‘Smart’ food packaging keeps fruit fresh

The team, from Nanyang Technological University (NTU Singapore) and Harvard T.H. Chan School of Public Health, said its packaging material is biodegradable, sustainable and kills microbes that are harmful to humans. 

According to researchers, the material could extend shelf life by two to three days. The natural packaging is made from a type of corn protein called zein, starch and other naturally derived biopolymers infused with natural microbial compounds. These include oil from the common herb thyme, and citric acid which is commonly found in citrus fruits. 

NTU team develops energy saving glass

E-waste plastics get second life in the laboratory

Described in the journal ACS Applied Materials & Interfaces, the material was produced by electrospinning the zein and the antimicrobial compounds with cellulose, a natural polymer starch that makes up plant cell walls, and acetic acid which is commonly found in vinegar.

In lab experiments, when exposed to an increase in humidity or enzymes from harmful bacteria, the fibres in the packaging were shown to release the natural antimicrobial compounds. This killed common dangerous bacteria that contaminates food such as E. Coli and Listeria, as well as fungi.

The nature-inspired packaging is designed to release the necessary miniscule amounts of antimicrobial compounds only in response to the presence of additional humidity or bacteria, the team said. This ensures the packaging can endure several exposures and last for months.

Strawberries that were wrapped in the packaging during an experiment stayed fresh for seven days before developing mould, compared to counterparts in mainstream plastic boxes which only stayed fresh for four days.

Co-leader of the project, Professor Mary Chan, director of NTU’s Centre of Antimicrobial Bioengineering, said that the invention serves as a better option for packaging in the food industry due to its ‘superb’ antimicrobial qualities. 

“The packaging can be applied to various produces such as fish, meat, vegetables and fruits,” said Chan. “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, director of the Nanotechnology and Nanotoxicology Centre and co-director of the NTU-Harvard Initiative on Sustainable Nanotechnology co-led the study.

“Food safety and waste have become a major societal challenge of our times with immense public health and economic impact, which compromises food security,” Demokritou commented, adding that the team’s scalable material can be used not only to enhance food safety and quality but to reduce use of non-biodegradable plastics at global level, promoting sustainable agri-food systems.