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关于黄酒发酵过程中pH的探讨 总被引:1,自引:3,他引:1
黄酒生产是一个复杂的生物化学变化过程,受发酵醪组成、pH值、温度、氧气、杂菌污染等物理和生物因素的影响。发酵过程pH的变化为:醪液加入发酵罐后酵母细胞生长与繁殖,pH下降;随后酵母代谢产酒精,pH值呈先上升后平稳之势;发酵末期pH值上升。同时发酵过程pH值还会影响酶的活性、酵母菌生长与繁殖和发酵醪中某些营养物质的分解或酵母中间代谢产物的解离。(孙悟) 相似文献
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温度对酵母的生长繁殖影响很大,在用固定化酵母进行糖蜜酒精发酵过程中,温度的变化主要影响酵母起种时间的长短,糖液流加速度,以及发酵速度的快慢。 相似文献
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苹果酿醋摇床发酵试验条件研究 总被引:8,自引:1,他引:7
以苹果浓缩汁为原料,分别采用葡萄酒酵母1450和醋酸菌AS.1.41进行液态酒精发酵和醋酸发酵,研究了温度、转速、发酵液相对装量三种摇床因素条件对醋酸发酵的影响。结果表明影响产酸速度的主要因素是相对装量,最佳试验条件为1/4相对装量、50℃、90rpm;影响酒精转酸率的主要因素是温度,最佳试验条件为27℃、1/4相对装量、120rpm。 相似文献
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几株酒精酵母的发酵性能比较 总被引:2,自引:0,他引:2
酵母菌种的好坏直接影响产品质量、设备利用率和产品产量,从而影响企业的经济效益。对1308菌株、1300菌株、安琪超酒酵母、奥特奇酵母产酒精的发酵、耐乙酸、耐乳酸、耐受酒精能力、耐受温度、耐渗透压、耐pH进行了发酵实验比较。结果表明,1308菌株、1300菌株、安琪超酒酵母、奥特奇酵母各有优缺点;菌株1308及安琪超酒酵母生产性能良好。 相似文献
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<正>基因重组酒酵母是近年来研究的热点之一,其发酵过程具有较高的产酒效率和产酒质量。然而,由于其遗传稳定性差、发酵条件苛刻等因素的影响,使得其发酵过程中存在一些问题,例如发酵时间长、低产酒率、酒精度不稳定等。为了优化控制基因重组酒酵母的发酵过程,需要研究其发酵关键参数,并提出针对性的控制策略。基因重组酒酵母是将外源基因导入酿酒酵母中,从而使其在发酵过程中产生新的代谢产物或改善原有代谢途径的能力。目前,已经应用于工业生产的基因重组酒酵母主要涉及酒精发酵、乳酸发酵等方面。其中, 相似文献
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酒精发酵过程中酿酒酵母海藻糖代谢的研究 总被引:15,自引:0,他引:15
研究了酿酒酵母在酒精发酵过程中酵母细胞内海藻糖的代谢。结果表明海藻糖的代谢受几种因素如底物浓度、发酵温度以及其他条件的调节与控制。在试验中对酿酒酵母细胞内海藻糖在整个酒精发酵过程中的生物功能作了简要的评价。 相似文献
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Fermentative capacity of Kluyveromyces marxianus and Saccharomyces cerevisiae after oxidative stress
《Journal of the Institute of Brewing》2017,123(4):519-526
Volatile compound production during alcoholic fermentation has been studied in the production of many beverages. Temperature, yeast strain, nutrients and pH have been identified as important factors in the production of volatile compounds. In addition, other factors could influence this production during the fermentation process as well. Oxidative stress could occur during yeast biomass production because oxygen is an essential nutrient that is added to the growth medium. The fermentation parameters and the volatile compound production of one Saccharomyces cerevisiae strain (MC4) and two Kluyveromyces marxianus strains (OFF1 and SLP1) were evaluated in relation to fermentation parameters after oxidative stress induced by hydrogen peroxide or menadione. These yeasts were compared with S. cerevisiae W303–1A and showed significant differences in ethanol production, ethanol yield and maximum ethanol production rate. K. marxianus (OFF1) showed better fermentative capacity after oxidative stress. The higher alcohol production decreased after oxidative stress by >35% after 72 h fermentation time, and the amyl alcohol decreased at a higher level (>60%); however, the isobutanol production increased after oxidative stress between 1.5 and 4 times. The yeasts produced significant concentrations of esters however ethyl lactate, ethyl caprylate and the ethyl caproate were not detected in the control fermentation, while in the stress fermentation they accounted for up to 3 mg/L. These results demonstrate that oxidative stress can play an important role in the final aroma profile; but it is necessary to guarantee adequate yeast growth to obtain the volatile compounds desired. Copyright © 2017 The Institute of Brewing & Distilling 相似文献
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Brewery yeast needs traces of oxygen for the biosynthesis of unsaturated fatty acids and ergosterol. Owing to the increase in cell mass during primary fermentation the concentrations of these essential lipids decrease and thereby affect the physiological condition of the yeast. When the sterol concentration of whole cells has decreased to 0.2 to 0.3 mg per 100 mg dry yeast, the yeast changes its metabolism. This metabolic change is revealed by a decrease in acetoin concentration. The absorption of wort nutrients and consequently the efficiency of growth is at this point also greatly reduced. The ratio between yeast growth and mole ethanol formed (i.e. the molar growth yield) decreases greatly during wort fermentation. A close correlation between molar growth yield and the change in acetoin metabolism can be observed. This metabolic change occurs when the ratio between yeast growth and ethanol formed is in the range of 8.3 to 9.1, averaging 8.7 g/mole. 相似文献