Final Report Summary - TRAYSRENEW (Development of innovative renewable trays for poultry products, based on biopolymers and bast fibers)
Executive Summary:
Food and beverages represent 16.8% of household expenditure in Europe , with meat comprising over one quarter of this. One case is poultry products which constitutes 25% of the meat consumption in Europe. Poultry is considered by consumers as healthy, inexpensive, low in fat and a high nutritious source of protein. Competitive prices to other meats and strong consumer preference are projected to drive the EU poultry production to 12,5 million tonnes by 2015 (+8,8%). Poultry consumption is projected to increase at the higher rate of 9,4% by 2015 and globally, the projected consumption and production would increase from 98 million tonnes in 2009 to 120 million tonnes in 2017. However, poultry is a highly perishable food and the time it takes to deteriorate varies from 4 up to 10 days after slaughtering, in spite of having been stored under chill systems . Extending the shelf life of poultry products is a major concern for the industry. Main functions of a packaging are to preserve, to protect, to inform and to transport the products which contain. When we consider the packaging materials, a single polymer is often unable to provide a suitable barrier; because of that most food packaging materials are multilayer constructions. In multilayer constructions polymers with different barrier properties are combined, where at least one layer acts as an oxygen barrier, other act as water barrier and other layers have sealing properties. Currently commercial packaging materials are derived from petroleum sources, besides its recycling processes are costly due to its different origins and the difference of suitable end-of-life treatments for each material type.
In Europe, there is a strong interest to find out where bio-based products can be used in packaging applications. According to European Bioplastics, in 2009, global production of bioplastics comprised approximately 400.000 tons of the total 260 million ton plastics market, maximum technical substitution potential of bio-based polymers replacing their petrochemical counterparts is estimated at 90% of the total polymers. However, biodegradable polymers are much more expensive than existing polymers such as PET or PS, and their properties are not comparable, yet.
One possible route to decrease costs and increase properties in raw biodegradable polymers is the development of biocomposites. Composite materials are engineered materials made from two or more constituent materials with significantly different physical or chemical properties. Biocomposites are defined as composite materials comprising more than one phase derived from a biological origin: a matrix which is a biodegradable material, and a reinforcement phase, that can be a cellulose fibre. These fibres provide strength and stiffness and act as reinforcement in fibre-reinforced composite materials, increasing the properties of raw polymers and helping for the final material biodegradation.
The TRAYSRENEW concept is to develop a new biodegradable packaging for poultry products, based on biopolymers (up to 85%), flax and hemp micro or nanometer scale fibres (up to 15%) and biodegradable additives to modify the overall composite properties. The use of micro and nanofibres will led to an increase in properties of the raw materials, achieving a new biodegradable material that could fulfill the properties required for the proper conservation of the selected food. These properties include permeability to gases (carbon dioxide, oxygen, water vapour), sealability, mechanical properties (tensile, puncture resistance), and the main important, to accomplish with food safety regulations.
With the TRAYSRENEW development the consortium will develop a new sustainable packaging solution for being used in a future for other meat applications. This solution could be launched onto the market in one year after the project finalization.
Project Context and Objectives:
TRAYSRENEW project has a high innovative character and will enhance significantly the state-of-the-art in the poultry packaging area. Current solutions cannot meet the demand and the other research approaches are too long term.
Therefore TRAYSRENEW project has an opportunity to exploit its innovative approach; however, some scientific and technological barriers have been overcome during the project development, such as:
▪ Selection of the most appropriate fibres to develop the new packaging material. Depending on the source (hemp or flax), location of the farming, fibre dimensions and composition selected fibres were different. Several analyses have been performed in order to select the most appropriated for the development of composite materials.
▪ Compatibility of fibres with the polymeric matrices selected. Fibres are highly polar and hydrophilic, making them prone to a loss of mechanical properties upon atmospheric moisture adsorption (e.g. from the open end of a sectioned piece of composite material).Specific surface modifications to decrease their water uptake and increase compatibility with the matrix have been evaluated, all of them using food contact approval additives, obtaining modified fibres with good adhesion properties.
▪ Properties improvement through proper dispersion. The dispersion of fibres within the matrix must be uniform in order to develop a material with suitable characteristics. After the surface modification development, processing steps have been adjusted, optimising the blending of a matrix with its reinforcing phase and finally obtaining composites with improved properties.
Project results could be divided as followed:
1. Selection of fibres to obtain cellulose nanowhiskers and cellulose nanowhiskers modification
A wide attention is currently being dedicated to the use of natural fibres as reinforcement for polymeric packaging materials. The fundamental advantage of employing natural fibres to reinforce plastic composites is that these are biodegradable and renewable, exhibit low cost, low density, high toughness and have a good thermal resistance. Moreover, polymer materials reinforced with natural fibres can combine satisfactory mechanical and barrier properties with a low specific mass. The majority of plant fibres which are being considered as reinforcements for polymeric materials are bast fibres, defined as fibres obtained from the outer cell layers of the stems of various plants. Natural bast fibres, such as flax and hemp have received considerable attention for their use in composites due to their specific strength, modulus properties and availability. These fibres have more or less similar morphologies and could have similar mechanical and barrier functions to develop new composites with enhanced properties. In TRAYSRENEW project both fibre chemical compositions of cellulose, lignin, holocellulose, hemicellulose, ash content, as well as extractive substances in different solvent systems have been studied according to TAPPI Standard Norms. Flax cellulose content is higher that Hemp cellulose content; (69% vs 20% respectively) and also has less lignin content. This evaluation was very important in order to decide which is the most appropriate to be used as raw material for cellulose nanowhiskers isolation. Different pre-treatments and processing stages have been studied in order to evaluate how affect its final chemical composition, and which is the optimum chemical fibre treatment for obtaining nano and micro fibres with good surface compatibility and as a consequence, good behaviour within the polymeric matrix for producing the composites. The procedure to obtain cellulose nanowhiskers was based on acid treatments and finally two chemical modifications by using silane and acetylated agents were developed. Modified fibres showed an improvement in its compatibility compared with non-modified fibres.
2. Definition of most appropriated composites processing parameters and selection of biocomposites
Biopolymers used in TRAYSRENEW project were poly (lactid acid) (PLA), poly (hidroxyalkanoates) (PHBV) and thermoplastic starch (TPS). During the project some processing technologies and different additives have been evaluated in order to accomplish TRAYSRENEW project final objective. First of all, different biocomposites using these biopolymers and the modified fibres developed in WP1 were developed by extrusion at laboratory scale. To improve fibre-polymer adhesion and to help in extrusion processes different coupling agents and processing additives have been used. After its processing parameters optimization, developed biocomposites properties have been characterized by mechanical, thermal and barrier analyses.
For PLA, obtained results can be stated that modified nanofibres incorporation into the matrix result in materials with higher tensile strength and elastic modulus. Results are not very different for 3 or 5 wt% of modified nanofibres. Better results were obtained using silane-modified. Strain and Break results indicated that a plasticizer could be required in for increasing the elongation of PLA in all biocomposites.
TPS results showed an increase in mechanical properties due to the incorporation of cellulose nanofibres, different coupling agents were tested and some of them lead to a high plastification in the material, causing a decrease on the yield strength (YS) and other mechanical parameters; In general, TPS results showed lower properties than those obtained for PLA biocomposites.
PHBV was evaluated using different processing parameters and additives, however, this material showed many processing issues which made it difficult to process (ex: low melt strength) ; so it was decided to discard this polymer.
All properties were very important for the new material development, but barrier properties were the limiting factor for taking a decision about the final biocomposite selection. In general, results show improvements after the inclusion of modified nanofibres compared with the neat biopolymers properties; oxygen barrier permeability and water vapour permeability values are better in both polymers (PLA and TPS). However, best mechanical and barrier properties have been obtained with PLA reinforced with silane modified nanofibres, so this material has been selected as the most promising to obtain the sheet and the top lid.
3. Development of the sheet and the top film
The process to obtain a sheet and a lid are based on extrusion process. This is a continuous operation of melting and conveying a polymer into a screw through a heated barrel. The homogenous melt is forced to flow through a sheet die from which it leaves in the desired width and thickness. The obtained sheet is then cooled further on a cooling conveyor while the edges are trimmed to final sheet width. The sheet is usually rolled for later use.
If during the extrusion process it is looking for a high resistance sheet, co-extrusion is a quite powerful technique to increase material properties; in this project co-extrusion is consider to obtain a sheet with the required mechanical properties. TRAYSRENEW development had combined two or more molten polymer layers into a composite extruded sheet which provides enhanced properties when compared to monolayer materials and also can reduce the number of process operations required when several polymers are needed to obtain the desired properties.
To obtain TRAYSRENEW top-lid film cast film co-extrusion was also used. With this technique the production of wide width films is more easily controlled than in the blown film process. Higher take off speeds are possible, reducing costs for film production. In addition, cast film extrusion offers better gauge control and gauge consistency.
When considering applications with higher barrier requirements, development of multilayer structures is usually a must. In TRAYSRENEW project several multilayer structure designs have been evaluated. Previously, each composite sheet and top-lid properties have been characterized, tensile, thermal and barrier properties, food safety and biodegradability rates. These results have been used to design the most appropriated multilayer structure in terms of mechanical resistance, barrier requirements and food contact assessment. Finally TRAYSRENEW sheet and top-film have 3 layers (ABA), all of them made by biodegradable materials and fibre-PLA biocomposites.
4. Development of thermoformed trays and upscale
Thermoforming steps are crucial to determine the final packaging properties, mainly mechanical and barrier properties. Thermoforming is the process of forming a thermoplastic sheet into a three dimensional shape (or a tray).
To obtain good thermoformed trays, as example, there are some parameters which have to be controlled such as:
1- Type of material and its behavior: In our case biodegradable semi-crystalline polymers such as PLA and its biocomposites. It is very important to control polymer thermal properties, which are one of the most relevant critical aspects of the process. PLA has lower Tg and softening temperature than PET or PS and also an intrinsic thermal conductivity lower than polystyrene and PET. These factors, for example indicate that the cooling time in the mould will be greater for PLA than either PS or PET. Fillers and fibres increase polymer stiffness but usually not polymer transition temperatures, however, do affect the thermal properties of the sheet. Therefore, these parameters have been adjusted for each web structure evaluated within the project.
2- Type of thermoforming process: vacuum-forming, pressure-forming and plug assisted thermoforming. The type of thermoforming used has different material conditions requirements that could be optimized in each processing step: Also, there are materials that couldn´t be used for specific thermoformed processes. In TRAYSRENEW project a vacuum-thermoformed process was used.
3- Type of mould: male, female, matched moulds. Depending of the mould type different adjust in the materials could be performed. In TRAYSRENEW a male or positive mould.
To obtain TRAYSRENEW final thermoformed trays, all these conditions have been evaluated and processing parameters such as time, temperature, pressure and speed have been optimized. A specific mould has been designed considering tray format used at the company “Productos Florida” being able to use at their facilities.
All thermoformed trays have been characterized, analyzing different properties such as:
- Wall thickness distribution:
- Optical microscopy evaluation
- Sealability test
- Mechanical properties (compression)
- Thermal properties
- Oxygen and water vapour transmission rate
Poultry shelf-life study in the new developed trays
The shelf-life of meat packaged using modified atmosphere packaging (MAP) depends on gas concentrations, and other factors, including storage temperature, initial contamination degree, materials permeability to gases (oxygen, carbon dioxide, water), and the headspace volume in the packaging. Freshness and shelf-life are affected by the inherent properties of the product just as much as by external factors such as the type and quantity of microorganism, water activity raw, pH value and so on....
The final result of TRAYSRENEW project is a fully evaluation of poultry shelf-life by using the developed packaging. To decide the final packaging system four different systems have been evaluated, using two different types of trays and top-lids. Chicken breast was packaged in the facilities of Productos Florida, located in Almassora (Valencia, Spain) using a fully automated tray sealing unit. During the trials, several machine parameters such as, temperature and time of sealing parameters time and web tension have been adequate to the new packaging materials; all necessary poultry trials samples have been obtained and tested.
Shelf-life evaluation
During spoilage, different metabolites are released from the product due to both microbial and enzymatic spoilage. The point of spoilage is usually defined as the maximum acceptable bacterial level and/or when meat reaches an unacceptable odour/flavour or appearance for consumption. However the most common indicators of spoilage are off odour, discoloration and production of gases.
To identify the first signs of meat alteration, different indicators were proposed for consideration, most important being headspace, pH, lipids oxidation products, colour, and microbiological counts. The evaluation was very satisfactory, headspace gas evaluation and pH tests showed correct parameters until 10 days.
An excessive oxidation of muscle lipids can produce compounds that adversely affect the quality of meat. These compounds are in some cases associated to off-flavours and off-odours, loss of colour, vitamins, lower consumer acceptability and also affect the safety of meat. To measure the oxidation degradation process two different techniques were used: TBA and Hexanal parameters analysis. Both results indicate that all combination of trays and lids get over 7 days and one of them could be arrive until 9-10 days.
Microbiological evaluation
Microbial contamination of the muscles starts at the point of slaughter. Contamination from the external surface of the carcass, internal gastrointestinal tracts, faeces and from the environment such as the slaughterhouse and equipment used for slaughtering can determine the initial composition and load of spoilage microorganism on the meat.
The spoilage of raw poultry is mainly caused by microbial growth, aerobic spoilage bacteria are very effectively inhibited by CO2 in MAP and refrigerated storage. Three main microorganism tests were evaluated; Enterobacteriaceae that is a large group of bacteria involving many foodborne pathogens, including pathogenic Escherichia coli, Shigella, Salmonella, Yersinia and many others. E. coli and total aerobic Mesophyll (TAM) which is a big group of bacteria able to grow at warms temperature (between 20 and 45ºC), and they include bacterium of different families without other relationship than temperature. All combinations show good behavior until 8 days.
Sensory evaluation
Finally, the sensory evaluation of the chicken breast was performed by evaluating the odor and the appearance of this product. Trained personnel were used for sensory analysis. Chicken breasts were evaluated using a pass-no pass criteria. The properties used in the evaluations were total intensity of the odor, appearance and drip. All samples passed the sensory analysis, although the evaluated packaging solution is an experimental design that could be implemented to avoid for example the formation of exudates in the bottom of the tray, which was the only negative aspect.
Summarizing the entire obtained results TRAYSRENEW consortium is satisfied and the main objectives have been accomplished during the project, nonetheless, some improvements in the upscale of fibres, optimized of up scaling materials processing processes and finally in the packaging system design will be implemented in further projects.
Project Results:
Poultry sector it has gained importance and its market has been the most dynamic in the last decade increasing its production each year since 1999. Medium terms prospects remain positive with an increased consumption of poultry and pigmeat compared with other meals. Globally, the projected consumption and production would increase from 98 million t in 2009 to 120 million t in 2017 especially in the developing countries where growing incomes increase the demand for meat (82% of the projected global growth) according to FAO.
Bioplastics market is being promoted during the last years due to numerous causes such as the increasing of crude oil price and its variability, the eco-friendly awareness of consumers, producers and transformers and so on. Thus, it is increasing the demand and the pressing for the plastic industry branch (worth EUR 200 billion in all sectors of Europe) to use alternative raw materials. Currently, available bioplastics types cover approx. 5-10% of the plastics market. Bioplastics development is just beginning and their market share is well under one-three percent (consumption estimated by the Association: approx. 50 000t in Europe). The market is growing and in many application areas such as packaging, the quantity of the demand and the number of bioplastics types and alternatives is increasing dramatically.
In addition, the price of bioplastics has continued to fall over the past ten years. Their competitiveness over conventional plastics should also continue to improve into the future through more effective processes, possible economies of scale and simultaneous increasing competition from new market players. New bioplastics grades have been developed presenting better properties and more functionalities than older grades. So the annual growth is considerably higher than 20%.
The economic impact of each SME after the development of TRAYSRENEW project is been estimated as positive. First’s considerations were based in the amount of consumed poultry and the expected increase, following by the specific amount of this poultry that is packaged, aprox: 3.542.223.000 kg by 2016. With this conservative estimation the number of packaging that will be sold at 2016 is around 17.712.000.000 units, with only a market quote of 0.5% in 2014 and 2% in 2016 the estimated number of packaging units that will be sold in 2016 will be around 662 million. Despite of TRAYSRENEW solution is more expensive than conventional packaging materials solutions the forecast will be positive, and besides this solution is cheaper than 100% bioplastics packaging solutions.
Considering that the application will mature through the years, we expect to absorb the benefits of economies of scale in order to reduce the cost further. Moreover, the cost of hydrocarbons as a raw material is likely to increase and, as a consequence, prices of conventional plastics too. This way, we expect to reduce the prices difference existing between plastics coming from petroleum based materials and our solution. And also, this application will be implemented in order to be suitable for other food products.
So, the consortium believes that there is potentially a very large economic benefit to Europe and the SME consortium members. The assumptions which have been made for predicting the future market of the final product have been done taking into account the external influences. These external influences include compliance with regulations, market place credibility and competition. We have evaluated these risks and evaluated their commercial impact on the project, all the defined risk have been overcome by the expertise and knowledge of the research centers involved in the project (ITENE, EHU and MATRI) and the widely know-how and professionalism of each SME of the consortium (Termoformas Levante, Rodenburg Biopolymers, Rondol technology, Gaviplas, Artic Fiber and La Florida).
Regarding exploitation results all the IPR results have been managed by the consortium including two different types of patentable technology and tray design.
Several dissemination activities have been carried out such two strategic conferences organized by TRAYSRENEW members, the participation in trade fairs and conferences related to packaging (for example, HISPACK, INTERPACK, IAPRI) and other publications such as a project brochure, several press release, posters and other publications in scientific journals, in addition the project webpage have been used as a platform to share all the public information.
Potential Impact:
Poultry sector it has gained importance and its market has been the most dynamic in the last decade increasing its production each year since 1999. Medium terms prospects remain positive with an increased consumption of poultry and pigmeat compared with other meals. Globally, the projected consumption and production would increase from 98 million t in 2009 to 120 million t in 2017 especially in the developing countries where growing incomes increase the demand for meat (82% of the projected global growth) according to FAO.
Bioplastics market is being promoted during the last years due to numerous causes such as the increasing of crude oil price and its variability, the eco-friendly awareness of consumers, producers and transformers and so on. Thus, it is increasing the demand and the pressing for the plastic industry branch (worth EUR 200 billion in all sectors of Europe) to use alternative raw materials. Currently, available bioplastics types cover approx. 5-10% of the plastics market. Bioplastics development is just beginning and their market share is well under one-three percent (consumption estimated by the Association: approx. 50 000t in Europe). The market is growing and in many application areas such as packaging, the quantity of the demand and the number of bioplastics types and alternatives is increasing dramatically.
In addition, the price of bioplastics has continued to fall over the past ten years. Their competitiveness over conventional plastics should also continue to improve into the future through more effective processes, possible economies of scale and simultaneous increasing competition from new market players. New bioplastics grades have been developed presenting better properties and more functionalities than older grades. So the annual growth is considerably higher than 20%.
The economic impact of each SME after the development of TRAYSRENEW project is been estimated as positive. First’s considerations were based in the amount of consumed poultry and the expected increase, following by the specific amount of this poultry that is packaged, aprox: 3.542.223.000 kg by 2016. With this conservative estimation the number of packaging that will be sold at 2016 is around 17.712.000.000 units, with only a market quote of 0.5% in 2014 and 2% in 2016 the estimated number of packaging units that will be sold in 2016 will be around 662 million. Despite of TRAYSRENEW solution is more expensive than conventional packaging materials solutions the forecast will be positive, and besides this solution is cheaper than 100% bioplastics packaging solutions.
Considering that the application will mature through the years, we expect to absorb the benefits of economies of scale in order to reduce the cost further. Moreover, the cost of hydrocarbons as a raw material is likely to increase and, as a consequence, prices of conventional plastics too. This way, we expect to reduce the prices difference existing between plastics coming from petroleum based materials and our solution. And also, this application will be implemented in order to be suitable for other food products.
So, the consortium believes that there is potentially a very large economic benefit to Europe and the SME consortium members. The assumptions which have been made for predicting the future market of the final product have been done taking into account the external influences. These external influences include compliance with regulations, market place credibility and competition. We have evaluated these risks and evaluated their commercial impact on the project, all the defined risk have been overcome by the expertise and knowledge of the research centers involved in the project (ITENE, EHU and MATRI) and the widely know-how and professionalism of each SME of the consortium (Termoformas Levante, Rodenburg Biopolymers, Rondol technology, Gaviplas, Artic Fiber and Productos Florida).
Regarding exploitation results all the IPR results have been managed by the consortium including two different types of patentable technology and tray design. Several dissemination activities have been carried out; one strategic conferences organized by TRAYSRENEW members, and project brochure, several press release, posters and other publications in scientific journals, in addition the project webpage have been used as a platform to share all the public information.
List of Websites:
www.traysrenew.eu
Food and beverages represent 16.8% of household expenditure in Europe , with meat comprising over one quarter of this. One case is poultry products which constitutes 25% of the meat consumption in Europe. Poultry is considered by consumers as healthy, inexpensive, low in fat and a high nutritious source of protein. Competitive prices to other meats and strong consumer preference are projected to drive the EU poultry production to 12,5 million tonnes by 2015 (+8,8%). Poultry consumption is projected to increase at the higher rate of 9,4% by 2015 and globally, the projected consumption and production would increase from 98 million tonnes in 2009 to 120 million tonnes in 2017. However, poultry is a highly perishable food and the time it takes to deteriorate varies from 4 up to 10 days after slaughtering, in spite of having been stored under chill systems . Extending the shelf life of poultry products is a major concern for the industry. Main functions of a packaging are to preserve, to protect, to inform and to transport the products which contain. When we consider the packaging materials, a single polymer is often unable to provide a suitable barrier; because of that most food packaging materials are multilayer constructions. In multilayer constructions polymers with different barrier properties are combined, where at least one layer acts as an oxygen barrier, other act as water barrier and other layers have sealing properties. Currently commercial packaging materials are derived from petroleum sources, besides its recycling processes are costly due to its different origins and the difference of suitable end-of-life treatments for each material type.
In Europe, there is a strong interest to find out where bio-based products can be used in packaging applications. According to European Bioplastics, in 2009, global production of bioplastics comprised approximately 400.000 tons of the total 260 million ton plastics market, maximum technical substitution potential of bio-based polymers replacing their petrochemical counterparts is estimated at 90% of the total polymers. However, biodegradable polymers are much more expensive than existing polymers such as PET or PS, and their properties are not comparable, yet.
One possible route to decrease costs and increase properties in raw biodegradable polymers is the development of biocomposites. Composite materials are engineered materials made from two or more constituent materials with significantly different physical or chemical properties. Biocomposites are defined as composite materials comprising more than one phase derived from a biological origin: a matrix which is a biodegradable material, and a reinforcement phase, that can be a cellulose fibre. These fibres provide strength and stiffness and act as reinforcement in fibre-reinforced composite materials, increasing the properties of raw polymers and helping for the final material biodegradation.
The TRAYSRENEW concept is to develop a new biodegradable packaging for poultry products, based on biopolymers (up to 85%), flax and hemp micro or nanometer scale fibres (up to 15%) and biodegradable additives to modify the overall composite properties. The use of micro and nanofibres will led to an increase in properties of the raw materials, achieving a new biodegradable material that could fulfill the properties required for the proper conservation of the selected food. These properties include permeability to gases (carbon dioxide, oxygen, water vapour), sealability, mechanical properties (tensile, puncture resistance), and the main important, to accomplish with food safety regulations.
With the TRAYSRENEW development the consortium will develop a new sustainable packaging solution for being used in a future for other meat applications. This solution could be launched onto the market in one year after the project finalization.
Project Context and Objectives:
TRAYSRENEW project has a high innovative character and will enhance significantly the state-of-the-art in the poultry packaging area. Current solutions cannot meet the demand and the other research approaches are too long term.
Therefore TRAYSRENEW project has an opportunity to exploit its innovative approach; however, some scientific and technological barriers have been overcome during the project development, such as:
▪ Selection of the most appropriate fibres to develop the new packaging material. Depending on the source (hemp or flax), location of the farming, fibre dimensions and composition selected fibres were different. Several analyses have been performed in order to select the most appropriated for the development of composite materials.
▪ Compatibility of fibres with the polymeric matrices selected. Fibres are highly polar and hydrophilic, making them prone to a loss of mechanical properties upon atmospheric moisture adsorption (e.g. from the open end of a sectioned piece of composite material).Specific surface modifications to decrease their water uptake and increase compatibility with the matrix have been evaluated, all of them using food contact approval additives, obtaining modified fibres with good adhesion properties.
▪ Properties improvement through proper dispersion. The dispersion of fibres within the matrix must be uniform in order to develop a material with suitable characteristics. After the surface modification development, processing steps have been adjusted, optimising the blending of a matrix with its reinforcing phase and finally obtaining composites with improved properties.
Project results could be divided as followed:
1. Selection of fibres to obtain cellulose nanowhiskers and cellulose nanowhiskers modification
A wide attention is currently being dedicated to the use of natural fibres as reinforcement for polymeric packaging materials. The fundamental advantage of employing natural fibres to reinforce plastic composites is that these are biodegradable and renewable, exhibit low cost, low density, high toughness and have a good thermal resistance. Moreover, polymer materials reinforced with natural fibres can combine satisfactory mechanical and barrier properties with a low specific mass. The majority of plant fibres which are being considered as reinforcements for polymeric materials are bast fibres, defined as fibres obtained from the outer cell layers of the stems of various plants. Natural bast fibres, such as flax and hemp have received considerable attention for their use in composites due to their specific strength, modulus properties and availability. These fibres have more or less similar morphologies and could have similar mechanical and barrier functions to develop new composites with enhanced properties. In TRAYSRENEW project both fibre chemical compositions of cellulose, lignin, holocellulose, hemicellulose, ash content, as well as extractive substances in different solvent systems have been studied according to TAPPI Standard Norms. Flax cellulose content is higher that Hemp cellulose content; (69% vs 20% respectively) and also has less lignin content. This evaluation was very important in order to decide which is the most appropriate to be used as raw material for cellulose nanowhiskers isolation. Different pre-treatments and processing stages have been studied in order to evaluate how affect its final chemical composition, and which is the optimum chemical fibre treatment for obtaining nano and micro fibres with good surface compatibility and as a consequence, good behaviour within the polymeric matrix for producing the composites. The procedure to obtain cellulose nanowhiskers was based on acid treatments and finally two chemical modifications by using silane and acetylated agents were developed. Modified fibres showed an improvement in its compatibility compared with non-modified fibres.
2. Definition of most appropriated composites processing parameters and selection of biocomposites
Biopolymers used in TRAYSRENEW project were poly (lactid acid) (PLA), poly (hidroxyalkanoates) (PHBV) and thermoplastic starch (TPS). During the project some processing technologies and different additives have been evaluated in order to accomplish TRAYSRENEW project final objective. First of all, different biocomposites using these biopolymers and the modified fibres developed in WP1 were developed by extrusion at laboratory scale. To improve fibre-polymer adhesion and to help in extrusion processes different coupling agents and processing additives have been used. After its processing parameters optimization, developed biocomposites properties have been characterized by mechanical, thermal and barrier analyses.
For PLA, obtained results can be stated that modified nanofibres incorporation into the matrix result in materials with higher tensile strength and elastic modulus. Results are not very different for 3 or 5 wt% of modified nanofibres. Better results were obtained using silane-modified. Strain and Break results indicated that a plasticizer could be required in for increasing the elongation of PLA in all biocomposites.
TPS results showed an increase in mechanical properties due to the incorporation of cellulose nanofibres, different coupling agents were tested and some of them lead to a high plastification in the material, causing a decrease on the yield strength (YS) and other mechanical parameters; In general, TPS results showed lower properties than those obtained for PLA biocomposites.
PHBV was evaluated using different processing parameters and additives, however, this material showed many processing issues which made it difficult to process (ex: low melt strength) ; so it was decided to discard this polymer.
All properties were very important for the new material development, but barrier properties were the limiting factor for taking a decision about the final biocomposite selection. In general, results show improvements after the inclusion of modified nanofibres compared with the neat biopolymers properties; oxygen barrier permeability and water vapour permeability values are better in both polymers (PLA and TPS). However, best mechanical and barrier properties have been obtained with PLA reinforced with silane modified nanofibres, so this material has been selected as the most promising to obtain the sheet and the top lid.
3. Development of the sheet and the top film
The process to obtain a sheet and a lid are based on extrusion process. This is a continuous operation of melting and conveying a polymer into a screw through a heated barrel. The homogenous melt is forced to flow through a sheet die from which it leaves in the desired width and thickness. The obtained sheet is then cooled further on a cooling conveyor while the edges are trimmed to final sheet width. The sheet is usually rolled for later use.
If during the extrusion process it is looking for a high resistance sheet, co-extrusion is a quite powerful technique to increase material properties; in this project co-extrusion is consider to obtain a sheet with the required mechanical properties. TRAYSRENEW development had combined two or more molten polymer layers into a composite extruded sheet which provides enhanced properties when compared to monolayer materials and also can reduce the number of process operations required when several polymers are needed to obtain the desired properties.
To obtain TRAYSRENEW top-lid film cast film co-extrusion was also used. With this technique the production of wide width films is more easily controlled than in the blown film process. Higher take off speeds are possible, reducing costs for film production. In addition, cast film extrusion offers better gauge control and gauge consistency.
When considering applications with higher barrier requirements, development of multilayer structures is usually a must. In TRAYSRENEW project several multilayer structure designs have been evaluated. Previously, each composite sheet and top-lid properties have been characterized, tensile, thermal and barrier properties, food safety and biodegradability rates. These results have been used to design the most appropriated multilayer structure in terms of mechanical resistance, barrier requirements and food contact assessment. Finally TRAYSRENEW sheet and top-film have 3 layers (ABA), all of them made by biodegradable materials and fibre-PLA biocomposites.
4. Development of thermoformed trays and upscale
Thermoforming steps are crucial to determine the final packaging properties, mainly mechanical and barrier properties. Thermoforming is the process of forming a thermoplastic sheet into a three dimensional shape (or a tray).
To obtain good thermoformed trays, as example, there are some parameters which have to be controlled such as:
1- Type of material and its behavior: In our case biodegradable semi-crystalline polymers such as PLA and its biocomposites. It is very important to control polymer thermal properties, which are one of the most relevant critical aspects of the process. PLA has lower Tg and softening temperature than PET or PS and also an intrinsic thermal conductivity lower than polystyrene and PET. These factors, for example indicate that the cooling time in the mould will be greater for PLA than either PS or PET. Fillers and fibres increase polymer stiffness but usually not polymer transition temperatures, however, do affect the thermal properties of the sheet. Therefore, these parameters have been adjusted for each web structure evaluated within the project.
2- Type of thermoforming process: vacuum-forming, pressure-forming and plug assisted thermoforming. The type of thermoforming used has different material conditions requirements that could be optimized in each processing step: Also, there are materials that couldn´t be used for specific thermoformed processes. In TRAYSRENEW project a vacuum-thermoformed process was used.
3- Type of mould: male, female, matched moulds. Depending of the mould type different adjust in the materials could be performed. In TRAYSRENEW a male or positive mould.
To obtain TRAYSRENEW final thermoformed trays, all these conditions have been evaluated and processing parameters such as time, temperature, pressure and speed have been optimized. A specific mould has been designed considering tray format used at the company “Productos Florida” being able to use at their facilities.
All thermoformed trays have been characterized, analyzing different properties such as:
- Wall thickness distribution:
- Optical microscopy evaluation
- Sealability test
- Mechanical properties (compression)
- Thermal properties
- Oxygen and water vapour transmission rate
Poultry shelf-life study in the new developed trays
The shelf-life of meat packaged using modified atmosphere packaging (MAP) depends on gas concentrations, and other factors, including storage temperature, initial contamination degree, materials permeability to gases (oxygen, carbon dioxide, water), and the headspace volume in the packaging. Freshness and shelf-life are affected by the inherent properties of the product just as much as by external factors such as the type and quantity of microorganism, water activity raw, pH value and so on....
The final result of TRAYSRENEW project is a fully evaluation of poultry shelf-life by using the developed packaging. To decide the final packaging system four different systems have been evaluated, using two different types of trays and top-lids. Chicken breast was packaged in the facilities of Productos Florida, located in Almassora (Valencia, Spain) using a fully automated tray sealing unit. During the trials, several machine parameters such as, temperature and time of sealing parameters time and web tension have been adequate to the new packaging materials; all necessary poultry trials samples have been obtained and tested.
Shelf-life evaluation
During spoilage, different metabolites are released from the product due to both microbial and enzymatic spoilage. The point of spoilage is usually defined as the maximum acceptable bacterial level and/or when meat reaches an unacceptable odour/flavour or appearance for consumption. However the most common indicators of spoilage are off odour, discoloration and production of gases.
To identify the first signs of meat alteration, different indicators were proposed for consideration, most important being headspace, pH, lipids oxidation products, colour, and microbiological counts. The evaluation was very satisfactory, headspace gas evaluation and pH tests showed correct parameters until 10 days.
An excessive oxidation of muscle lipids can produce compounds that adversely affect the quality of meat. These compounds are in some cases associated to off-flavours and off-odours, loss of colour, vitamins, lower consumer acceptability and also affect the safety of meat. To measure the oxidation degradation process two different techniques were used: TBA and Hexanal parameters analysis. Both results indicate that all combination of trays and lids get over 7 days and one of them could be arrive until 9-10 days.
Microbiological evaluation
Microbial contamination of the muscles starts at the point of slaughter. Contamination from the external surface of the carcass, internal gastrointestinal tracts, faeces and from the environment such as the slaughterhouse and equipment used for slaughtering can determine the initial composition and load of spoilage microorganism on the meat.
The spoilage of raw poultry is mainly caused by microbial growth, aerobic spoilage bacteria are very effectively inhibited by CO2 in MAP and refrigerated storage. Three main microorganism tests were evaluated; Enterobacteriaceae that is a large group of bacteria involving many foodborne pathogens, including pathogenic Escherichia coli, Shigella, Salmonella, Yersinia and many others. E. coli and total aerobic Mesophyll (TAM) which is a big group of bacteria able to grow at warms temperature (between 20 and 45ºC), and they include bacterium of different families without other relationship than temperature. All combinations show good behavior until 8 days.
Sensory evaluation
Finally, the sensory evaluation of the chicken breast was performed by evaluating the odor and the appearance of this product. Trained personnel were used for sensory analysis. Chicken breasts were evaluated using a pass-no pass criteria. The properties used in the evaluations were total intensity of the odor, appearance and drip. All samples passed the sensory analysis, although the evaluated packaging solution is an experimental design that could be implemented to avoid for example the formation of exudates in the bottom of the tray, which was the only negative aspect.
Summarizing the entire obtained results TRAYSRENEW consortium is satisfied and the main objectives have been accomplished during the project, nonetheless, some improvements in the upscale of fibres, optimized of up scaling materials processing processes and finally in the packaging system design will be implemented in further projects.
Project Results:
Poultry sector it has gained importance and its market has been the most dynamic in the last decade increasing its production each year since 1999. Medium terms prospects remain positive with an increased consumption of poultry and pigmeat compared with other meals. Globally, the projected consumption and production would increase from 98 million t in 2009 to 120 million t in 2017 especially in the developing countries where growing incomes increase the demand for meat (82% of the projected global growth) according to FAO.
Bioplastics market is being promoted during the last years due to numerous causes such as the increasing of crude oil price and its variability, the eco-friendly awareness of consumers, producers and transformers and so on. Thus, it is increasing the demand and the pressing for the plastic industry branch (worth EUR 200 billion in all sectors of Europe) to use alternative raw materials. Currently, available bioplastics types cover approx. 5-10% of the plastics market. Bioplastics development is just beginning and their market share is well under one-three percent (consumption estimated by the Association: approx. 50 000t in Europe). The market is growing and in many application areas such as packaging, the quantity of the demand and the number of bioplastics types and alternatives is increasing dramatically.
In addition, the price of bioplastics has continued to fall over the past ten years. Their competitiveness over conventional plastics should also continue to improve into the future through more effective processes, possible economies of scale and simultaneous increasing competition from new market players. New bioplastics grades have been developed presenting better properties and more functionalities than older grades. So the annual growth is considerably higher than 20%.
The economic impact of each SME after the development of TRAYSRENEW project is been estimated as positive. First’s considerations were based in the amount of consumed poultry and the expected increase, following by the specific amount of this poultry that is packaged, aprox: 3.542.223.000 kg by 2016. With this conservative estimation the number of packaging that will be sold at 2016 is around 17.712.000.000 units, with only a market quote of 0.5% in 2014 and 2% in 2016 the estimated number of packaging units that will be sold in 2016 will be around 662 million. Despite of TRAYSRENEW solution is more expensive than conventional packaging materials solutions the forecast will be positive, and besides this solution is cheaper than 100% bioplastics packaging solutions.
Considering that the application will mature through the years, we expect to absorb the benefits of economies of scale in order to reduce the cost further. Moreover, the cost of hydrocarbons as a raw material is likely to increase and, as a consequence, prices of conventional plastics too. This way, we expect to reduce the prices difference existing between plastics coming from petroleum based materials and our solution. And also, this application will be implemented in order to be suitable for other food products.
So, the consortium believes that there is potentially a very large economic benefit to Europe and the SME consortium members. The assumptions which have been made for predicting the future market of the final product have been done taking into account the external influences. These external influences include compliance with regulations, market place credibility and competition. We have evaluated these risks and evaluated their commercial impact on the project, all the defined risk have been overcome by the expertise and knowledge of the research centers involved in the project (ITENE, EHU and MATRI) and the widely know-how and professionalism of each SME of the consortium (Termoformas Levante, Rodenburg Biopolymers, Rondol technology, Gaviplas, Artic Fiber and La Florida).
Regarding exploitation results all the IPR results have been managed by the consortium including two different types of patentable technology and tray design.
Several dissemination activities have been carried out such two strategic conferences organized by TRAYSRENEW members, the participation in trade fairs and conferences related to packaging (for example, HISPACK, INTERPACK, IAPRI) and other publications such as a project brochure, several press release, posters and other publications in scientific journals, in addition the project webpage have been used as a platform to share all the public information.
Potential Impact:
Poultry sector it has gained importance and its market has been the most dynamic in the last decade increasing its production each year since 1999. Medium terms prospects remain positive with an increased consumption of poultry and pigmeat compared with other meals. Globally, the projected consumption and production would increase from 98 million t in 2009 to 120 million t in 2017 especially in the developing countries where growing incomes increase the demand for meat (82% of the projected global growth) according to FAO.
Bioplastics market is being promoted during the last years due to numerous causes such as the increasing of crude oil price and its variability, the eco-friendly awareness of consumers, producers and transformers and so on. Thus, it is increasing the demand and the pressing for the plastic industry branch (worth EUR 200 billion in all sectors of Europe) to use alternative raw materials. Currently, available bioplastics types cover approx. 5-10% of the plastics market. Bioplastics development is just beginning and their market share is well under one-three percent (consumption estimated by the Association: approx. 50 000t in Europe). The market is growing and in many application areas such as packaging, the quantity of the demand and the number of bioplastics types and alternatives is increasing dramatically.
In addition, the price of bioplastics has continued to fall over the past ten years. Their competitiveness over conventional plastics should also continue to improve into the future through more effective processes, possible economies of scale and simultaneous increasing competition from new market players. New bioplastics grades have been developed presenting better properties and more functionalities than older grades. So the annual growth is considerably higher than 20%.
The economic impact of each SME after the development of TRAYSRENEW project is been estimated as positive. First’s considerations were based in the amount of consumed poultry and the expected increase, following by the specific amount of this poultry that is packaged, aprox: 3.542.223.000 kg by 2016. With this conservative estimation the number of packaging that will be sold at 2016 is around 17.712.000.000 units, with only a market quote of 0.5% in 2014 and 2% in 2016 the estimated number of packaging units that will be sold in 2016 will be around 662 million. Despite of TRAYSRENEW solution is more expensive than conventional packaging materials solutions the forecast will be positive, and besides this solution is cheaper than 100% bioplastics packaging solutions.
Considering that the application will mature through the years, we expect to absorb the benefits of economies of scale in order to reduce the cost further. Moreover, the cost of hydrocarbons as a raw material is likely to increase and, as a consequence, prices of conventional plastics too. This way, we expect to reduce the prices difference existing between plastics coming from petroleum based materials and our solution. And also, this application will be implemented in order to be suitable for other food products.
So, the consortium believes that there is potentially a very large economic benefit to Europe and the SME consortium members. The assumptions which have been made for predicting the future market of the final product have been done taking into account the external influences. These external influences include compliance with regulations, market place credibility and competition. We have evaluated these risks and evaluated their commercial impact on the project, all the defined risk have been overcome by the expertise and knowledge of the research centers involved in the project (ITENE, EHU and MATRI) and the widely know-how and professionalism of each SME of the consortium (Termoformas Levante, Rodenburg Biopolymers, Rondol technology, Gaviplas, Artic Fiber and Productos Florida).
Regarding exploitation results all the IPR results have been managed by the consortium including two different types of patentable technology and tray design. Several dissemination activities have been carried out; one strategic conferences organized by TRAYSRENEW members, and project brochure, several press release, posters and other publications in scientific journals, in addition the project webpage have been used as a platform to share all the public information.
List of Websites:
www.traysrenew.eu