In order to provide sustainable food solutions, scientists from the NTU-Harvard T. H. Chan School of Public Health Initiative for Sustainable Nanotechnology (NTU-Harvard SusNano) have developed a biodegradable food packaging material that can eliminate harmful bacteria. Researchers from Nanyang Technological University, Singapore and Harvard T.H. Chan School of Public Health have collaborated on this new technology, which is also water-proof and able to extend shelf-life of fresh fruit by up to 3 days.

Zein is the main component of this innovation, which is a corn protein produced from corn gluten meal. It’s also a waste by-product from using corn starch or oils to produce ethanol. Other raw materials used are naturally derived biopolymers and antimicrobial compounds. For the latter, these include thyme oil and citric acid. The product is then manufactured by electrospinning the materials with cellulose, a polymer starch found in plant cell walls, and acetic acid.

When in use, the item releases the antimicrobial compounds when it’s exposed to an environment with increased humidity and containing harmful bacteria like E.coli and Listeria. The compounds prevent bacterial growth on the surface of the packaging and food item itself, lasting for months and even after several exposures.

In experiments, the researchers enclosed strawberries within the product. They found out that the fruit stayed fresh for 7 days before mould started to develop, longer than the typical 4 days.

Professor Mary Chan, Director of NTU’s Centre of Antimicrobial Bioengineering, who co-led the project, said: “This invention would serve as a better option for packaging in the food industry, as it has demonstrated superior antimicrobial qualities in combatting a myriad of food-related bacteria and fungi that could be harmful to humans. The packaging can be applied to various produces such as fish, meat, vegetables, and fruits. The smart release of antimicrobials only when bacteria or high humidity is present, provides protection only when needed thus minimising the use of chemicals and preserving the natural composition of foods packaged.”

Professor Philip Demokritou, Adjunct Professor of Environmental Health at Harvard Chan School, who is also Director of Nanotechnology and Nanotoxicology Center and Co-director of NTU-Harvard Initiative on Sustainable Nanotechnology, who co-led the study, said: “Food safety and waste have become a major societal challenge of our times with immense public health and economic impact which compromises food security. One of the most efficient ways to enhance food safety and reduce spoilage and waste is to develop efficient biodegradable non-toxic food packaging materials. In this study, we used nature-derived compounds including biopolymers, non-toxic solvents, and nature-inspired antimicrobials and develop scalable systems to synthesise smart antimicrobial materials which can be used not only to enhance food safety and quality but also to eliminate the harm to the environment and health and reduce the use of non-biodegradable plastics at global level and promote sustainable agri-food systems.”

Food packaging accounts for bulk of plastic waste, and in Singapore in particular, it is a major source of trash in the country. Out of 1.76 million tonnes of waste produced, 1/3 comprised of packaging and about 55% were made out of plastic.