Estabilidade lipídica de filés de jundiá (Rhamdia quelen)

Abstract

This work was aimed at studying lipid stability of silver catfish (Rhamdia quelen) fillets. The influence of the inclusion (5%) of soybean or rice oil in silver catfish diet and vacuum packaging on lipid and color stability of raw silver catfish fillets was evaluated during frozen storage (18 months). Besides, the influence of seven cooking methods (boiling, conventional baking, microwave baking, grilling, deep frying in soybean oil, canola oil, or partially hydrogenated vegetable oil) on the oxidation, proximate, and fatty acid composition of fillets was also evaluated. The different diets had no effect on the proximate composition of the fish fillets. The content of thiobarbituric acid reactive substances (TBARS, lipid oxidation index) of fillets from both diets increased after 12 months of storage with or without vacuum, but this increase was higher in fish fed with soybean oil. Color parameters were not affected by the vacuum storage or diet, but most parameters (a*, b*, chroma, and Hue values) were affected by the time of storage. Hue value showed that raw fillets tended to yellowness and after 18 months of frozen storage became greener. The content of various fatty acids in fillets was influenced by the type of vegetable oil used in the diet, but n-3/n-6 polyunsaturated fatty acids ratio and unsaturated/saturated ratio did not differ between diets. All cooking methods evaluated reduced moisture and increased protein content. Fat content was higher in the fried fillets. The free fatty acid content of fillets was significantly reduced by the different cooking methods, while conjugated dienes and peroxide values decreased for all fried samples, but remained constant in the samples submitted to the other cooking methods. Boiling and baking increased TBARS, while grilling and frying did not change TBARS. Boiling, baking, and grilling did not affect the silver catfish fillets fatty acid composition. Frying in canola oil increased n-3/n-6 ratio, in soybean oil increased general polyunsaturated fatty acid content, and in hydrogenated vegetable oil incorporated trans fatty acids in the fillets. Results indicated that fillets from silver catfish fed diets with soybean or rice oil have different lipid profile and lipid stability during frozen storage. Frying silver catfish fillets in canola oil could increase the low n-3/n-6 polyunsaturated fatty acids ratio of raw silver catfish fillets.