Oxymyoglobin and lipid oxidation in yellowfin tuna (Thunnus albacares) loins

The present study characterized oxymyoglobin (OxyMb) and lipid oxidation in yellowfin tuna, and determined the influence of various aldehydes on tuna OxyMb stability in vitro. Surface metmyoglobin accumulation and lipid oxidation increased in tuna steaks with time (P < 0.05). In both tuna steaks and patties, a* values decreased (P < 0.05) and hue angle increased following 6 d storage (P < 0.05). Sensory evaluation demonstrated increased discoloration and decreased odor acceptability in refrigerated steaks and patties over time (P < 0.05). Hexanal, hexenal, and 4-hydroxynonenal enhanced OxyMb oxidation relative to controls in vitro (P < 0.05). These results indicate a relationship between myoglobin and lipid oxidation in tuna, and that aldehydes known to be produced during lipid oxidation can accelerate tuna OxyMb oxidation in vitro.