Enhancement of quality of rainbow trout (Oncorhynchus mykiss) flesh incorporating barley on diet without negative effect on rearing parameters

Abstract

[EN] Barley concentrations ranging from 0 to 32% (0B, 40B, 80B, 160B, and 319B) were incorporated into rainbow trout, Oncorhynchus mykiss (Walbaum) diets. The experiment started with an initial average fish weight of 127.72 +/- 5.65 g and finished when they reached commercial weight (final weight between 312 and 330 g) after 84 days. The inclusion of barley in the diets did not show a significant effect on growth and biometric parameters, fat and carbohydrate digestibilities; however, protein digestibility decreased significantly with the incorporation of barley on diets. Glucose levels increased significantly with barley concentration in the diet, and lactate and cortisol levels were also significantly affected after a stress period regardless of the diet. Meat quality was influenced as well by barley concentration. Lower water activity values and an enhancement in textural and color properties were observed in fish fed with the diet containing the highest barley concentration. Trout fed feed with higher concentrations of barley (160B) showed lower lipid oxidation levels than those fed with lower concentrations (control and 40B). The sensory panel found that fish fed with diets higher than 8% in barley content (80B) exhibited a brighter red color in the gills and a better texture; also, meat color became redder with a higher barley inclusion (160B and 319B), being all these sensory parameters correlated with fish freshness. Thus, results indicate that barley can be substituted for wheat fraction without any detrimental effect on production efficiency and enhancing fish quality.