Scientists develop edible, biodegradable, anti-microbial plastic for food packaging
Food packaging is a major cause of environmental pollution globally. More than 350 million metric tons of plastic are produced every year – much of which ends up in our waterways. Of all the rubbish dumped in the oceans, 85% is plastic pollution. Plastic production also relies on the use of fossil fuels such as petroleum.
Given all these drawbacks, reducing the use of fossil fuels to produce plastic is the target of a great deal of research around the world. In the food packaging space, materials experts have focused on the development of biodegradable packaging materials that also prevent contamination by microorganisms and extend shelf life so as to reduce losses.
As part of this effort, a research team called the Composites and Hybrid Nanocomposites Group (GCNH) at São Paulo State University (UNESP) has produced a ‘green plastic’ that it hopes can offer a solution for the food industry.
The research, published in the journal Polymers, shows that the team have produced a bioplastic from type B bovine gelatin, an ingredient they say is easily found in retail stores in the form of a colourless powder.
“Gelatin was one of the first materials used in the production of biopolymers. It’s still widely used owing to its abundance, low cost and excellent film-forming properties,” said chemist and materials scientist Márcia Regina de Moura Aouada, a professor at the Ilha Solteira School of Engineering (FEIS-UNESP) and last author of the article.
“However, biopolymers for packaging have characteristics that need to be improved in order to be comparable to petroleum products, especially as far as mechanical properties and vapor permeability are concerned, so we added cloisite Na+ nanoclay to the gelatin,” she explained.
Improved strength and extended shelf life
Adding nanoclay made the film more homogeneous and increased its tensile strength to 70 megapascals (MPa). Conventional polyethylene packaging has less than half this tensile strength (in the range of 20 MPa-30 MPa).
“Besides nano clay, we also added a nano emulsion made from black pepper essential oil to give the packaging a more attractive flavour and odour. The mixture also extends the shelf life of food products packaged with the material, thanks to the inclusion of anti-microbial and anti-oxidant components in the polymeric matrix,” she said.
The bioplastic was originally designed to package beef hamburgers, which are vulnerable to microbial contamination and have a strong smell. However, the researchers said the principle of adding nanoclay and essential oil nanoemulsion to a gelatin matrix ‘can and will’ be extended to other foods, varying the type and proportion of essential oil used.
“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,” Moura Aouada said. “In addition, the bioplastic will better protect packaged food against contamination by pathogens and help reduce losses.”
The group also produces wound dressings from bacterial cellulose, and edible packaging containing nanostructures derived from kale purée, cocoa purée, cupuassu (Theobroma grandiflorum) purée, camu camu (Myrciaria dubia) extract and nanoemulsions, with potential applications in the food, pharmaceutical and cosmetics industries.
The research is supported by FAPESP via a Research Regular Grant and also via the Center for Development of Functional Materials (CDMF), a Research, Innovation and Dissemination Center (RIDC) hosted by the Federal University of São Carlos (UFSCar).
“Performance of gelatin films reinforced with cloisite Na+ and black pepper essential oil loaded nanoemulsion”
Authors: Fauze Aouada, Tascila Saranti (MSc), and Pamela Melo (Ph.D.) from UNESP; and Miguel Cerqueira, from International Iberian Nanotechnology Laboratory, Portugal.