Effect of xanthan coating containing peppermint (Mentha piperita) essential oil on the chemical, microbial and sensory characteristics of Onchorhynchus mykiss at refrigerated temperature

Fish has high sensitivity to microbial and oxidative deterioration due to its high content of unsaturated fatty acids and proteins. Recently, natural and edible coatings have gained wide applications as alternative to synthetic preservatives to prevent fish from deterioration and quality loss. In this study, the effect of xanthan coating (0.5% w/v) containing peppermint essential oil (250, 500, 750, & 1000 ppm) on the quality of Onchorhynchus mykiss was evaluated at refrigerated temperature (4ºC) for a period of 20 days. Microbiological changes including, total viable count (TVC), psychrophilic bacteria (PTC), physicochemical changes including peroxide value (PV), thiobarbituric acid value (TBA), free fatty acid (FFA), pH, and sensory changes (taste, odour, texture, color & total acceptability) were evaluated periodically (at intervals of 5 days). Results indicated that the coating treatments could effectively retard the growth of bacteria as shown by less TVC and PTC compared to those of control (without any coating/preservative) during storage. The coating treatments also could significantly (p