Effect of biodegradable films based on chitosan/polyvinyl alcohol/fish gelatin incorporated with cinnamaldehyde on shelf-life extension of rainbow trout (Oncorhynchus mykiss) fillets

The present study was conducted to compare the effect of adding cinamaldehyde in two forms i.e. free 1.6% v/v and nanoencapsulated 0.375% w/w on the properties of biodegradable film based on chitosan/polyvinyl alcohol/fish gelatin, and then it’s potential on shelf-life extension of chilled rainbow trout Oncorhynchus mykiss fillets at cold temperature. The results showed that the addition of free and nanoencapsulated cinnamaldehyde contributes to the increase of water vapor permeability WVP, as well as scanning electron microscopy SEM images revealed remarkable differences in the surface morphology between pure films and films containing free and encapsulated cinemaldehyde. In the second phase of the present study, the antioxidant/antimicrobial effects of the developed biodegradable films to increase the shelf-life of fish fillets in four treatments include Control i.e. without coating, samples coated with pure film i.e. without free and nanoencapsulated cinnamaldehyde CT; fillets coated with film containing 1.6% v/v free cinnamaldehyde FCCT; and the samples coated with a film containing 0.375% w/w nanoencapsulated cinnamaldehyde NCCT was investigated. Based on the results, the thiobarbituric acid levels in FCCT treatment were significantly lower than other treatments (p<0.05). The colorimetric test of fillets also showed that the luminosity index L* was lower than the other treatments from day 12 in FCCT treatment. The FCCT treatment showed also lower values of total viable TVC and psychrophilic bacteria PTC counts, reaching the maximum limit allowed for the human consumption only on the 12th day of storage. So, biodegradable films containing the cinnamaldehyde as a natural biopreservative might be used to extend the trout shelf-life.