Berthels N J, Cordero Otero R R, Bauer F F, Thevelein J M, Pretorius I S
Department of Viticulture and Oenology, Institute for Wine Biotechnology, Stellenbosch University, Victoria Street, Stellenbosch ZA-7600, South Africa.
FEMS Yeast Res. 2004 May;4(7):683-9. doi: 10.1016/j.femsyr.2004.02.005.
While unfermented grape must contains approximately equal amounts of the two hexoses glucose and fructose, wine producers worldwide often have to contend with high residual fructose levels (>2 gl(-1)) that may account for undesirable sweetness in finished dry wine. Here, we investigate the fermentation kinetics of glucose and fructose and the influence of certain environmental parameters on hexose utilisation by wine yeast. Seventeen Saccharomyces cerevisiae strains, including commercial wine yeast strains, were evaluated in laboratory-scale wine fermentations using natural Colombard grape must that contained similar amounts of glucose and fructose (approximately 110 gl(-1) each). All strains showed preference for glucose, but to varying degrees. The discrepancy between glucose and fructose utilisation increased during the course of fermentation in a strain-dependent manner. We ranked the S. cerevisiae strains according to their rate of increase in GF discrepancy and we showed that this rate of increase is not correlated with the fermentation capacity of the strains. We also investigated the effect of ethanol and nitrogen addition on hexose utilisation during wine fermentation in both natural and synthetic grape must. Addition of ethanol had a stronger inhibitory effect on fructose than on glucose utilisation. Supplementation of must with assimilable nitrogen stimulated fructose utilisation more than glucose utilisation. These results show that the discrepancy between glucose and fructose utilisation during fermentation is not a fixed parameter but is dependent on the inherent properties of the yeast strain and on the external conditions.
未发酵的葡萄汁中葡萄糖和果糖这两种己糖的含量大致相等，但全球的葡萄酒生产商常常不得不应对高残留果糖水平（>2 g l⁻¹），这可能导致成品干型葡萄酒出现令人不悦的甜味。在此，我们研究了葡萄糖和果糖的发酵动力学以及某些环境参数对葡萄酒酵母利用己糖的影响。使用天然鸽笼白葡萄汁（其中葡萄糖和果糖含量相似，各约110 g l⁻¹），在实验室规模的葡萄酒发酵中对包括商业葡萄酒酵母菌株在内的17株酿酒酵母菌株进行了评估。所有菌株都表现出对葡萄糖的偏好，但程度各异。在发酵过程中，葡萄糖和果糖利用的差异以菌株依赖的方式增加。我们根据葡萄糖与果糖利用差异的增加速率对酿酒酵母菌株进行了排名，结果表明这种增加速率与菌株的发酵能力无关。我们还研究了在天然和合成葡萄汁的葡萄酒发酵过程中添加乙醇和氮对己糖利用的影响。添加乙醇对果糖利用的抑制作用比对葡萄糖利用的抑制作用更强。向葡萄汁中添加可同化氮对果糖利用的刺激作用比对葡萄糖利用的刺激作用更大。这些结果表明，发酵过程中葡萄糖和果糖利用的差异不是一个固定参数，而是取决于酵母菌株的固有特性和外部条件。
