Zhang Ye, Chang Chun Hao, Fan Xue Hai, Zuo Ting Ting, Jiao Ziwei
College of Biological Sciences and Technology, YiLi Normal University, Yining, 835000, People's Republic of China.
Key Laboratory for Resource Plants Protection and Utilization of Yili Valley in Xinjiang, Yining, 835000, People's Republic of China.
Sci Rep. 2024 Dec 28;14(1):31341. doi: 10.1038/s41598-024-82721-z.
Ice wine is produced from concentrated grape juice obtained by the natural freezing and pressing of grapes. The high sugar content of this juice has an impact on fermentation. To investigate the impact of the initial sugar concentration on the fermentation of ice wine, the initial sugar concentration of Vidal ice grape juice was adjusted to 370, 450, 500 and 550 g/L by the addition of glucose. The fermentation process was conducted at a temperature of 18 °C with Zymaflore ST yeast. To ensure optimal fermentation, the yeast assimilable nitrogen (YAN) in the grape juice was adjusted to 350 mg/L using a commercial nitrogen source. The initial sugar concentrations (370, 450, 500, and 550 g/L) were significantly negatively correlated with the number of viable yeast during active fermentation, the total consumption of sugar and YAN, and ethanol production (130.26, 117.83, 106.14, and 90.85 g/L) but positively correlated with the production of acetic acid (0.82-2.86 g/L) and acetaldehyde. Fermentation with initial sugar concentrations ≥ 500 g/L (500 and 550 g/L) produced ethanol (106.14 and 90.85 g/L) and excessive acetic acid (2.14 and 2.86 g/L), inhibited the esterification of n-butanol and n-hexanol, and promoted the production of isopentanol, isoamyl acetate, diethyl succinate, ethyl hexanoate and ethyl octanoate while increasing the production of 2-phenylethanol and isobutanol. The initial sugar concentration affected the production of glycerol, isobutanol, ethyl acetate, and diethyl succinate, but it did not affect the final contents of the ice wine. This study examined fermentation dynamics, including substrate consumption, yeast cell production, and the production of important metabolites such as ethanol, acetic acid, higher alcohols, and esters. Appropriate initial concentrations of YAN and sugar (below 500 g/L) and a relatively high ratio of glucose to fructose (between 1:1 and 1.7:1) is preferable for effective ice wine fermentation.
冰酒是由葡萄经自然冷冻和压榨得到的浓缩葡萄汁酿造而成。这种果汁的高糖含量会对发酵产生影响。为了研究初始糖浓度对冰酒发酵的影响，通过添加葡萄糖将维代尔冰葡萄汁的初始糖浓度调整为370、450、500和550 g/L。发酵过程在18℃下使用Zymaflore ST酵母进行。为确保最佳发酵，使用商业氮源将葡萄汁中的酵母可同化氮（YAN）调整至350 mg/L。初始糖浓度（370、450、500和550 g/L）与活跃发酵期间的活酵母数量、糖和YAN的总消耗量以及乙醇产量（130.26、117.83、106.14和90.85 g/L）呈显著负相关，但与乙酸（0.82 - 2.86 g/L）和乙醛的产量呈正相关。初始糖浓度≥500 g/L（500和550 g/L）的发酵产生了乙醇（106.1�和90.85 g/L）和过量的乙酸（2.14和2.86 g/L），抑制了正丁醇和正己醇的酯化反应，并促进了异戊醇、乙酸异戊酯、琥珀酸二乙酯、己酸乙酯和辛酸乙酯的产生，同时增加了苯乙醇和异丁醇的产量。初始糖浓度影响甘油、异丁醇乙酸乙酯和琥珀酸二乙酯的产量，但不影响冰酒的最终含量。本研究考察了发酵动力学，包括底物消耗、酵母细胞生成以及乙醇、乙酸、高级醇和酯等重要代谢产物的生成。适当的初始YAN和糖浓度（低于500 g/L）以及相对较高的葡萄糖与果糖比例（1:1至1.7:1之间）有利于冰酒的有效发酵。
