Process Study On Higher Alcohols Control In Chinese Rice Wine

Higher alcohols are by-products of yeast metabolism during the fermentation of Chinese rice wine and main flavor substances in Chinese rice wine. Adequate quantity of higher alcohols could make Chinese rice wine with full and enjoyable taste and improve the harmony of Chinese rice wine. However, superfluous higher alcohols content would bring off-flavor in Chinese rice wine and cause strongly drunk, commonly known as "headache". Therefore, it is very important that higher alcohols control to improve Chinese rice wine quality.For these reasons, this paper mainly studied the influence on higher alcohols content by varieties of raw materials, primary fermentation temperature, afterfermentation temperature, addition of wheat starter and yeast inoculation in Chinese rice wine fermentation. Finally, the process conditions that obviously influnced higher alcohols content were optimized. The research results were as follows.Two kinds of glutinous rices, two kinds of polished round-grained rices and two kinds of polished long-grained nonglutinous rices were separately used as raw materials to study their influence on higher alcohols content. The process parameters were as follows:The rice was150grams, the ratio of material to water was1:1, the addition of wheat starter was15%of the rice's weight, and the yeast inoculation was1.0×107cell/mL. The fermentations were conducted at28℃for5days and15℃for15days. The results showed that the content of higher alcohols of glutinous rice wines were obviously more than those of polished round-grained rice wines and polished long-grained nonglutinous rice wines, and the content of higher alcohols of polished round-grained rice wines were slightly more than those of polished long-grained nonglutinous rice wines. But the mashes of polished round-grained rices and polished long-grained nonglutinous rices were pasty in the incipient fermentation, and the wines with more lees and lower alcohol yield after fermentation.Study on the influence on higher alcohols content by primary fermentation temperature. The process parameters were as follows:The glutinous rice was150grams, the ratio of material to water was1:1, the addition of wheat starter was15%of the rice's weight, and the yeast inoculation was1.0×10'cell/ml.. The fermentations were separately conducted at26℃,28℃,30℃,32℃,34℃for5days and then at15℃for15days. The results showed that higher alcohols content increased fast in the primary fermentation process. When the primary fermentation temperature was lower than30℃, higher alcohols content increased with the temperature rising, and when the primary fermentation temperature was higher than30℃, higher alcohols content decreased with the temperature rising.Study on the influence on higher alcohols content by afterfermentation temperature. The process parameters were as follows: The glutinous rice was150grams, the ratio of material to water was1:1, the addition of wheat starter was15%of the rice's weight, and the yeast inoculation was1.0×10'cell/mL. The fermentations were conducted at28℃for5days and then separately at11℃,13℃,15℃,17℃,19℃for15days. The results showed that higher alcohols content increased lightly in the afterfermentation process, and higher alcohols content increased with the temperature rising.Study on the influence on higher alcohols content by addition of wheat starter. The process parameters were as follows:The glutinous rice was150grams, the ratio of material to water was1:1, the addition of wheat starter was separately11%,13%,15%,17%,19%of the rice's weight, and the yeast inoculation was1.0×10'cell/mL. The fermentations were conducted at28℃for5days and then at15℃for15days. The results showed that higher alcohols content increased when the addition of wheat starte was too high or too low. When the addition of wheat starter was lower than15％,higher alcohols content increased with the addition of wheat starter decreasing,and when the addition of wheat starter was higher than15％,higher alcohols content increased with the addition of wheat starter inereasing.Study on the influence on higher alcohols content by yeast inoculation.The process parameters were as follows:The glutinous rice was150grams, the ratio of material to water was1:1,the addition of wheat stater was15％of the rice's weight, and yeast inoculation was separately0.6×107cell/mL,0.8×107cell/mL,1.0×107cell/mL,1.2×107cell/mL and1.4×107cell/mL.The fermentations were conducted at28℃for5days and then at15℃for15days. The results showed that yeast inoculation influnced obviously on higher alcohols content. When the yeast inoculation was lower than1.0×107cell/mL,higher alcohols content decreased with the yeast inoculation increasing, and when the yeast inoculation was higher than1.0×107cell/mL. higher aleohols content increased with the yeast inoculation inereasing.Response surface optimization of Chinese rice wine proeess conditions. Based on the Box-Benhnken central composite experiments, this study optimized primary fermentation temperature, addition of wheat starter and yeast inoculation the three process conditions which influenced obviously on higher alcohols content by response surface. The results showed that the influence of primary fermentation temperature on higher alcohols content was extremely significant, the influences of addition of wheat starter and yeast inoculation on higher alcohols content were significant, the interaction between the factors was not obvious. The optimal conditions were determined as follows:primary fermentation temperature was27.47℃, addition of wheat starter was14.41%. yeast inoculation was0.98×10'cell/mL, under the optimal conditions, higher alcohols content were512.91mg/L...