The effect of whey protein edible coating on microbial quality of rainbow trout fillet during cold storage

Whey protein based edible coating containing 0. 5، 1 and 1. 5% (w/v) thyme essential oil was used for inhibition of bacterial growth of rainbow trout fillets during cold storage. Microbial analyzes (total viable counts، psychrophilic counts، lactic acid bacteria and Enterobacteriaceaeas) as well as total volatile basic-nitrogen (TVB-N) and pH measuring were performed periodically every four days. Results showed that whey protein coating containing thyme essential oil was able to inhibition of bacterial growth of fish fillets. Also the TVB-N and pH values in the coated samples were significantly (p<0. 05) lower than those of non-coated treatment. Among the treatments used in this study، treatment with 1. 5% thyme essential oil containing edible coating was the most effective treatment against evaluated bacteria in this study. As could extend the shelf-life of rainbow trout fillets stored at refrigerator for at least 4 days compared to control.