Recently, bioplastics have become increasingly interesting as an alternative to conventional plastics. For this reason, their manufacture using traditional technologies, such as extrusion, will help develop into an industrial scale. Gluten-free bioplastics are affordable, renewable, and as easy to process as regular plastic. Amid growing concerns about pollution and climate change, there is a growing demand for plastic substitutes that can be produced on an industrial scale. In a recent publication in the Journal of Cleaner Production, in an article entitled “Extrusion-treated Wheat Gluten-Based Bioplastics,” Jimenez-Rosado of the University of Seville and colleagues describe a new method for mass production of gluten-based bioplastics.
Bioplastic (Bioplastic) – a material produced from renewable sources of biomass, such as vegetable fats and oils, corn starch, straw, wood chips, sawdust, processed food waste. Bioplastics can be made from agricultural by-products, as well as from used plastic bottles and other containers using microorganisms. Conventional plastics, such as fossil fuels (also called gasoline polymers), are derived from petroleum or natural gas. By the way, not all bioplastics are biodegradable and do not decompose faster than plastics made from fossil fuels.
As a by-product in the bioethanol industry, wheat gluten is mainly used as animal feed, but is a very useful raw material. Not only is it widely available and relatively cheap, bioplastics made from it have mechanical and functional properties similar to those made from petrochemical products. Studies have shown that they would be especially useful as food packaging. “When it comes to the food industry – the area where plastics are used the most – these bioplastics are irreplaceable, because they are odorless and do not change the taste of food, ”says Jimenez-Rosado.
The next step is the industrial production of gluten plastic. Recent studies show that wheat gluten-based bioplastics may prove to be a practical and affordable replacement for conventional plastics. When making them, one of the most widely used methods is used – extrusion processing. “This is a very important point,” explains Jimenez-Rosado, “because in the manufacture of plastics, extrusion is accessible and familiar in production. ” Extrusion is a method of processing polymer materials by continuously pushing their melt through a forming head, the geometric shape of the output channel of which determines the profile of the resulting product or semi-finished product.
Compared to conventional polymers, bioplastics derived from gluten, structural changes occur at temperatures below ordinary, which makes it more elastic. Gluten-free bioplastics have a high alkaline pH and, during production, increase the ability to absorb water from the final material, and the addition of xanthan gum makes the bioplastic more rigid. The methods tested and developed in this study make it possible to obtain bioplastics from wheat gluten using well-known simple technologies.
Due to the costs and time spent on research and testing of new biodegradable and biodegradable polymers, bioplastics are at a disadvantage in comparison with petrochemical based plastics. Bioplastics make up less than one percent of all plastics produced in the world, and until recently, their production is on average 2-4 times more expensive than petrochemical plastics.
Obtaining wheat gluten bioplastics by extrusion was the main goal of the new study, modifying their structure by changing the pH value or by adding additives (glyoxal or xanthan gum). These bioplastics were characterized by measuring their mechanical properties and their ability to absorb water, which proves that modification of bioplastics causes changes in their properties. In addition, the tensile strength was increased at pH 9, probably due to increased binding under alkaline conditions. These results demonstrate the great potential of these materials to replace conventional plastics and plastics.