Promising scientific discovery to extend the shelf life of strawberries

Monique Lacroix, a professor at the National Institute of Scientific Research (INRS), Quebec, Canada, and her team have developed a bioactive packaging film that can extend the shelf life of strawberries for up to twelve days. 

This packaging film is made of chitosan, a natural molecule discovered in shellfish shells. Chitosan possesses key antifungal properties that restrain mould growth. The film also contains nanoparticles and essential oils which have antimicrobial properties.

According to Lacroix, essential oil vapours protect strawberries. In case if the film interacts with strawberries, the nanoparticles and chitosan prevent mould and pathogens from reaching the surface of the berry.

The formula created for this packaging film is effective against various types of pathogens. The film has been tested on 4 microbial cultures. Lacroix stated that during the testing the film proved its effectiveness against Aspergillus niger, a highly resistant mould that leads to substantial losses during strawberry production.

It also showed antimicrobial efficacy against Listeria monocytogenes, Salmonella Typhimurium, and Escherichia coli,  which come from contamination during food handling.

The scientists also combined the packaging film with an irradiation process. When film was exposed to radiation, there was noted longer shelf life, lowering the level of loss twice compared to the control (without film or irradiation). On day 12, the team noted a 55 % loss rate for the control group of strawberries, 38 % for the group with the film, and 25 % when irradiation was applied.

Besides, after the irradiation, the level of polyphenols, molecules which give strawberries their colour and have antioxidant properties, was preserved or increased.

At present, the cost of this new bioactive film technology has not been evaluated. "I would be delighted to work with an industrialist who makes packaging films," said Monique Lacroix.