Scientists at the Department of Food Science & Technology, Seoul Women’s University, proposed the idea as a way to make use of some of the byproducts of fish processing, thus minimising waste.
Edible biopolymer films could be created from the gelatine extracted from the trout skin using thermal protein denaturation conditions and plasticizer (glycerol) concentration as variables.
According to the study, published in the September issue of the Journal of Food Science, a 6.8% (w/w, wet basis) trout skin-extracted gelatin solution containing 9, 17, or 23% (w/w, dry basis) glycerol was heated at 80, 90, or 100 °C for 30, 45, or 60 min to prepare a film-forming solution.
The solution was then subjected to heating to form a stable matrix for a film. Heating at 90 °C for 30 min was suggested as the requirement for film formation.
As the concentration of glycerol in the film increased, film strength and moisture barrier properties decreased, while film stretchability increased.
The researchers concluded that trout skin by-products could be used as a natural protein source for fabricating biopolymer films stable at ambient conditions.
Significant amount of waste
“The fishing industry produces a significant amount of waste, including fish skin, due to fish processing,” state the scientists, led by Dayeon Kim.
“Trout skin waste has potential value as a protein source that can be used to form biopolymer edible films for packaging low and intermediate water activity food products, and thus may have practical applications in the food industry, which could be one way to cut waste disposal in the trout processing industry."
Title: Trout Skin Gelatin-Based Edible Film Development
Authors: Kim, D. and Min, S. C. (2012)
Source: Journal of Food Science, vol. 77, issue 9: pages E240–E246. doi: 10.1111/j.1750-3841.2012.02880.x