Changes of radical-scavenging capacity and ferrous reducing power in chub mackerel Scomber japonicus and Pacific saury Cololabis saira during 4 °C storage and retorting

To clarify the effects of freshness of raw fishes and boil-retort process on the antioxidant activities, we determined stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging capacity and ferrous reducing power in the ethanol extract solution of chub mackerel Scomber japonicus and Pacific saury Cololabis saira meat before and after retort process (115 °C for 80 min). The antioxidant activities in boiled (mizu-ni) and canned fish were also investigated. The mizu-ni can products contain only fish meat and little salt. The radical-scavenging capacity was increased about ten times in chub mackerel and about six times in Pacific saury by the retort treatment. Both antioxidant activities of raw chub mackerel meat increased during 10 days storage at 4 °C. On the other hand, the increasing of antioxidant activity in the stored and retorted meat was observed until four days storage. In the case of mizu-ni canned products, the antioxidant activities were high in common-grade cans rather than high-grade cans. Almost the antioxidant activities shown in this study were correlated with absorbance at 245 nm. We consider that the results about differences of antioxidant activities between raw and retorted fishes or fresh and several day stored fishes are useful for the food functions and safeties.