Effect Of Saccharifying Agent And Leaveningagent On The Accumulation Of Higher Alcohols And Urea In Fermentation Process Of Chinese Rice Wine

Higher alcohols are by-products during the fermentation of Chinese rice wine main flavor components and main flavor substances in Chinese rice wine. Adequate quantity of higher alcohols could improve the harmony of Chinese rice wine, but superfluous higher alcohols content would cause strongly drunk, commonly known as "headache". Therefore, it is very important to control the content of higher alcohols for the development of Chinese rice wine. Urea in wine mainly comes from the decomposition of that arginase decomposes L-arginine during the yeast metabolism of is a small part of raw materials directly into the outside, most of the rest comes from the yeast metabolism by arginase produced by decomposition of L-arginine. Urea could slowly hydrolyze under conditions of heating, acid and alkaline. Because most urea can react with alcohol to form toxic urethane in process of wine making, control the urea content in Chinese rice wine is significantly.For these reasons, this paper studied the influence on higher alcohols and urea content by different saccharifying agent (wheat koji, enzymes) and leavening agents (type of yeast, yeast inoculation, yeast proliferation time) in fermentation process of Chinese rice wine. Higher alcohols and urea were detected by gas chromatography and diacetyl oxime spectrophotometric detection, respectively. The results were as follows:Raw wheat koji which contains different strains is cultured by raw materials under natural state, cooked wheat koji contains single strain and is cultured by Aspergillus niger under artificial conditions. By comparing the performance of two kinds of wheat koji, the results show that:the diastatic power of raw wheat koji and cooked wheat koji is775mg/gh and856mg/g·h, respectively. The liquefaction power is1.37g/g·h and7.38g/g·h, respectively. The protein-catabolizing power is19.5ug/g·min and174μg/g·min. The diastatic power of cooked wheat koji is10%higher than that of raw wheat koji, the liquefaction power and protein-catabolizing power of cooked wheat koji are5and8times than that of raw wheat koji, respectively.Study on the influence on the accumulation of higher alcohols and urea content by raw wheat koji. Results indicated that:the content of higher alcohols dropped off with the additive amount of raw wheat koji decreased from25kg to20kg, the minimum content was338.82mg/L. When the additive amount of raw wheat koji was less than20kg, the content of higher alcohols increased gradually, and the content of higher alcohols could reach518.25mg/L when the raw wheat koji was totally absent. The content of urea was increased with increasing additive amount of raw wheat koji, it was12.194mg/L when the additive amount was25kg, and the content was5.371mg/L when the additive amount was0. Considering the taste and content of higher alcohols and urea in Chinese rice wine, the25kg additive amount of raw wheat koji was chose for the proper scheme.Study on the influence on the accumulation of higher alcohols and urea content by cooked wheat koji. Results indicated that:the influence of cooked wheat koji for higher alcohols was unconspicuous.The content of urea was increased with increasing additive amount of cooked wheat koji. The results indicated that No.2sample showed better taste, the content of urea, higher alcohols, ammonia nitrogen was19.180mg/L,301.32mg/L,0.611g/L, respectively. The alcoholic strength and acidity was17.4%Vol and5.89g/L, respectively.Study on the influence on the accumulation of higher alcohols and urea content by enzymatic preparations. Results indicated that:the content of higher alcohols and the content of urea in fermented liquid ware decreased with increasing additive amount of enzymatic preparation. When the additive amount of mixture wheat koji was20kg, enzymatic preparation was84%, the content of higher alcohols was the lowest amount312.83mg/L, the urea was8.660mg/L which didn’t significantly differ from the the lowest amount6.56mg/L, total sugar was16.2g/L, ammonia nitrogen was0.368g/L, alcoholic strength was18.2%Vol. The results were in agreement with government standard, and the taste of Chinese rice wine was good. Therefore, the No.3sample was chose as the proper scheme which the additive amount of mixture wheat koji was20kg, enzymatic preparation was84%.Study on the influence on the accumulation of higher alcohols and urea content by6different kind of yeasts (g-1, g-2, d-3, d-4, d-13, d-14). Results indicated that:rice wines fermented by high-yield yeasts d-3and d-4had lower content of higher alcohols and urea, which were in favor of the control of higher alcohols. Rice wines fermented by low-yield yeasts d-13and d-14had higher content of higher alcohols and urea, which were bad for the fermentation of Chinese rice wines. Therefore the content of urea and the alcoholic strength didn’t have positive correlation.Study on the influence on higher alcohols and urea content by five levels of yeasts inoculation (1.0×105cell/mL,1.0×106cell/mL,1.0×107cell/mL,1.0×108cell/mL,1.0×109cell/mL). The content of higher alcohols and urea on the level1.0×107cell/mL was411.76mg/L and18.090mg/L, respectively, which was the lowest amount in the five levels. So the proper inoculation of yeasts was within1.0×10’ cell/mL in the fermentation of Chinese rice wine.Study on the influence on higher alcohols and urea content by new process which was saccharified firstly and then fermented and controlling the time of yeasts proliferation. After fermentation, the content of higher alcohols in the first three days was403.15mg/L、435.53mg/L、467.48g/L, respectively, the content of urea was16.437mg/L、19.389mg/L23.160mg/L. The content of higher alcohols and urea increased with the yeast inoculation increasing within a certain range. Therefore the yeasts inoculation time should be strictly controlled in the process of rice wine production.