Effect of Soybean Meal‐based Diets on the Product Quality of Rainbow Trout Fillets

Abstract

ABSTRACT: This study investigated the long‐term effects of soybean meal (SBM)‐based diets on rainbow trout quality. Two levels of SBM inclusion diets, 20% and 40%, were employed and compared with a fish meal control diet. Rainbow trout were fed one of the three diets for 6 mo, then harvested and filleted. Proximate composition, color, lipid oxidation and sensory quality of the fillets were evaluated. Thiobarbituric acid reactive substances (TBARS) and headspace propanal in ground fillets stored at 4 °C were measured over a 9‐d period. Tristimulus color was measured on day 2 and day 13 of refrigerated storage. Sensory evaluation included discriminatory (difference) and affective (acceptance) testing. TBARS and propanal in the trout fed the highest (40%) SBM level were significantly lower than in the control and trout fed the 20% SBM diet. Significant differences in color were also recorded during refrigerated storage. Sensory difference testing revealed a significant difference between the trout fed the 40% SBM and the control. No significant differences were observed in the acceptability ratings of trout fillets from the three different dietary treatments.