase the shelf life of fresh-cut food products, several activities were carried out, focused in the following work areas:
- Studying the antimicrobial, antifungal and antioxidant effectiveness of natural selected active additives in several fresh cut products.
- Studying of different encapsulation technologies in order to protect active additives from processing conditions and allowing controlling their migration speed.
- Minimization of the current PLA limitations related to flexibility, barrier properties and processability.
- Obtaining of multi-layer structures from different PLA formulations, by means of diverse co-extrusion techniques (blown-film and cast-sheet and thermoforming) with the aim of getting the best cost/benefit ratio, and the optimum development of the active package through each layer’s thickness and crystallinity.
Project Context and Objectives:
Co-extrusion techniques (blow-film and cast-sheet and thermoforming) were developed to obtain multilayer structures from different PLA formulations, in order to achieve the best cost/benefit ratio and optimal performance of the active packaging by controlling the thickness and crystallinity of each layer.
First, it was defined the requirements for the active packaging to be developed for three specific fresh-cut products: salads, green vegetables and fruits. It has been defined and also the materials, additives and packaging process for each case study. The materials selected for the new package manufacture are at least a 95% from renewable resources.
It is studying the effectiveness of natural selected active additives in the three selected fresh – cut products and designing and optimizing encapsulation technology for antimicrobials, antifungals and antioxidants for the manufacturing of PLA based active packaging. Three additives were selected due to their antimicrobial, antifungal and antioxidant activity.
To optimize the outer layer, it is working in the improvement of PLA flexibility using different oligomeric lactic acid plasticizers (OLA). It was selected the most suitable one and the better concentration to obtain the flexible and rigid packages.
Water vapor permeability of the material was improved by the incorporation of scavenger to control the humidity into the package. It was selected the most promising filler and the better concentration. Currently it is optimizing the equipment and the process parameters.
The inner layer of the package will be the active system of the package where the antibacterial, antinfungal and antioxidant selected must migrate from the package to the food at a specific rate for each selected fresh-cut food.
To develop this inner layer it is currently developing the different blends of PLA with the encapsulated active additives by compounding process.
To develop the whole project, several processes were optimised:
Capsule formulation and production
During the project, several types of additives were employed. Garlic molecule was selected as an active additive encapsulated in inorganic and porous filler to protect it against the compounding process conditions (temperature and shear); sepiolites to improve the water vapour permeability of the package, and plasticisers to obtain better mechanical properties and to improve the material processability.
Based on the data obtained in the first period of the project, optimization of the capsule was done by means of re-formulation, in order to achieve the optimal methodology for the microcapsules processing.
The garlic which accommodates the inorganic fillers microcapsules is equivalent to 7% of the microcapsules total weight. From this garlic molecule load, it was lost 30% in the inorganic filler capsules during the first 14 days at 25°C. At 4°C we lost 30% in the inorganic filler capsules.
Considering these results and different parameters of optimization of the capsule formulation it was optimised protocols for microcapsules production and storage. These protocols allowed the incorporation of the required amounts of the active compounds in small capsules, and defined the conditions for slow release in order to keep the compounds in the capsules until they are added to the films.
Compounding process
According to the case studies selected and the Annex I, two different grades of PLA were used along the project. One PLA grade used for cast sheet extrusion and another PLA grade suitable for blown film extrusion applications. Since the crystallinity and behaviour of the two PLAs were different, several plasticizers were proved to check the efficient to improve PLA properties.
Two PLA grades from the company NatureWorks (USA) were selected. The tested new plasticizer for this work package was an oligomer lactic acid type, to increase the compatibility with PLA. A commercial grade of Lapol company from USA was used.
To achieve an optimal dispersion of the new plasticizers in the PLA matrix by extrusion, a suitable screw configuration designed for the optimal masterbatch production was used.
To avoid hydrolytic degradation of the biopolymer PLA and the biobased additives a venting system was used to remove water during compounding. The venting system consists of an atmospheric and a vacuum degassing unit.
The processing of plasticised is limited due to the sensitive of the resin to heat and thermal treatment. Re-melting plasticiser resin more than three times may result in gelling and compromise properties.
Multilayer blown film and cast sheet manufacturing
The objective was to optimize the processes parameters to obtain a multilayer structure without interfacial instabilities and encapsulation problems.
The following aspects of each multilayer configuration has been controlled and optimized:
• To optimize processing temperatures’ profiles of each extruder.
• Speed of extrusion in each extruder. This parameter offers us the adequate residence time that will allow the material to flow with the right viscosity.
• The thickness of each layer obtained according to the material’s properties and extruders output to avoid problems of flow and/or interface instabilities.
The thermal, mechanical resistance, thickness distribution and homogeneity was used as control parameters.
It was optimised the multilayer structure by reducing the thickness in the functional layers (with water scavengers and inorganic fillers) in order to minimize the cost.
The ratio between the layers was adjusted to avoid interfacial defects, and the total thickness was the suitable to be thermoformed according to the depth of the tray selected to pack the food in the industrial scale-up, and to obtain a tray with good mechanical properties.
Packaging process
The sheets obtained were thermoformed to obtain the rigid package (trays) and the films developed were used to obtain the flexible packages (bags) and to close the trays.
The films and sheets obtained in the project showed good properties and they fulfil the requirements established. The new developed packages showed high flexibility and good barrier properties compared with the commercial grades by the effect of the additives added.
The packages developed are suitable to be in contact with fresh cut food according to the overall migration analysis performed and they are fully compostable.
Project Results:
As a result from the combination of advances material science and improvements in processing technologies, an active and biodegradable package from renewable sources it is being developed. This packaging has applications in the food industry, and provides products with protection against environmental agents, improvements in the preservation of the packaged product’s properties (quality, shelf life, microbiological safety, and nutritional values), but also being biodegradable under compostability conditions, according to the UNE-EN 13432 European standard.
The main achievements fulfilled with the PLA4FOOD project development are summarized below:
1. The processability of the materials developed was optimised to obtain the final package with active additive-garlic. It was obtained a three layer structure by cast-sheet and blown-film extrusion.
2. The multilayer sheets adapted perfectly to the pilot plant thermoforming machine and copied all the details from the mould and the multilayer films are suitable to be used in VFFS machines.
3. The migration of the garlic to the food products was demonstrated to be effective. While garlic molecule was stable in the capsules and films before packaging it was showed that the active compound (up to 40%) is released to the food within 9 days in the presence of the vegetables.
4. The PLA packages preserve the vegetables and improve the product quality. These results suggest that the PLA packages indeed may act to prolong the shelf life of the different types of leaves.
5. Related to the antimicrobial activity of the PLA package, it was found a microbial reductive trend for all of the PLA packed vegetables; it can be pointed towards the possibility of the PLA package which act to preserve the vegetables by a partial bacterial growth inhibition.
6. The benefits of the PLA package with the garlic capsules was observed even in cases that only PLA lids were used.
7. Altogether the PLA package was proved to be functionalized with the garlic by controlled migration rates and to improve the product properties (quality, shelf-life, hygienic).
8. The kinetic of the garlic release without vegetables differs from the release with vegetables, and is also affected by the vegetable type.
9. The target mechanical properties required for the films and sheets were fulfilled using the materials developed in the project.
10. An improvement in the water vapor barrier properties of the samples manufactured was obtained when compared to the commercial PLA.
Next it is showing the results highlighted from each WP.
WP 1. Definition of requirements, case studies and selection of additives and materials
1.2.- Summary of progress towards objectives and details for each task;
The WP1 main objective was the definition of the requirements for the active packaging to be developed for three specific fresh-cut products.
The three typologies of products: salads, green vegetables and fruits have been defined and also the materials, additives and packaging process for each case study.
The materials selected for the new package manufacture has more than 95% from renewable resources.
1.3.- Highlight clearly significant results;
Case studies selected are summarized in table 1.
Table 1 Case study selected
1 Salad – Iceberg lettuce Package: Flexible Film/sheet producer: ALESCO Package producer: STRAUSS Active additive:Antibacterial
2 Salad – Romaine lettuce Package: Rigid Film/sheet producer: POLYRAZ-tray
ALESCO-lid Package producer: STRAUSS Active additive: Antibacterial
3 Green vegetable – Beet leaves Package: Flexible Film/sheet producer: ALESCO Package producer: STRAUSS, Active additive: Antibacterial and antioxidants
4 Fruit – tomato Package: Rigid Film/sheet producer: POLYRAZ-tray
ALESCO-lid Package producer: TROYKA Active additive: Antifungal and antioxidants
The different requirements of the new package have been defined:
• The co-extrusion (film and sheet) and thermoforming process parameters: industrial equipment available in the partners companies, dimensions of the film and sheet, melt temperatures, output and residence time between others.
• Finishing packaging process needed: thermoforming and packaging process regarding equipment, mould and film dimensions, sealing conditions,...
• Other issues regarding filling process, transport and conservation conditions.
• Recycling process in order to study the re-processability of industrial scrap or post-consume packages o establish if the recycled material may be incorporated with influencing in loss of new product properties.
Selection of natural antimicrobials, antifungal and antioxidant additives.
The most suitable additives according to the selected food and the process parameters were selected.
Selection of PLA grades and flexural PLA modifiers.
From the PLA grades review, the most suitable for the project development are supplied by NATURE WORKS. It were selected two different grades, one for rigid packaging applications and another for flexible packages.
Further additionally additives were necessary in order to improve the PLA processability and properties:
o Plasticizers. The most compatible with PLA is OLAs to minimize the migration and to improve the miscibility.
o Water scavengers. The most suitable are sepiolites. It was selected a sepiolite with the proper surface modification to increase the PLA compatibility.
o Organic nucleants. It was selected several nucleants from different suppliers, with another function, as an impact modifiers or melt strength enhancer to improve the material properties.
WP2. In vitro study of additives effectiveness over the food. Microencapsulation of selected additives.
1.2.- Summary of progress towards objectives and details for each task;
The goal of WP2 was to study the effectiveness of natural selected active additives in the three selected fresh – cut products and design and optimize encapsulation technology for antimicrobials, antifungals and antioxidants for the manufacturing of PLA based active packaging.
Study of the “in vitro” activity of the selected antimicrobials, antifungal and antioxidants.
An initial experiment was conducted to evaluate the microorganism populations on these fresh vegetables and a comparison was made with EC and Israeli regulations. Cut Iceberg leaves and beet leaves were found to contain high levels of coliforms. 108 samples of beet leaves were evaluated with a mean value of 280,000 cfu/gr, and 40% of samples contained coliforms above 100,000 cfu/gr. The coliform counts increase significantly around the mid-period of shelf-life (after day 6).
The active antimicrobial additives selected by DOMCA were: Propyl Propene Thiosulfonate (PTSO), Synthetic mustard oil (Allyl isothiocyanate), Tetraene polyene macrolide (Natamycin) ,and Bacteriocin DMC, Eugenol. Antimicrobial activity of all 5 compounds was assessed ‘in vitro’ against microorganisms that were purified from each product (at least 6 microorganisms from each product). Compounds PTSO, Synthetic mustard oil and Eugenol showed high activity against standard (ATCC strains) and against a wide variety of microorganisms (mezophilic-aerobic, coliforms, lactic acid bacteria, yeast/mold) we had isolated from the food products. Eugenol was active against all microorganisms with MIC bellow 0.1 g/L, and the other compounds had MICs of 0.16 or less. Compounds 3 (Natamycin) and 4 (DMC bacteriocin) showed little or no activity against all types of bacteria tested.
The activity of the antimicrobial additives PTSO, Mustard oil and Eugenol against microorganisms on the products was investigated by dipping the product in water solutions containing different concentrations of the active compounds. These experiments were done using Beet leaves, Iceberg lettuce and Cherry tomatoes. All compounds used were efficient against the different groups of microorganisms on the different products. Washing with the lower concentrations were less effective, but usually resulted in at least 2-log reduction. In low concentrations (0.1%) PTSO showed the most efficient antibacterial activity against coliforms in all the vegetable, with the most significant reduction exhibited in beet leaves. In high concentrations (1% and above) PTSO and Mustard oil exhibited high antimicrobial potential. All three active compounds were effective against coliforms on cut Iceberg leaves and on tomatoes. Eugenol showed high antibacterial activity on tomatoes as well. When high concentrations were used significant color changes were seen on the cut lettuce leaves, while the lower concentration (0.1%) did not alter the leaves color. All compounds showed an efficient antifungal activity in tomatoes.
In order to assess the activity of the additives: PTSO, Mustard oil and Eugenol, a shelf life experiment was conducted on the selected fresh cut products. The antimicrobials were diluted to different concentrations and spread on the inner parts of the current (PE and PP) package sheets. Microbial counts were measured during shelf life. Results of the microbial counts showed that PTSO had an efficient antibacterial activity against all microorganisms. However, the shelf-life was not increased. The compound significantly damaged the leaves which a distinct color and structure change, loss of water and had become soft.
When cut leaves of Iceberg lettuce were examined for the antimicrobial activity of the additives it was seen that at high concentrations of Mustered oil had a high antimicrobial activity, particularly against coliforms, followed by Eugenol, which usually had better activity against lactic acid bacteria. All compounds had good activity against yeasts, which exists in very low levels on the selected products. In lower concentrations (≤1%) the antimicrobials were not significantly effective, but in some cases still damaged the leaves before the end of the products shelf-life. In order to understand if the continues exposure to the antimicrobial has impact on the products damage during shelf life, an additional shelf life experiment was conducted with the selected food products. In this experiment the vegetables were pre-washed in a solution containing the antimicrobial additives. Pre-washing of beet leaves with all active compounds (1%) had resulted with very low microbial counts at the end of the products shelf-life. The lower concentrations of the active additives (0.1%) did not show significant antimicrobial effect and the bacterial counts results were similar to the controls. Nevertheless, pre-washing with all active additives (0.1-1%) had resulted with spoilage of the product before end of shelf-life. Similar results were observed when cut Iceberg lettuce samples were pre-washed with PTSO (1%) and Mustard oil (1%). The tomatoes shelf life results showed that 1% of Mustard oil had reduced the bacteria dramatically while the changes in tomatoes appearance were negligible.
In order to study the effect of the additive compounds in very low concentrations a new shelf life experiment was conducted. The concentrations used in this experiment were too low for antimicrobial activity, but still enabled to maintain some antioxidant activity and probably other activities (such as inhibition of enzymatic activity) that may impact the products quality.
The definition of the shelf life of these fresh cut products is: ‘the product will be disqualified for marketing if more that 20% of the leaves are spoiled or oxidized‘(Strauss). All leaves that had shown a color change were considered to be oxidized and were disqualified for marketing. After administering the active materials to the food products fewer packages were disqualified as compared to untreated packages. When using PTSO only 17 packages were disqualified as compared to 42 without the treatment. Mustard oil had improved shelf life for 20% more packages as compared to the control. It can be concluded that PTSO and Mustard oil in low concentration of 0.001 and 0.0001 (gr/Package of 100 gr leaves), respectively, had been able to increase shelf-life of leaves, probably by antioxidant activity.
From the study of 5 natural active additives, provided by DOMCA, it was concluded that PTSO (garlic), Synthetic mustard oil and Eugenol (clover) showed a broad range of activities against gram positive and gram negative bacteria presented in the food products, including coliforms and E. coli, and against eukaryotes (yeast, mold) as well. Moreover, PTSO and Eugenol also have antioxidant activity. Since the activity of the additives changes in the different products (cut lettuce leaves, beet leaves and cherry tomatoes), the two most suitable additives for each of the food products were defined. PTSO and mustard oil usually had the best activity. For that reason work was focused on production of microcapsules with both additives. However, some preliminary experiments were also conducted with Eugenol. The approximate range of optimal concentrations of each type of additive for each type of food that expected to maximize the shelf-life of the packed product was also determined. This was based on the fact that the antimicrobial compounds were found to be very active in solution but have only limited antimicrobial activity when they were spread on the packaging sheets, and in high concentrations it was paralleled with a significant decrease in the quality of the products.
Study and development of microcapsules.
The aim of this step was to create the starch-active additive (PTSO, Mustard oil and Eugenol) microcapsules in a pilot scale with a continuous process that will be suitable for scale up for the industry, as well as for the preparation of large samples for product formulations, testing, and in-vivo experiments. In order to form sub micron capsules, the process has been performed using dual feed jet homogenizer.
Zeolite is a hydrophobic crystalline aluminosilicate with a network of channels and cavities with pore diameters in the range of 0.7-1.2 nm. It has a high thermal, mechanical and chemical stability that can be transferred to the encapsulation additive. The production of Zeolite-active additive (PTSO, Mustard oil and Eugenol) microcapsules was carried out in bench-top scale but can easily be converted to a continuous industrial process.
Thermal stable microcapsules containing active additives were developed and design and defined the microcapsule coatings, process of development and load. Zeolite and starch based microcapsules were developed.
Characterization of the capsules.
Light microscopy and SEM images were obtained in order to gain information on the aggregates size and morphology. All HACS microcapsules aggregates have a large population of very small particles (less than 5 µm) and bigger aggregates.
From the SEM images it is evident that there are morphological differences between the three microcapsules. Their shapes are not uniformed, amorphous and highly porousive. HACS-PTSO and HACS-Eugenol have similar pours or cavities shapes as compared to HACS-Mustered oil which have smaller pours but are more clustered.
Particle size analysis was performed by laser diffraction sizing of particles. A typical size analysis for HACS microcapsules samples showed a collection of aggregated sub-particles. The volume weighted mean average of the particles was ~ 8 µm and surface weighted mean average was ~6 µm. The industrial PLA packaging process requires an average particle size of ~ 5 µm. These microcapsules reversible aggregates contain single particles in the sub-micron size level that fit the size required criteria.
DSC was applied to test the thermal properties and dissociation temperatures of starch-active additive complexes. A DSC analysis was conducted to simulate the PLA packaging process. In this analysis we had attempted to simulate the temperature profile of the extruder processes used for the compounding of the PLA, film production and thermoforming of the PLA trays. From the results obtained for HACS –active material microcapsules, it is apparent that no significant thermal event has occurred during all 3 heating stages. The starch based microcapsules showed thermal stability throughout the analysis with no indication of any thermal event or melting event.
The objective of this task was to incorporate the maximum amount of bioactive ingredient in the capsules. In order to find the best encapsulation formulation three active materials (PTSO, Mustard oil and Eugenol) were encapsulated in starch (HACS) and Zeolite and a the microcapsules contents were established. HACS microcapsules showed a higher load content when PTSO was encapsulated as compared to the Zeolite microcapsules. Similar content results in both microcapsules were obtained when Mustard oil and Eugenol were encapsulated, ~2% and ~6%, respectively.
Capsule size was evaluated by microscopy or particle size analyzers. Morphology was studied by SEM. Thermal stability was evaluated to simulate processing conditions. The kinetics of the release of the bioactive was evaluated by following the bioactive content in the capsules along simulate storage conditions.
Based on the data obtained in the first part of the WP, optimization of the capsule by means of re-formulation was done, in order to achieve the optimal methodology for the microcapsules processing.
1.3.- Highlight clearly significant results;
The goal was to study the effectiveness of natural selected active additives in the three fresh-cut products and design and optimize encapsulation technology. During the first 9 months, Microbial tests with the 5 antimicrobial compounds obtained from DOMCA have been conducted by TECHNION in order to determine the best compound properties, additionally it has been found that the three compounds had an excellent antimicrobial activity in vitro and in vivo, unfortunately the compounds also hurt the fresh-cut products, and thus did not increase the shelf life in the range of concentrations that gave the optimized antimicrobial activity.
- The Beet leaves are the most sensitive product to microbial growth, and cut lettuce leaves are more sensitive than intact leaves.
- Antimicrobial activity of the selected additives should focus on coliform counts.
- Compounds: PTSO, Mustard oil and Eugenol showed more efficient antibacterial activity as compared to Natamycinand and DMC bacteriocin which showed little or no activity against all types of bacteria tested.
- In some shelf life tests the antibacterial activity was paralleled with a significant decrease in the quality of the products.
- The results showed that mold and yeast were not a significant problem in the 4 selected food products.
- Based on the results of the experiments described above the following additives are suggested for each of the food products:
• Cut Iceberg leaves: PTSO, Mustard oil
• Beet leaves: PTSO, Mustard oil, Eugenol
• Tomatoes: Mustard oil, PTSO
- Optimal concentrations of each type of additive for each type of food that maximizes the shelf-life of the packed product:
Cut Iceberg leaves: PTSO (~0.001 gr/package of 100 gr), Mustard oil (~0.0001 gr/package of 100 gr)
Beet leaves: PTSO (~0.001 gr/package of 100 gr), Mustard oil, Eugenol (~0.0001 gr/package of 100 gr)
Tomatoes: Mustard oil (~0.01 gr/package of 100 g), PTSO (~0.001 g)
Experiments conducted to achieve the goals of Task 2.1 have been completed.
1. Starch based and zeolite microcapsules were developed for the encapsulation of antimicrobial, antifungal and antioxidant active additives.
2. Starch based microcapsuled showed thermal stability in simulated PLA processing conditions.
3. Starch and Zeolite microcapsules fit the size criteria established for the PLA processing conditions.
4. Starch and Zeolite microcapsules have similar load contents when encapsulating Mustard oil and Eugenol.
5. Starch microcapsules showed better encapsulating ability when PTSO was loaded in the capsule compared to Zeolite.
Considering the different parameters of optimization of the capsule formulation, it was recommended on PTSO encapsulated in HACS (starch) or Zeolite X (CECA S.A) or Mustard Extract encapsulated in Zeolite X (CECA S.A).
WP3. Development of PLA compounds with improved performance for the outer layers
1.2.- Summary of progress towards objectives and details for each task;
Formulations of PLA with oligomer lactic acid plasticizers.
In order to improve the flexibility of PLA, different oligomeric lactic acid plasticizers (OLA) were prepared by using a strand pelletizing process consisting of a co-rotating twin-screw extruder with degassing units and side-feeder (for the feeding of plasticizers). The changes in flexibility by using the plasticizers from company Futerro (Belgium) are very small. Even at the highest amount of OLA plasticizer the E modulus was not influenced and the elongation was decreased. The suitable OLA plasticizer to improve the flexibility of PLA is OLA8 (Condensia, Spain) and Lapol 108 (Lapol, USA). The advantage of Lapol 108 plasticizer is the availability of a masterbatch, for better dosing and feeding. The effective dosage of Lapol 108 to obtain flexibility is lower compared to OLA 8 plasticzizer. The E modulus and the tensile strength were significantly decreased, the elongation increased. All plasticized PLA compounds show no reduction in transparency up to 20 wt.-% Lapol 108, they were miscible with the selected PLA grades PLA2003D and PLA4032D from NatureWorks (United States). The heat deflection temperatures (HDT) of all plasticized PLA compounds were lower than the HDT of pure PLA. The flow behaviour of plasticized PLA2003D and PLA4023 are very similar. The changes in the mechanical and thermal properties are also similar. The only difference between these compounds was the higher reduction in tensile strength and E modulus for the grade PLA2003D.
Development of plasticized PLA compounds with increased the thermal resistance by using organic/inorganic nucleants.
The effect of improving the mechanical properties of plasticized PLA by nucleation is not only depending on the amount of the nucleating agent. The main factors are the process conditions and the selected process. In the injection moulding process with higher tooling temperature (100 °C) and long residence time (180 s) of material in the mould enhanced mechanical and thermal properties were obtained. The plasticized PLA compound with nucleating agents was also more flexible. The tested nucleating agents were SUKANO PLA na S516 from Sukano AG (Switzerland) and CN-L01 Polyvel, Inc. (USA).
To transform these results from the injection moulding process to film manufacturing (blown film, cast film) and thermoforming process additional test will be carried out.
Development of PLA compounds for the outer layers.
a) Plasticized PLA and sepiolite
A suitable method to incorporate sepiolite clay in a plasticized PLA is to produce a sepiolite masterbatch (15 wt.-% sepiolite) and to dilute it to the required amount. Two batches of plasticized PLA with sepiolites grades S-20 and S-80 from company Tolsa (Spain) were provided to AIMPLAS for film and sheet manufacturing. The measurement of the water vapour permeability (WVTR) is still in process.
b) Plasticized PLA masterbatch
A masterbatch with a loading of 40 wt.-% OLA8 in PLA2003D was produced. After a drying process the granules were not sticky and show no transparency. This plasticized PLA masterbatch can be diluted easy to the required OLA plasticizer level for using in food packaging applications. This masterbatch will be diluted to adapt the OLA percentaje round 20 % showing an adequate transparency.
c) Design of experiment (DoE)
To conduct the DoE method different data and information were collected.
The effect of different additives on plasticized PLA were studied. The effect of the applied additives in plasticized PLA shows no significant changes in the tensile properties at the used additive level. The effect of specific mechanical energy (SME) on the properties of plasticized PLA was only significant for the OLA8 plasticizer. No changes in the mechanical properties were obtained by using the grade EP0005 at different SME values. For good dispersion of plasticizer in PLA a suitable OLA grade and high SME is required.
Production and characterization of the different monolayer films and sheets.
The compounds developed have been processed on a pilot plant monolayer extrusion line to produce sheets (extruder + die + cooling roll + calendar). With the rheological and mechanical data, the parameters for the extrusion to be optimized are the temperature profile, speed of extrusion, screw design and stretch ratio. Also, die design and roll temperature must be studied.
The use of masterbatch requires paying special attention in the selection of the screw extruder in order to reach a high level of dispersion of the additives embedded in a low viscosity PLA matrix. The produced films were characterized by a) thermal analysis, b) mechanical methods and c) permeability analysis.
1.3.- Highlight clearly significant results;
The suitable plasticizer to improve the flexibility of PLA is Lapol 108 (Lapol, USA). All plasticized PLA compounds show no reduction in transparency up to 20 wt.-% plasticizer.
Using nucleating agents leads to an improvement in (injection moulded parts):
- Heat deflection temperature (HDT) from 39 °C to 44 °C
- Notched impact strength from 1.6 kJ/m2 to 3.0 kJ/m2
a) The incorporation of sepiolites in plasticized PLA compound is possible via a masterbatch route.
b) A masterbatch with a loading of 40 wt.-% OLA8 in PLA2003D was produced.
c) The effect of additives, recommended for PLA applications, in plasticized PLA (9 wt.-% OLA8) shows no significant changes in the tensile properties at the used additive level.
Using the nucleating agent Lapol HDT leads to an improvement in (injection moulded parts, PLA4032D, 20 wt.-% Lapol HDT, 15 wt.-% Lapol 108):
- Heat deflection temperature (HDT B) from 52 °C to 64 °C
- Notched impact strength from 1.8 kJ/m2 to 3.7 kJ/m2
- Elongation from 2.6 % to 7 %
The measurement of the water vapour permeability (WVTR) will be performed with the optimised film sheet obtained.
The incorporation of sepiolite S 80 (Tolsa) in plasticized PLA compound is feasible via a masterbatch route. The optimal process conditions for good dispersion of sepiolites particles in PLA matrix is a high specific mechanical energy (SME) intake.
A masterbatch with a max. loading of 30 wt.-% Lapol 108 in PLA2003D and PLA4032D was produced. Four different PLA compounds are available for film or sheet production:
- PLA2003D with loading of 20 and 30 wt.-% Lapol 108
- PLA4032D with loading of 20 and 30 wt.-% Lapol 108
Production and characterization of the different monolayer films and sheets.
The glass transition temperature Tg of all plasticized PLA compounds were about 60 °C.
Improvement of 440 % in elongation of plasticized PLA (loading 18 wt.-% Lapol 108) was obtained, proved by Elmendorf tear strength method. Also 61 % more flexibility of the tested plasticized PLA compound was achieved.
A reduction of more than 95 % of the water vapour permeability (WVTR) was obtained by adding 3.5 wt.-% of sepiolite S 80 (Tolsa) to plasticized PLA2003D.
Outer layer blend composition optimization.
A suitable way for optimal production of plasticized PLA compounds is the application of masterbatches. Following masterbatches were available during the compounding trials:
- Plasticizer: Lapol 108 loading 30 wt.-%
- Nucleating agent: Lapol HDT loading 20 wt.-%
- Sepiolite masterbatch: Sepiolite S 80 loading 15 wt.-%
WP4. Development of active PLA compounds for the inner layer
1.2.- Summary of progress towards objectives and details for each task;
WP4 aims to development PLA formulations suitable for the inner layer by compounding.
This layer will be the active system of the package where the antibacterial, antinfungal and antioxidant selected and encapsulated in WP2 must migrate from the package to the food at a specific rate for each selected fresh-cut food.
For this work package TECHNION examined the release kinetics of the selected active additives (PTSO). This was done following the achievement of the optimized sheet for the Inner layer by adjusting different processing parameters and blends composition of PLA and encapsulated Zeolite. The appropriate analytical technique for film's additives examination was assessed; calibration and optimization experiments for the extracting methods of the active compounds from the sheets were done. Finally, the release kinetics of PTSO from the film according to accelerated model for sheet storage was studied.
1.3.- Highlight clearly significant results;
It has been obtained some masterbatches with the encapsulated particles developed in WP2.
The formulation developed included PLA with 20%OLA and 20% of the active additive capsules. This masterbatches will be diluted in the extrusion process to obtain the suitable concentration.
Some aggregates have been observed, so to avoid the aggregates and to improve the dispersion and of the capsules without degradation, it is optimising the production, shear, and temperature with a starch capsules without any active additive.
With these masterbatches obtained will be produce sheets by extrusion process as a feedback of the compounding process optimization.
When this starch capsules will be optimised, the process conditions will be used to produce all the masterbatches with the active additives selected: PTSO, Mustard and Clove.
Based on the results, the PTSO measurement in the different films was extrapolated. With all different process parameters consideration, the most appropriate PTSO concentration in the film was defined, it will maximize the shelf-life of the packed product.
WP5. Multilayer active packaging based on modified PLA compounds.
1.2.- Summary of progress towards objectives and details for each task;
The overall goal of this Work Package was the development of suitable multilayer manufacturing processes at pilot plant level for the production of active packaging using the PLA compounds developed in previous WPs that fulfill the requirements of end-users applications.
The proposed multilayer manufacturing processes studied and optimized for the new compounds were: co-extrusion cast-sheet + thermoforming (semi-rigid tray) and co-extrusion blown-film extrusion (flexible bag and lid).
1.3.- Significant results;
1. The processability of the materials developed was optimised to obtain the final package with active additive (PTSO). It was obtained a three layer structure: A-B-C, with thickness ratio: 1/2/1 by cast-sheet and blown-film extrusion.
2. The multilayer sheets adapted perfectly to the pilot plant thermoforming machine and copied all the details from the mould and the multilayer films are suitable to be used in VFFS machines.
3. The migration of the PTSO to the food products was demonstrated to be effective. While PTSO was stable in the capsules and films before packaging (Milestone 5), here we show that the active compound (up to 40%) is released to the food within 9 days in the presence of the vegetables. This is a major achievement for the project.
4. The PLA packages preserve the vegetables and improve the product quality. These results suggest that the PLA packages indeed may act to prolong the shelf life of leaves.
5. Related to the antimicrobial activity of the PLA package, we found a microbial reductive trend for all of the PLA packed vegetables; we can point towards the possibility of the PLA package which act to preserve the vegetables by a partial bacterial growth inhibition.
6. The benefits of the PLA package with the PTSO capsules was observed even in cases that only PLA lids were used.
7. Altogether the PLA package was proved to be functionalized with the PTSO by controlled migration rates and to improve the product properties (quality, shelf-life, hygienic).
8. The kinetic of the PTSO release without vegetables differs from the release with vegetables, and is also affected by the vegetable type.
9. In the case of the cherry tomatoes we observed the same reductive trend (not statistical significant) towards the PLA tray in comparison to the control APET trays, probably because the tomatoes were damaged by mold and not by oxidation and microbial growth. We conclude that the PLA has a different impact on the preserving of different types of vegetables/fruits.
10. The target mechanical properties required for the films and sheets were fulfilled using the materials developed in the project.
11. A huge improvement in the water vapor barrier properties of the samples manufactured was obtained when compared to the commercial PLA.
WP6. Biodegradability and Ecotoxicity Evaluation
1.2.- Summary of progress towards objectives and details for each task;
The objective of this WP was the determination of biodegradation rate and the evaluation of the ecotoxicity of the multilayer active package obtained in WP5.
1.3.- Significant results;
Results obtained from the biodegradability and compostability test show:
• Both test samples (multilayer tray and lid) are fully biodegraded under controlled composting conditions by the end of the test period (180-d).
• Both test samples (multilayer tray and lid) contain >50% of volatile solids.
• The concentration of regulated heavy metals and other toxic substances in the test samples (tray and lid) are below than values given in standards EN 13432 and ISO 17088.
• Both test samples (multilayer tray and lid) show satisfactory disintegration, after 57-d in a controlled composting test, no material remained after sieving through a 2.0 mm sieve.
• The germination rate and plant biomass for the resulting composts (PLA + 15% S-80 and PLA + 30% LAPOL composts) are >90% of those in the corresponding blank compost.
According to the EN13432 an ISO 17088, it can be concluded that both test samples (multilayer tray and lid) are compostable.
WP 7. Industrial scale up and Product Validation
1.2.- Summary of progress towards objectives and details for each task;
Biopolymer compounds manufactured at pilot plant level was scaled up to industrial level by ADDCOMP.
Also, the development of suitable multilayer active packaging using the PLA compounds developed in ADDCOMP, at industrial level in ALESCO and POLYRAZ facilities.
In this WP it was studied the mechanical, thermal, barrier and migration properties, and also, there was performed the shelf life studies.
1.3.- Highlight clearly significant results;
The formulations developed in the project were obtained at industrial level in ADDCOMP facilities. These compounds obtained industrially were processed at industrial level in ALESCO and POLYRAZ facilities.
The film and sheets obtained industrially maintained the mechanical, thermal, and barrier properties comparing with the film developed in pilot plant, and also fulfil the overall migration standards.
There was obtained several packages, rigid and flexible. They were used by DOMCA and STRAUSS to introduce the fresh food inside. Then, the shelf life properties were studied fulfilling the results obtained at pilot plant level.
WP8. Environmental, Economic, Safety and Regulatory studies
1.2.- Summary of progress towards objectives and details for each task;
The main objective is to study the environmental sustainability (LCA), the recyclability and the end of life management. Also, it was asses in the economic viability of the new package and to ensure that the new packages fulfill legal requirements
1.3.- Significant results;
It was performed the LCA of the new PLA package compared to a PP package.
The PLA has lower global warming impact compared to the PP, but as the additives used (the active additive, the plasticiser…) are very new materials in the market, they are not fully optimized, and also there were purchased to USA companies, the impacts regarding production and transport increase the global warming of the package generated.
This impact will decrease using more optimized materials from Europe companies. In this situation, the cost of the material also will be reduced.
The package developed is fully recyclable, and fulfill the legal requirements.
WP9. Dissemination, exploitation and training.
1.2.- Summary of progress towards objectives and details for each task;
Plan for the use and dissemination of the foreground (M1-30). Two deliverables were produced along this task duration, D9.2 draft version submitted at the end of Period 1 M12 and 9.3 Final version of the PUDF M30. Both included the conditions for access to the Background.
Dissemination of the results. Theoretically the task started in M11, but several activities such as the website development and some general awareness activities have been advanced in the project in order to address the work package objectives. As part of task 9.2 the website kept updated, a workshop has been organised along P2 to promote the project results and achievements and a booth was run during the HISPACK show in Barcelona in May 2012.
Exploitation of the results. Started in M22 and will continue after the end of the project, the basis for the project results have been established and agreed by all the Consortium partners.
Training. Starting in M1, it was organised a training event, taking advantage a general assembly meeting, the RTD performers train the SMES technical staff on their activities, as a result of this session several training materials have been prepared and are available as a best practice guideline.
1.3.- Significant results;
The Consortium have worked on the project results identified in P1, the partners have expressed their exploitation interest in the different Exploitation Board Meetings arranged. As a result of this discussion an Exploitation Agreement has been signed by all the partners, main conclusion have been collected in the final version of the PUDF (D9.3).
The results and owners have been identified as follows:
Exploitable results / IPR Protection / Owner(s)
R1: Microencapsulation technology of active additives based on zeolites / Industrial Secret /
R2: PLA formulation for the outer layers based on OLA, organic/inorganic nucleants and water scavengers / Industrial Secret / 40% ADDCOMP + 30% ALESCO + 30% POLYRAZ
R3: PLA formulation for the inner layer based on OLA and active additives / Industrial Secret / 20%DOMCA + 30% ADDCOMP + 25% ALESCO + 25% POLYRAZ
R4: Multilayer active package for fresh-cut products with controlled release kinetics / Industrial Secret / 15%DOMCA + 35% ALESCO + 35% POLYRAZ + 15% TROYKA
R5: Packaging plant design for optimal use of the new package specifications / Industrial Secret / 100 % PROYMEC
The PUDF and the Exploitation agreement detailed the plans for using the SMEs results (Foreground) either through further development and commercial exploitation or through research including the conditions for the access to the Background.
The background used during the project implementation corresponding to RTD performers is available for the rest of the partners on a royalty free basis.
As part of Task 9.2 PLA4FOOD project was present in different events and conferences, a booth was run during the HISPACK show in Barcelona, RTD performers and SMEs `partners arranged different dissemination activities in different media accessible for them, press releases ad general public awareness campaigns have been organised, the project website used as a communication tool inside the Consortium kept updated and collected the main dissemination material and activities arranged.
A workshop about biodegradable multilayer package was hold in AIMMPLAS, and presented PLA4FOOD package as a success case study.
Several stakeholders have expressed their interest in the project contacting the general email: info through the project website, such as: Polymer (plastic transformer form Costa Rica), Plasticos Boulevares (Bolivia), Roger de Lauria (Cooking Training school), PhD students, etc. They have been invited and some of them attended the workshop organised in AIMPLAS to disseminate the project results.
The training material was collected in a two versions document D9.4 Best practice Guidelines, the public version gathered all the material about general processes carried out in the project, specific information about the PLA4FOOD project was included in the confidential version. The training event was arranged as part of a General Assembly meeting in Frankfurt, several material has been exchanged with the SME partners via email or conference calls in order to assist them during the scaling-up phase.
WP10. Management
After Period 1 the person in charge of the project - Mr Nuri Akkas - left the company due to healthy issues. From that date, he was replaced by Mr Ahmet Sumer, who had been lightly involved in PLA4FOOD activities during P1. Mr Sumer, became therefore responsible for technical and managerial issues related to PLA4FOOD. Since this change of responsible in TROYKA, communication became difficult with this Partner, and the problem has been increasingly worse. Lately he is not replying to emails, phone calls, neither signing letters to approve RTDs work and not attending any meeting.
The Consortium declare partner TROYKA defaulting party and the Coordinator send them a letter on behalf of the consortium asking for their costs statement or transferring the not approved funds to the project bank account.
All this impacted the Project activities because TROYKA, as end user of PLA4FOOD packages, should validate the fruit package developed in the project. Finally, an amendment was submitted to the EC, terminating TROYKA participation on the 1st December 2011 and internally redistributing TROYKA old tasks, most of them have been assumed by DOMCA.
Apart from the issue with partner TROYKA a fluent communication among the partners and the REA has been maintained during this period.
The scaling up process (WP7) has been several months delay due to the temporary lack of materials in the suppliers store, for this reason the acquisition time was longer than expected, additionally both technicians responsible for the project in ALESCO and POLYRAZ, the two SMEs involved in the scaling-up, have left respectively the companies, when shipment to or from Israel were arranged took more than expect due to customs service delays.
Deliverables due on this period were submitted on due time according to the annex I version 27/05/2013, as it is summarized in Table XIV.
Problems which have occurred and how they were solved or envisaged solutions;
RTD performer TECHNION asked for a budget transfer of 3.000 € from DEMO to RTD, this shift has been already approved by all the SMEs and reflected in WP 7. The subcontracting requested and allocation in the invoices from RTD to SME will remain unchanged as expected and detailed in the Annex I.
Changes in the consortium, if any;
TROYKA was declared defaulting party and a letter was sent to them asking for their costs statement, unfortunately no feedback was received, an amendment was consequently submitted to the EC, informing about this change in the Consortium.
List of project meetings, dates and venues;
Table XIII collects information about the meetings arranged during the 18 months of this reported period (01/12/2011-31/05/2013)
Date 11/01/2012 Purpose: Technical meeting – review of actions to face the scale up Location: TECHNION, Israel Participants: STRAUSS and TECHNION
Date 09/05/2012 Purpose: 18th month meeting Location: ICT, Germany Participants: All partners except: POLYRAZ, PROYMEC and TROYKA
Date 28-29/11/2012 Purpose: GA meeting Location: Frankfurt, Germany Participants: All partners except: POLYRAZ, PROYMEC, STRAUSS and TROYKA
Date 08/03/2013 Purpose: Technical meeting Location: AIMPLAS, Spain Participants: AIMPLAS, DOMCA, ADDCOMP, TECHNION and FRAUNHOFER
Further conference calls have been arranged between the partners in the Consortium to discuss technical and managerial issues, such as, the ones hold on the dates 03/02/2012; 05/03/2012, 26/03/2012, 13/04/2012, 24/04/2012, 29/05/2012, 10/07/2012, 11/10/2012, 07/11/2012, 11/01/2013, 30/01/2013, 04/02/2013, and 13/05/2013.
The minutes, presentations and further details about the meetings are available in the project website: http://www.aimplas.es/proyectos/pla4food/
Project planning and status;
Due to the delays caused by the raw materials stock, customs services and changes of the responsible technicians, WP7 was developed with approximately one month of delay according to the foreseen timing from Annex I.
Impact of possible deviations from the planned milestones and deliverables, if any;
All deliverables were submitted in some cases with deviations comparing to the timing, but reflecting the good results achieved in the project and the excellent package properties.
Any changes to the legal status of any of the beneficiaries, in particular non-profit public bodies, secondary and higher education establishments, research organisations and SMEs;
Not applicable
Development of the Project website, if applicable;
Further information about this topic can be found in the WP 9 ‘Dissemination, exploitation and training’. The project web site: http://www.aimplas.es/proyectos/pla4food/ is working properly since the early stages of the project. The contents on the private section have been increasing in relation to the project development.
Use of foreground and dissemination activities during this period (if applicable).
The final version of this document has been submitted to the REA together with the PPR in P2. The document aforementioned includes also the complete list of the dissemination activities carried out since the starting date of the project.
Consortium
Except the communication matter with TROYKA during the last P2, a fluent communication among the partners has been maintained during this period and also a good response when arranging meetings and with the meeting attendance has been received.
When some of the partners were not able to attend meeting different conference calls between the RTD performers and this partner took place after it.
A successful communication inside the Consortium has been shown when required, for example, declaration of TROYKA as defaulting party, approval of dissemination material (poster, project presentation, articles, etc), website comments; approval of budget shift of RTD performer.
REA
A fluent communication has been maintained with the REA highlighting the following issues:
- Assistance with the P1 Periodic Project Report submission and Form Cs delivery
- Approval of P1 reports and intermediate transfer
- Assistance with the cost category related to RTD performer: TECHNION
- Advices when communicating about the delays in the project
- New Project Officer has been assigned
- Amendment and procedure to follow with partner TROYKA termination
Potential Impact:
Fresh-cut fruits and vegetables exemplify the consumer driven products that have evolved from commodities to cater to European consumers’ increasing demand for healthy and easy-to-prepare foods. For vegetable and fruit producers/shippers, fresh-cut products have become a way to add value to their commodity products.
The demand for healthy and convenient products and advances in packaging technology has driven the expansion of the fresh-cut industry.
Gradually, the supermarket selection has expanded from just a bag of lettuce to mixed vegetables, complete salads and complete ready-to-eat meal components.
Growth in the consumption of fresh-cut products is expected to continue by close to 10% per year. The drivers for the increase in consumption of fresh-cut products in Europe are the rise in income levels, the increase in health consciousness, and the demand for convenience.
With extra discretionary income, consumers will spend more on quality and convenience food products. In general, produce consumption is also expected to increase due to growing awareness of the correlation between diet and health, and of the nutritional benefits of fruits and vegetables.
The emerging fresh-cut fruit sector will likely overshadow salad sales in the future because fresh-cut fruits are more attractive to young consumers and aging baby boomers and in general are more likely to be consumed as snack products.
Packaging has achieved ubiquitous presence on people’s daily life as confirmed in several market and economic reports providing indicators that reflect a constant growth during the last years, predicting as well a 6-10% yearly growth of packaging demand for the coming years. Particularly, food packaging has the highest percentage of consumption, representing the 52% of the world packaging market share with a market volume of 47 billion Euros in Europe . Food packaging has grown a 4% during 2008 being plastics the most consumed material for food packaging manufacture due to the wide range of possible combinations of polymers, additives and transformation processes, which makes them the most versatile material referring to shapes, costs and final properties of the package.
Plastic food packaging continues to be dominated by flexible formats (more than 65% of total plastic packaging sector) used for confectionery, bakery, savoury snacks and ice cream products . The most dynamic category among flexible packaging is pouches – used increasingly for sauces and other retorted foods due to their convenient format. The plastic flexible packaging market invoicing 20 billion Euros in Europe and generate around 100.000 employments. This sector is composed by around 7.000 companies, 85% of SMEs
Relevance to other industrial sectors.
• According to European Bioplastics, the total capacity of bioplastics (compostable and non compostable) by the end of 2011 was more than 1100 kt. That represents almost 5 time more compared 2009. The expected forecast in 2016 will be close to 5800 kt.
• The global polylactic acid (PLA) market is expected to grow at an annual compounded rate of 28% for the period 2011-2026, reaching USD 2.6bn. Europe follows at a CAGR of 28.9%, with the Americas expected to achieve 27.3%. According to Germany’s nova-Institut , the global PLA capacity could exceed 800,000 t/y by 2020 .
• Farmers obtaining a direct profit from this project. This can open new sales ways to their products in high added value markets. The possibilities to enlarge the shelf life of fresh cut products will lead to production delocalization to reach far away customers and in consequence to increase the competitiveness of their products. Additionally, natural additives are obtained for agricultural waste or aromatic plants, PLA4FOOD will help to valorize them.
The estimated time-to-market is up to two years after the end of the project, ensuring the quick commercialization of the project results and potential products.
The project results have been summarized in the list below:
Exploitable results / IPR Protection / Owner(s)
R1: Microencapsulation technology of active additives based on zeolites / Industrial Secret / 70% DOMCA + 30% ADDCOMP
R2: PLA formulation for the outer layers based on OLA, organic/inorganic nucleants and water scavengers / Industrial Secret / 40% ADDCOMP + 30% ALESCO + 30% POLYRAZ
R3: PLA formulation for the inner layer based on OLA and active additives / Industrial Secret / 20%DOMCA + 30% ADDCOMP + 25% ALESCO + 25% POLYRAZ
R4: Multilayer active package for fresh-cut products with controlled release kinetics / Industrial Secret / 15%DOMCA + 35% ALESCO + 35% POLYRAZ + 15% TROYKA
R5: Packaging plant design for optimal use of the new package specifications / Industrial Secret / 100 % PROYMEC
List of Websites:
http://www.aimplas.es/proyectos/pla4food
Contact
AIMPLAS - Instituto Tecnológico del Plástico
C/ Gustave Eiffel, 4 (València Parc Tecnològic) | 46980 - PATERNA (Valencia) – SPAIN
(+34) 96 136 60 40
info.pla4food@aimplas.es
