Tecnalia develops legume protein-based films and coatings

By Tecnalia | January 28, 2016

Over the last two years, four European research centers (CNR-iPCF, SSICA, TECNALIA and POLIEKO) have been working alongside three business associations (CONSEBRO, PCS, ASSOCOMAPLAST) and five companies (IRIS, TEHNOS, RDX, TUBA and LAGRANA) linked to the foodstuff and plastics industries in order to find more sustainable and renewable sources for the plastics industry. Basically, the main aim of the European LEGUVAL project is to valorize the by-products of the legume processing industry, which are currently discarded, so that they can be used to prepare plastic materials for agriculture, packaging and automotive applications.

There is a growing urgency to develop novel products of natural origin and other innovative technologies that could help to reduce the widespread dependence on fossil fuels. Environmentally-friendly biocomposites made up of biofibres and bioplastics are new materials in the 21st century with a huge potential to solve environmental problems and the uncertainty in the supply of crude oil.

Thanks to their chemical and multifunctional properties, legumes provide society with various services such as: a source of products to feed humans and animals, fibres, biomass, biofuels and chemical products.

Leguval is setting out to valorize the co- and by-products of legumes by extracting their proteins and fiber so that they can be used as a raw material in developing packaging materials and bioplastics for agricultural use, and the remaining biomass as a source of biogas. The recovery of high-value compounds is a profitable way of making use of the by-products as most plant waste contains considerable quantities of potentially interesting compounds. Right now, coatings using pea proteins with very interesting barrier properties and composites with legume fibres have been obtained and which are due to be tested in real agricultural and packaging applications. Their application on an industrial scale will be taking place shortly. Furthermore, the remaining biomass has been found to be an excellent source of biogas, and that way the cycle for the use of the by-products would be fully completed.

The films/composites and coatings based on legume proteins would allow the packaging to be disposed of in composting plants or used to produce biogas. Similarly, in agricultural applications the plastics produced from proteins will be able to remain in the soil as a source of biodegradable nitrogen.

This project will be opening up various lines of research in the sphere of plant protein. In fact, the oxygen permeability properties of plastic films made of coated proteins have shown that the protein-based coating solutions display excellent barrier properties against oxygen and against relatively low or mid-range humidity on a par with the oxygen barrier properties of some synthetic plastic materials.

The co- and by-products of the processing industry for legumes such as peas, broad beans, lentils, etc. are being used as a raw material to develop plastic materials for packaging and agricultural applications. This strategy will provide the crops with added value through a novel use of the by-products which right now are only used as animal feed or fertilizers.

This aim is being achieved through the extracting of proteins to produce edible/biodegradable films. What is more, the biomass left behind in the extraction process is used as a filling in polymer composites to improve their mechanical properties, or as a power supply for producing biogas.

The ultimate aim is to make the materials developed competitive in the mid-term with respect to crude oil-based alternatives, above all bearing in mind the high price of some of the polymers produced from this raw material and the fall in the price of biodegradable polymers due to the increase in production in emerging countries such as India and China.