Investigation of flesh quality and shelf life at different storage conditions of European sea bass, Dicentrarchus labrax, fed with diets included natural and synthetic additives

This study was carried out to examine the shelf life and fillet quality of sea bass fed with diets which are included grape seed extract (GSE) and Vitamin E. In the study, fish were fed with 4 experimental diets (Control, GSE, Vitamin E and mixture of GSE - Vitamin E) for 18 weeks. There were no significant differences observed between the growth parameters of fish fed with experimental diets (P>0.05). In the feeding trail in order to evaluate the relationship between the experimental diets and the growth performance of fish economically, economic conversion and economic profitability ratios were calculated due to reveal the most cost-effective and proper diet used in this trial. After the feeding trial, fish were harvested, stored at 4°C in ice and -18°C in freezer. Samples were taken at day 0,7, 14 and 21 for ice storage and once a month for frozen storage. In the storage trials, biochemical (crude protein, crude lipit, humidity and ash), chemical (TVB-N, TBA, pH, fatty acid profile) color change and microbiological analyses were performed. Results from analyses for ice storage indicated that fish were fed with GSE included diet the exceeded the upper limit for microbiological counts later than the others. The lowest TVB-N value was detected from GSE extract when the upper limit for microbiological count exceeded (14th day of storage). The consumable levels for TBA never exceeded throughout the storage period. However, there were increases observed for TBA when the upper limit for microbiological count exceeded (14th day of storage). For the color change, L* value of the groups showed increases entire storage periods. For the frozen storage, upper limits never exceeded in terms of chemical or microbiological analyses. Overall, GSE extract was overcoasting for culture conditions than the other diets, but in the storage trials better results were obtained from this diet group than the others. If the cost of GSE is decreased by %20, this additive would be effective for the aquaculture industry.