The effect of the commercial fish gelatin protein hydrolysate on rainbow trout (Oncorhynchus mykiss) fillet quality

Abstract Willing to increase the shelf life of the food matrix, studies regarding new preservations methods are developed to preserve fish deterioration. The application of natural additives as preservatives is increasingly common, with a current emphasis on the growing use of protein hydrolysates, in substitution to artificial ones. These compounds have been the subject of recent studies, focusing on determining their functional properties and the best form of applying peptide chains. The present study aimed to evaluate the effects of the protein hydrolysate obtained by the enzymatic hydrolysis of commercial fish gelatin added to rainbow trout fillets (Oncorhynchus mykiss) packed under vacuum and maintained under refrigeration. The fillets were distributed into three sample groups (controls and hydrolysate addition at 1:10 and 1:1 ratios). Microbiological and physico-chemical assessments were carried out. The results were compared and correlations observed regarding fish preservation assessments. A relationship between pH, redox potential and N-TVB was verified when compared to microbial development, especially with regard to psychrotrophic aerobic heterotrophic bacteria count. It was concluded that the application of protein hydrolysate as an additive is promising and can be effective in the control of food quality and maintenance of freshness for a longer period.