By Kanishka Salwan, Head of Innovations (Pulp & Fibre), Yash Pakka
Agriculture-based industries generate a huge amount of waste from different agricultural activities. About one-third of the total food produced globally per year for consumption remains unconsumed and therefore gets wasted as stated by the Food and Agricultural Organisation (FAO). Food waste is one of the most difficult tasks the world is facing currently. Yet, just as any negative scenario can be turned into a positive with innovative endeavours, so too can this agri waste be put to good use. Let’s explore how the packaging industry can leverage this apparent waste.
Most food grain losses occur during the post-harvesting stage. The fruits and vegetables contribute to a significant amount of waste. As stated by the FAO, 20-30 per cent of fruits and vegetables are discarded as waste during post-harvest handling and processing operations. The agricultural waste consists of field residues such as stems, stalks, leaves, seedpods, and process residues like husks, seeds, roots, bagasse, molasses. Waste from food processing units consists of organic residues such as fruit seeds, citrus peels, potato peels, coconut shells, wheat straw, rice husks, pomace, etc. These wastes are usually discarded in landfills sites or used in preparing compost. Due to the varied composition of cellulose, hemicelluloses, proteins, lipids, these wastes serve as a raw material for the production of biodegradable and sustainable packaging material.
Biodegradable Packaging
Packaging waste adds to a major portion of solid waste and has raised environmental concerns over the years. The development of biodegradable packaging materials from natural residues such as agricultural residues is the need of the hour. The utilisation of agricultural waste is an economical and effective step taken for the development of sustainable and eco-friendly, biodegradable packaging materials. Using biodegradable packaging minimises waste and lessens the environmental consequences of using petro-chemical based synthetic packaging materials. Biodegradable films can easily disintegrate into the environment by natural factors such as microbes (bacteria, fungi, etc.) or abiotic components of the ecosystem thus having the least impact on the environment and ecosystem.
Starch, which is mainly extracted from cassava, potato peels, rice husk, wheat bran, is rich in amylose, exhibits thermoplastic properties that could be used in the development of packaging material. These can be easily obtained from agricultural waste at zero cost. Corn starch-based biocomposites added with rice husk and walnut shell were effective in enhancing the physical, mechanical, and thermal properties of biocomposites and could be of advantage as a sustainable packaging material.
Pectin, extracted from citrus peels and by-products of juice processing has diverse functionalities in sustainable packaging applications. It is the most pliable polysaccharide suitable for the formation of an effective biomaterial film due to its biodegradability, biocompatibility, and nontoxicity. Pectin films act as a good oxygen barrier and have decent hardness and adhesiveness properties.
Packaging films developed with coconut water and lime peel extract possessing antioxidant properties have shown the potential to extend the shelf-life of food products with an improved water barrier property and scale down the use of synthetic packaging material.
Among the plant proteins, soya-protein isolate is a fine alternative to develop new biobased packaging materials. Soya protein isolates (SPI) obtained from the soyabean oil processing industry have excellent gelling, emulsifying ability and strong water and oil holding capacity. SPI-based films usually show lower oxygen permeability as compared to films based on synthetic polymers, starch, hemicelluloses, and pectin.
Cellulose from agricultural waste such as rice straw, wheat hull, wood chips, wood pulp, maize stalk, sorghum waste, is used as raw material for the formation of biodegradable film packaging. It is the most abundant polysaccharide biopolymer available worldwide. Multiple hydroxyl groups of cellulose in cellulosic materials can be modified either partially or wholly by treating with numerous chemicals to produce a variety of end products stated as cellulose derivatives. Cellulose Nanocrystals (CNCs) and cellulose nanofibers (CNFs) are non-toxic, biodegradable, have high strength, and barrier protection. CNCs and Corn zein are utilised for the preparation of oxygen and water vapour barrier biocomposite films.
Plant cutin is the main element (80 per cent w/w) of the skin fraction of tomato pomace. Cutin extracted from tomato waste is a nontoxic, compostable, waterproof, UV-blocking, amorphous, insoluble, and infusible lipid-based polymer made of esterified C16 and C18 hydroxy acids.
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