Edible coating preserves fish fillet

22 Sep 2016. NUS food scientists have developed an edible coating which can preserve the quality of chilled fish fillets.

Fish fillet and other seafood gets spoilt easily during storage and transportation. This causes economic loss for the food industry. These products also have a limited shelf-life. A team led by Prof YANG Hongshun from the Food Science & Technology Programme at the Department of Chemistry, NUS has developed an edible coating which can preserve the quality and reduce the deterioration of chilled fish fillet. The research team, which includes Ph.D. student Miss FENG Xiao found that by applying a coating made of chitosan with gelatin, they can extend the shelf-life of chilled fish fillet.

Chitosan is a polysaccharide that is obtained from the hard outer skeleton of shellfish, including crabs, lobsters, and shrimp. The chitosan/ gelatin coating was found to significantly prevent the deterioration of fish fillet when it is kept refrigerated at 4 ºC. In their experiments, the team discovered that a combination of chitosan with 7.2% gelatin has optimal effect on preserving fish fillet quality when it is kept for 17 days in cold storage. This coating also showed significant antimicrobial effects, which suppressed the growth of microbes.

The chitosan with 7.2% gelatin coating could be a way to reduce the spoilage of chilled fish fillet and seafood products. Also, fish gelatin is extracted from fish skins and bones, of which 1,500 tonnes are produced annually in Singapore. Utilising fish gelatin in the processing of fish and seafood products can reduce fish processing waste, which contributes to environmental pollution.

This research gives deeper insights into the nanostructural changes in fish fillet to elucidate the mechanism of fish deterioration in cold storage conditions. The research team plans to explore the use of the chitosan/ gelatin coating on shrimp and other seafood products in the future.

Figure shows (a) coating treatments on fish fillet; (b) atomic force microscopy (AFM) image of the degradation of fish muscle protein after nine days of cold storage. The fish fillet which was treated with the “chitosan with 7.2% gelatin” coating remained in a better condition compared with the control samples which did not receive any treatment.

References

Feng X., Bansal N., & Yang H. “Fish gelatin combined with chitosan coating inhibits myofibril degradation of golden pomfret (Trachinotus blochii) fillet during cold storage”. Food Chemistry (2016), 200, 283-292.

Sow L.C., & Yang H. “Effects of salt and sugar addition on the physicochemical properties and nanostructure of fish gelatin”. Food Hydrocolloids (2015), 45, 72–82.