Effect of gutting on sensory, microbial and chemical characteristics, and fatty acid profile of Rainbow trout (Oncorhynchus mykiss) during storage at -18 o C

The aim of this study was to assess the effect of gutting on sensory, microbial and chemical characteristics, and fatty acid profile of rainbow trout (Oncorhynchus mykiss) during storage at -18 º C. To this end, 42 rainbow trout were prepared and divided into two groups. First group selected as whole fish and the other group were gutted, washed and were placed in selofan-pack and then were frozen at -18 °C. Afterwards, the quality characteristics (TVB-N, TBA, and PV), nutrient compounds (protein, fat, moisture and ash), fatty acid profiles, microbial community (total count and psychrophilic bacteria) and sensory indices were evaluated during 3 months of frozen storage. The results showed a different between two groups in moisture contents, PV, TBA and TVB-N parameters during storage (P< 0.05). Evaluation of fatty acid profile revealed 15 fatty acids. In both groups, the MUFA, SFA and PUFA were the most abundant fatty acids, respectively. During the storage period, the composition of fatty acids was found to be different between the two groups. Although microbial examinations showed no significant difference in the population of psychrophilic bacteria among the two groups, the load of total bacteria was found significantly (P< 0.05) different. Sensory evaluations revealed significant (P< 0.05) difference among all indices between the gutted and whole fishes. In addition, the texture and appearance changes were remarkable in gutted fish, meanwhile the odor and branch appearance were adequately preserved.