Researchers at São Paulo State University in Brazil have produced a new plastic material that as well as being biodegradable and anti-microbial, is also edible. The material, made from gelatin, clay and a nanoemulsion of black pepper essential oil, could find a range of uses in food packaging.
As reported in the journal Polymers [da S. Saranti et al. Polymers (2022) DOI: 10.3390/polym13244298], the material offers higher tensile strength than petroleum-based plastic, and could reduce the huge amount of environmental pollution from the disposal of food packaging. Over 350 million metric tons of plastic are produced globally every year, the majority ending up as rubbish in the world’s oceans. This plastic is mostly derived from non-renewables such as petroleum, driving research into biodegradable packaging materials to reduce the dependence on fossil fuels for plastic production.
Such packaging materials also have to be able to prevent contamination by microorganisms and extend the shelf life of products. Here, a bioplastic, also known as “green plastic”, was made from type B bovine gelatin, a cheap, abundant product sold in shops in the form of a colorless powder, and which offers useful film-forming properties. To improve its mechanical properties and vapor permeability, cloisite Na+ nanoclay was added to the gelatin to make the film more homogeneous and with better tensile strength than standard polyethylene packaging.
A nanoemulsion made from black pepper essential oil was also added to give the packaging a more attractive flavor and odor, as well as higher permeability and better thermal stability, while anti-microbial and anti-oxidant components in the polymeric matrix will help extend the shelf life of food products packaged with the material. As researcher Marcia Moura Aouada said, “If this kind of packaging becomes widespread in the marketplace, it could significantly reduce the use of plastic made from non-biodegradable polymers and hence the amount of solid waste. In addition, the bioplastic will better protect packaged food against contamination by pathogens and help reduce losses.”
The bioplastic was originally designed to package beef in the form of hamburgers, as they are at risk of microbial contamination and produce a strong smell, but the approach of adding nanoclay and essential oil nanoemulsion to a gelatin matrix could be extended to other foods, depending on the type and ratio of essential oil.
In addition to this environmentally friendly breakthrough, the team are making wound dressings from bacterial cellulose, and edible packaging containing nanostructures derived from kale purée, cocoa purée, cupuacu purée, camu extract and nanoemulsions, that could find uses in the food, pharmaceutical and cosmetics industries.
“If this kind of packaging becomes widespread in the marketplace, it could significantly reduce the use of plastic made from non-biodegradable polymers and hence the amount of solid waste."Marcia Moura Aouada