Studied On Rhizopus's Influence On Degradation Of Barley During Malting

Rhizopus strain was selected and its influence on improving domestic malt quality was investigated. Three Rhizopus strains, such as Rhizopus oryzae CICC 3102, Rhizopus stolonifer CICC 40315 and Rhizopus chinensis CCTCC M201021 were used. It was indicated that Rhizopus stolonifer CICC 40315 was the best suitable strain with vigorous mycelium. The growing and enzymic producing optimal pH was 7.0 and 9.0, respectively, the enzyme was produced earlier and longer, which was consistent with barley during germination. It was confirmed that theβ-glucan was degraded by the enzyme which was excreted by microorganism in the malt.β-glucan content was decreased by 74.8 %. The activity ofβ-glucanase and xylanase was increased by 193.0 % and 15.2 %, respectively.Activated spores of Rhizopus stolonifer were inoculated during steeping stage. The influence of steeping temperature, germinating evening temperature and drying time of 45℃onβ-glucan content of malt were investigated. It was showed that the regression model was fitted with the actual process well by regression coefficient and analysis.Based on the results of response surface methodology, the optimal conditions of microbial malting thatβ-glucan was least in malt were as follows: steeping temperature was 20℃, germinating evening temperature was 15℃, drying on 45℃for 5h. Theβ-glucan content of malt was reached to 18.8(mg/100db), decreased by 28.4 % than previously content. Degradation of microbial malt was good and composition of organic acid has a favorable effect on flavor of beer. There was no abnormity performance during fermentation of microbial malt, which approved microbial malt's workability.Low dosage of gamma irradiation have a little effect on germinate activity of barley, but high dosage could markedly effected germinate activity and delaied germination. The higher dosage was used, the restrainable effect on sprout was more marked. Proper dosage ofγirradition could decreasedβ-glucan in malt and decreased the viscosity. The content ofβ-glucan was lowest andβ-glucanase activity was highest whenγirradition was 6 KGy.γirradition could impacted degradation of malt and changed entironment of barley more fitable for starter culture, the variety organic acid in malt was associated with metabolism of starter culture. Degradated enzyme from microbe got inside of malt by mycelium, whose invading was the key for malt's dissolution. Mircobial malt was safe for use, having no normal mycotoxins, and Rhizopus stolonifer could restrained deleterious strains that can excreted deoxynivalenol.