1Faculty of Agriculture, Kochi University, Nankoku, Kochi 783-8502, 2JST-CREST, Chiyoda, Tokyo 102-0076, Japan
In a previous study, we showed that feeding young yellowtail with a yuzu peel paste-supplemented diet (Yuzu diet; 50 g of yuzu peel paste in 1,450 g of diet, wet basis) for 10 and 12 weeks prevented the discoloration of dark muscle without producing any negative effects in the yellowtail. This study was conducted to confirm the amount of Yuzu diet required for preventing the discoloration and lipid oxidation of dark muscle during storage and for maintaining its efficacy. Yuzu diet did not show any negative effects on the growth of yellowtail. The discoloration and lipid oxidation of dark muscle were prevented in fish fed with the Yuzu diet for 3 weeks and 3 and 4 weeks, respectively. However, these effects disappeared following 5 days of starvation after 4 weeks of the feeding. These results indicate that at least 3 weeks of feeding (>1.0% body weight intake of yuzu peel) is required for preventing discoloration and lipid oxidation. Furthermore, the effects might last for less than 5 days after the feeding is stopped.