Rainbow Trout (Oncorhynchus mykiss) Skin as Potential n-3 Fatty Acid Source

Purpose: The rise in the demand and the limited availability of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids claim to produce these important long chain polyunsaturated fatty acids (LCPUFA) from novel sources. Skin of rainbow trout is a fish industry by-product but still contains valuable LCPUFA amounts with great potential applications in human nutrition and health. This study aimed to explore the nutritional composition of rainbow trout skin for its use as source of n-3 LCPUFA and its composition modification according to fish diet. Methods: Rainbow trout were fed three diets including increasing substitution levels of fishmeal with full-fat black soldier fly (Hermetia illucens) larvae meal (0%, 25%, 50% substitution levels) over 98 days. Results: DHA was the major representative of the n-3 LCPUFA in the skin of all dietary groups, being the H25 group the richest in this fatty acid. Conclusions: The present study shows that the skin of rainbow trout can be a promising source of n-3 LCPUFA. Reusing the skin of farmed fish represents a possible way to decrease food industry by-products, to reduce n-3 LCPUFA shortfall and could lead to the development of functional foods and nutritional supplements including n-3 LCPUFA from fish skin.