Evaluation of chemical composition, color change and fillet yield with increase weight of rainbow trout (Oncorhynchus mykiss)

Trout is the most important and high consumption fish in the country proffering to market in weight of 250-300 gr, though in the recent years observed, market demands and more of the processing plants is in higher weight of this range in the country. Whereas, quality changes and chemical of the muscle, fatty acid profile and filet yield can be react of weight gain, since learn of weight gain effects on said parameters is very important for consumer of economic viewpoint and nutritional quality. For this purpose provide seventy five trout with average weights about 300, 500 and 700 gr with equivalent culture condition from a fish culture farm in Golestan province and transport to the processing laboratory of Gorgan university of agricultural sciences and natural resources in adequate condition together ice. After doing various process of primeval preparation, above parameters studied. Results showed Moisture and protein don’t show significant difference in treatments whereas fat and ash have significant difference in certain treatments. Analysis of a*, b* and l* index showed significant difference in some treatments. Also fillet yield have significant difference in all treatments and fillet yield increase with weight gain. Therefore, total results showing with trouts weight gain from 250 gr into higher weights and particular than the weight of 500 gr, flesh of this fish of nutritional value, fillet yield and sensory characteristic stand in advantage condition, though higher and lower weight be outstanding in certain feature too.