Canadian researchers extend strawberry shelf life with shellfish-based film developed with radiation tech

17 Jun 2021 --- Researchers at the Institut national de la recherche scientifique (INRS), Canada, have developed a packaging film capable of keeping strawberries fresh for up to twelve days.

Made of chitosan, a natural molecule found in shellfish shells, the film is a food industry by-product containing key antifungal properties that curb mold growth. 

The packaging film also contains essential oils and nanoparticles, both of which possess antimicrobial properties.

Published in Food Hydrocolloids journal online, the study shows the packaging film could protect against microbes Escherichia coli, Listeria monocytogenes, Salmonella Typhimurium, and Aspergillus niger. 

Monique Lacroix, the lead researcher on the project, states: “Essential oil vapors protect strawberries. And if the film comes into contact with strawberries, the chitosan and nanoparticles prevent mold and pathogens from reaching the fruit’s surface.”

Irradiation on strawberries
Lacroix and her team combined the packaging film with an irradiation process. During trials, the packaging film was exposed to radiation, through which team members noted a longer shelf life. 

The enhanced preservation cut the level of lost produce in half when compared to a control group of strawberries (without film or irradiation). Strawberry shelf life increased by more than half when packaged in the shell-based film.

On day 12, the team recorded a 55 percent loss rate for the control group of strawberries, 38 percent for the group with the film, and 25 percent when irradiation was added.

“Irradiation not only extended shelf life, but it also helped preserve or increase the number of polyphenols in the strawberries. These molecules give strawberries their color and have antioxidant properties,” assert the researchers. 

Antimicrobial tech fights food waste 
Lacroix and her teams’ development comes as antimicrobial technology is increasingly identified as a solution to food waste. 

The COVID-19 pandemic has further cemented consumer concerns over food safety and protection against the spread of bacteria and viruses. 

The EU-funded NanoPack project is similarly creating antimicrobial films based on the combination of natural nanomaterials and essential oils.

The technology has proven capable of extending bread shelf life by at least three weeks, fresh cherries by 40 percent and yellow cheese by 50 percent. NanoPack is preparing the technology for commercial launch.

Other food waste fighting technologies are also proliferating in answer to increased home food delivery demands during the pandemic. For example, food waste prevention specialist SavrPak began piloting its patented packaging technology this year after winning a P&G Ventures Innovation Challenge and was awarded US$10,000 to fund its expansion. 

The company created a chemical-free, food-grade material and a peel and stick patch, which traps moisture away from stored food to prevent it from going soggy and spoiling. 

Edited  

By Louis Gore-Langton