| In this thesis, breeding S. cerevisiae and Asp. flavus strains, screening appropriative rices and optimizing process conditions were studied, in order to meet the need of production and market, to improve the quality and yield of Chinese rice wine(CRW) and to reduce its cost furthest.To breed diastatic fermentation strains. We gained one thermal-tolerant(38 C) yeast mutant (S. cerevisiae)YS6.2.5 which came from (S. cerevisiae)YS that was controlled by ethanol and heat impacting, UV radiating on its cell and protoplast, combined high temperature domesticating and TTC coloration in plate. Mutant YS6.2.5 had advantages of stable transmissibility, fast-synchronous growth velocity, better physiological tolerance, strong fermenting power(alcoholicity was 9.0% at 30 C and 6.5% at 38 C), soft taste and typical-particular flavor of finished CRW. To (Asp. flavus)YA, firstly, via multi-analysis tests, we got the optimal separatio conditions of transparent-loop in plate: 1.2% soluble starch, 0.8% yeastrel, 0.7ml iodine solution per 100ml 0.5% water-agar(top layer), 2% agar(bottom layer), color development at 15 C. Then, (Asp. flavus)YA was mutagenized by UV, UV-LiCl and BaCOa, combined natural selection and transparent-loop in plate, and we obtained one unaflatoxigenic mutant (Asp. flavus)YA4.9 which had strong diastatic power (higher 103.46% than YA). Finally, via single-analysis tests, we obtained the optimal processes of making moldy bran: 100% water, 1.5% NaNO3(mold starter was 2% (NH4)2S04)), 0.05% KH2PO4, 0.03% MgS04, initial pH4.0~4.5, culturring 30-32 hours (mold starter was 4~5 days) at phased temperature, and the diastatic power of mature moldy bran was 38.335 103u/g koji mostly, higher 34.45% than unoptimizable koji. Stable transmissibility, fast growth and fermentation velocity, dense-dumpy mycelium, high wine-ratio and excellent flavor was YA4.9 strain' s properties.To screen appropriative rices. Comparing the characteristics of physico-chemical, brewing, fermenting and finished wine of seven different rice strains which were genetic from the same rice species, we selected strain3 as the rice-appropriative of dry CRW, and strain7 of rice wine(RW). The properties of strain3 were as follows: grain was big-full-chalky and aromatic, fermentation was controlled easily, wine-ratio was the higest(239.05%), the finished CRW style was typical. Theproperties of strain? were: grain was small-part-chalky, amylopectin/amylose ratio(a/a ratio, namely starchiness) was the highest(35.38, similar to sticky rice), the finished RW had high juice ratio and high oligosaccaride content and particular taste. It was shown that the effects of a/a ratio on dry CRW was less and on RW was more promient. Namely, the rice was suitable to brew modem-light RW when a/a ratio was 9.86-35.38, to brew traditional-rich RW when a/a ratio was higher than 35.58, and not suitable to brew RW when a/a ratio was lower than 9.86 because of the stronger bitterness. Thus, we offered RW manufacture scientific directions for selecting rice and improving technology.To control sound fermenting process. Rice type, soaking and cooking rice, the quality and dosage of moldy bran and yeast starter, initial temperature, main and post fermentation temperature were studied, and we arrived at the optimal fermenting process of dry CRW: soaking rice 72 hours, cooking rice 25~30 minutes, 9% mix moldy brans, 7% mature yeast starters, initial temperature at 26 1 C, main fermentation prophase at 30 C and post fermentation at 8~15 C, by which not only improved the quality and yield but avoided the mash acidification effectively. The effects of phytic acid(PA) on CRW were studied, it was shown that the optimal concentration of PA as stimulant on S. cerevisiae and Asp. flavus strains' growth-and-fermentation were 0.10% and 0.20% respectively and as clearer on aggregates was 0.04%. As a result, S. cerevisiae strains' alcoholicity increased by 13.16% at 96 hours and its alcohol tolerance strengthened from 16% to 20%, Asp. flavus strains' diastatic power increased by 24.84% m... |
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