From:Packaging News

Researchers at Tufts University in the US have come up with a substitute for plastic-based cling film using a protein found in silk.

The biomedical engineers have found a way to coat food with an almost invisible, odourless and tasteless layer of fibroin.

In a Scientific Reports paper, they described how fruit could be preserved for over a week using this new, environmentally-friendly, technique.

In tests, strawberries were left for seven days at room temperature and became discoloured and soft, but those coated with the silk protein appeared to stay juicy and firm. A similar result was achieved using bananas.

Explaining the science behind the material, the researchers said: “The regeneration of structural biopolymers into micelles or nanoparticles suspended in water has enabled the design of new materials with unique and compelling properties that can serve at the interface between the biotic and the abiotic worlds.”

“In this study, we leveraged silk fibroin quintessential properties (i.e. polymorphism, conformability and hydrophobicity) to design a water-based protein suspension that self-assembles on the surface of food upon dip coating.

“By using the dip coating of strawberries and bananas as proof of principle, we have shown that the formation of micrometre-thin silk fibroin membranes around the fruits helps the management of postharvest physiology of the fruits.

“Thus, silk fibroin coatings enhance fruits’ shelf life at room conditions by reducing cell respiration rate and water evaporation. The water-based processing and edible nature of silk fibroin makes this approach a promising alternative for food preservation with a naturally derived material.”