Effects of fat content and fatty acid composition of Nagara River ayu on its quality as a food ingredient

• Published in: Journal for the Integrated Study of Dietary Habits Vol. 33; no. 4; pp. 193 - 198
• Main Authors: Otsu, Yumiko, Funahashi, Yumi
• Format: Journal Article
• Language: English; Japanese
• Published: THE JAPAN ASSOCIATION FOR THE INTEGRATED STUDY OF DIETARY HABITS 2023
• ISSN: 1346-9770; 1881-2368
• DOI: 10.2740/jisdh.33.4_193

Ayu (Plecoglossus altivelis) living in the Nagara River in Gifu Prefecture were caught at three sites upstream,midstream and downstream to test fat content and fatty acid composition in edible portions. In the lower reaches, Ayu were fished twice, in summer (from June to August) and fall (October).　The fat content in edible parts was higher in the order of midstream ayu, Depending on where they were caught,the percentage of the fat content changed.Midstream Ayu is the highest, and Downstream Ayu (June to August) is significantly low.　Comparison of fatty acid composition showed significant differences in the proportions of several fatty acids. Palmitic acid was more abundant in upstream and midstream Ayu. The proportion of icosapentaenoic acid was higher in downstream Ayu (October), and that of arachidonic acid was higher in downstream Ayu (June-August) and (October).　The fat content and fatty acid composition of edible parts differed among downstream, midstream, and upstream Ayu, even in the same river. This was attributed to the different flow velocities and feeding conditions of epiphytic algae in each habitat. It has also been shown that Ayu's unique aroma is produced by the oxidation of certain fatty acids, suggesting that differences in fat content and fatty acid composition may affect the flavor of ayu, such as fat content and aroma, rather than merely differences in nutritional composition.