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NEW MATERIALS

Green packaging

Fruits and vegetables are raw material for edible plastics that protect food

Guava alongside edible plastic made with substances extracted from the fruit’s pulp and rind

Léo RamosGuava alongside edible plastic made with substances extracted from the fruit’s pulp and rindLéo Ramos

An imagined future with edible plastic packaging that can be incorporated into soups and juices without ill health effects is not a far cry from reality. New possibilities for food storage that avoid post-consumption packaging waste and also add nutrients to consumers’ diets are being developed experimentally in laboratories at universities and research centers. The Brazilian Agricultural Research Corporation (Embrapa) is studying new materials that can be turned into packaging or even food ingredients. These bioplastics or biopolymers, as researchers call them, can also be incorporated into biodegradable packaging. “These materials have the nutritional properties, flavor and color of produce, or they can be transparent, filmy, and look like ordinary plastics,” explains Luiz Henrique Capparelli Mattoso, a researcher at Embrapa’s Agricultural Instrumentation Division in São Carlos, state of São Paulo.

These bioplastics are made from fresh foods or from wastes derived from juice-making or other industrial processes. Compounds such as polysaccharides, considered to be natural polymers, are extracted from these raw materials. Like the plastics produced from petroleum byproducts, they are made of macromolecules of long-chain carbohydrates. Most biopolymers are also biodegradable, so packaging materials not intended to be brought to the table can decompose naturally in the garbage in a few days or weeks. Mattoso, who has studied these materials for the past 20 years, sees degradable and edible bioplastics as an answer to the environmental impact caused by synthetic plastic. “Reducing the amount of synthetic plastic packaging in dumps and landfills is a necessity,” he says. The new materials offer the same versatility as traditional plastics, opening up an unlimited range of uses and possible formulations for packaging and functional foods.

The edible plastics being developed by Mattoso’s group were first created eight years ago in connection with the Network of Nanotechnology Applied to Agribusiness (AgroNano). The members of the network are researchers from companies and a number of research institutions, and include Professor Márcia Aouada of São Paulo State University (Unesp) in Ilha Solteira, researcher Henriette Monteiro Cordeiro de Azeredo of Embrapa’s Tropical Agroindustry Division in Fortaleza, state of Ceará, and Tara McHugh of the Agricultural Research Service, United States Department of Agriculture. The plastic films are basically made from certain types of polysaccharides such as starch, pectin and hydroxypropyl methylcellulose. These components are extracted, for example, from the pulp and rind of fruits such as guava, papaya, passion fruit, banana, açaí, kiwi and peach, or from legumes such as beets and carrots. The applications are numerous. Edible or biodegradable, they could be used to wrap several types of food, including animal feed.

Bioplastic made from açaí and nanoparticles of chitosan, a substance that has a bactericidal effect

Léo RamosBioplastic made from açaí and nanoparticles of chitosan, a substance that has a bactericidal effectLéo Ramos

One as-yet-unresolved issue is the potential risk that the biopolymer could attract animals while in storage or on supermarket shelves. “We don’t know if it would attract mice or cockroaches. We haven’t done any specific testing, but we haven’t ever had that problem in all the years of our research,” Mattoso says. Any potential contamination of the packaging by bacteria or other impurities could be resolved, the researcher says, by adding substances such as chitosan, cinnamon or propolis, which has a bactericidal effect. “Another solution would be to use an outer packaging material that is biodegradable but not edible, to package some foods consumed in natura,” he explains. Biopolymers can be washed with non-soapy water.

“American colleagues, such as Tara McHugh, are now working with edible films that could be used in Japanese restaurants,” he notes. “Some customers are allergic to the algae used to wrap a type of sushi. The films can be used as a substitute, without any loss of flavor or food quality.” The researcher lets his imagination fly on the new possibilities that biopolymers bring to the food industry. “It’s possible to produce plastics with the flavor of any seasoning and add it to food.” A chicken could be wrapped with a type of bioplastic containing molecules that would have the proper seasoning for the food. “When you put it in the oven, the water in the meat evaporates and solubilizes the film, breaking it up and seasoning the food as it cooks,” he explains. The advantage of seasoning-infused packaging is that it can be used as food rather than be discarded. Some packaging materials could also be liquefied in a blender to make juices. “It is possible to work with new food concepts,” Mattoso says. His research on edible plastics in São Carlos over the past eight years has received R$200,000 in funding from Embrapa, the National Council for Scientific and Technological Development (CNPq) and FAPESP.

Pomegranate ravioli
In Fortaleza, Azeredo developed an edible plastic from pectin, pomegranate juice, citric acid and glycerol, a substance that can be a byproduct of vegetable oil processing. “It has good mechanical properties, and the color and taste of pomegranate,” she explains. “We created the product so it could be ingested with food.” According to Azeredo, the idea of developing the film came up in 2014, when she spent time as a visiting researcher in Norwich, England, through the Embrapa Labex program, which promotes scientific cooperation with institutions in other countries. “Pomegranate is greatly enjoyed and consumed in England, and I knew it had market appeal because of the health benefits conferred by its alleged antioxidant properties,” she explains. “I thought it would be interesting to make use of the attractive color of the fruit pulp to incorporate it into a biopolymer.” The research was conducted in 2014, but Azeredo has been working with edible and biodegradable plastics since 2007.

Edible plastics developed at Embrapa

Léo RamosEdible plastics developed at EmbrapaLéo Ramos

On the subject of applications, Azeredo says that the film developed in England, like similar ones created by Mattoso, could also be used by restaurants to wrap sushi, or to make appetizer pastries or transparent raviolis—small meat-filled pockets, for consumption or even for decorative effect at meals. “The product could also be marketed in powder form, and then dissolved in water as a coating for fruit,” he explains. “For this application, the bioplastics would be immersed in liquid, removed and then dried to form a film.” According to Azeredo, the dried film would act as a protective barrier—a kind of thin skin that would reduce permeability to gases and moisture—and help increase food stability.

Another possible application is the production of fruit ribbons in the vein of Fruit by the Foot, a snack sold in the United States, that would take the form of gummy strips rolled up and packaged like adhesive tape. They are bioplastics made of fruit with added vitamins. “In the United States there is a company that makes films from the pulp of various fruits and vegetables and sells them to consumers for preparing sushi rolls or wraps in several flavors.”

Developing a film that prevents oxidation in cut-up fruit is the goal of the research group led by Professor Florencia Cecília Menegalli of the School of Food Engineering at the University of Campinas (Unicamp). She and her doctoral student Tanara Sartori use starch from green plantains as a raw material for films that preserve cut-up fruit. To this material they added lipid microparticles (a mixture of fatty acids) containing vitamin C, an antioxidant. “Earlier we had used banana starch to develop biodegradable packaging. Now we’ve opted for a packaging material activated by adding the antioxidant to the formula,” Sartori explains. First, they needed to encapsulate those substances in order to incorporate them into the film. “Encapsulating the antioxidant in the microparticles is important for maintaining controlled release of the substance during storage, to preserve the product before it reaches the end consumer.”

Production phase of edible plastic made from strawberries, for use in packaging

Léo RamosProduction phase of edible plastic made from strawberries, for use in packagingLéo Ramos

Microparticles are also used in the coating, a viscous liquid in which the fruit to be protected must be immersed. They are immediately removed to be dried for several minutes, and a protective film then forms over the fruit pieces. According to Sartori, research findings not yet published point to a preservative effect on the color of apples, even when cut in half, when coated with film having antioxidant properties.

The steps needed to bring these products to market will depend on a number of factors. In the past decade, Henriette Azeredo of Embrapa developed a film based on mango pulp, to which were added cellulose nanofibers obtained from cotton fiber (see Pesquisa FAPESP Issue nº 176), but it didn’t generate any patents or a commercial product. “At the time, several companies contacted me, but none was interested in bringing the technology to market,” she says. “The films have not yet been produced on an industrial scale. There were no scale-up studies, so their cost is only an estimate and is thought to be high. For that reason, it’s hard for them to compete with synthetic plastics,” comments Professor Paulo Sobral of the School of Animal Science and Food Engineering at the University of São Paulo (USP), Pirassununga campus. “The use of processing waste could reduce the end price of the bioplastic, but the figure is very hard to quantify because it depends on the formulation, scale and type of biopolymer,” Mattoso says.

The research projects conducted by the three groups have generated recent papers published in scientific journals. The films that are closest to becoming commercial products are the ones created by Mattoso. “We’ve already done the proof of concept, and developed several packaging formulations and a pilot-scale production process,” he says. So far, seven companies interested in the edible films have contacted Embrapa. “We’re in negotiations with some of them. As soon as we come to terms with a company and sign a partnership agreement, we’ll start adjusting the formulation and develop the final product,” Mattoso says.

Project
Study and optimization of natural fiber-reinforced edible polymer biocomposites formulated with fruit and vegetable processing wastes (nº 2014/23098-9); Grant Mechanism Scholarships in Brazil – Regular – Fast-track Doctorate; Recipient Caio Gomide Otoni (Embrapa); Principal Investigator Luiz Henrique Capparelli Mattoso (Embrapa); Investment R$92,264.64.

Scientific articles
SARTORI, T. et al. Development and characterization of unripe banana starch films incorporated with solid lipid microparticles containing ascorbic acid. Food Hydrocolloids. V. 55, p. 210-19. April 2016.
AZEREDO, H. M. C. et al. Development of pectin films with pomegranate juice and citric acid. Food Chemistry. V. 198, p. 101-6. May 2016.

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