Influence of slaughtering method on some aspects of quality of gilthead seabream and smoked rainbow trout

The effects of several slaughter methods on the quality of fresh and smoked trout and fresh gilthead seabream
were evaluated during storage at 2◦C. Electrically stunned trout had slower ATP depletion of raw muscle
and lower lipid oxidation in smoked product during storage. Gilthead seabream immersed in an ice slurry
(IS group) after the harvest showed a more regular ATP depletion than in fish exposed to CO2. Nevertheless,
in the case of the IS group, self-initiated behaviour, response to handling and breathing all ceased only after
15–20 min, whereas carbon dioxide-stunned fish appeared dead after 5 min. However, gilthead seabream group
having slower ATP depletion also showed lower lipid oxidation of muscle during storage. In both species this
could be due to the rapid conversion of xanthine dehydrogenase to xanthine oxidase induced by the rapid
consumption of ATP. Xanthine oxidase, in the presence of redox iron and reintroduced oxygen, can produce
hydrogen peroxide and, consequently, hydroxyl radicals.