Changes of superoxide dismutase activities in barley during the process of malting and storage

Activities differences of superoxide dismutase (SOD) in twenty-eight varieties of domestic barley and their changes under different malting processes and storage conditions were investigated. The results show that larger activities differences existed among different barley varieties, most of which are between 30 and 60U?g-1 and can be used to brew good quality beer. Superoxide dismutase activity gradually increased during steeping and germination. The increasing rate of superoxide dismutase activities are enhanced when gibberellin acid (GA3) was added during steeping while quantities of superoxide dismutase are similar with that in untreated barely. Superoxide dismutase activity sharply denaturalized during kilning and 50 percentage of it survive at the end of kilning. The shorter time of kilning, the less was denaturation degree of SOD. The higher moisture of malt at end of kilning is beneficial to reactivation of superoxide dismutase. In the first twenty days of storage, superoxide dismutase in each sample of malt reactivats more quickly and tendency becomes gentle after that. And the appropriate temperature for malt storage was 25℃.