Edible packaging from legume by-products

Abstract

The world plastic industry produces over 322 million tons of waste per year. Thus, bioplastic and edible packaging are highly researched due to their reduced environmental impact. Legumes have been used in packaging in the form of soy fibre and protein. Soy fibre is extracted by sieves, columns or freeze-drying sieving, then processed physically by compression molding or enzymatically by microbial transglutaminase. Soy proteins are extracted by centrifugation or filtration/ultrafiltration. Protein manufacturing can be achieved by addition of several ingredients: plasticizers, surfactants, biodegradable polymers and oils. Alternatively, proteins can be modified via chemical cross-linking (salts), radiation modification (UV), enzyme cross-linking or surface modification. Legume wastewater contains interesting levels of carbohydrates, with as much as 2.5 g/100 g of insoluble fibre. In addition, proteins account for up to 1.6 g/100 g. Therefore, a new technology that upcycles fibre and protein from legume wastewater into edible packaging is encouraged. The challenge is achieving acceptable structure and thermal stability while keeping the costs low. Processing legume fibre and proteins can provide the desired technological quality. In addition, upcycling by-products such as wastewater can reduce manufacturing costs. This could be the start of a new era for bioplastics and sustainable food packaging.