Abstract

Alcoholic fermentation is a crucial step of winemaking, during which yeasts convert sugars to alcohol and also produce or biotransform numerous flavour compounds. In this context, nutrients are essential compounds to support yeast growth and ultimately ensure complete fermentation, as well as optimized production of flavour compounds over that of off-flavour compounds. In particular, the vitamin thiamine not only plays an essential cofactor role for several enzymes involved in various metabolic pathways, including those leading to the production of wine-relevant flavour compounds, but also aids yeast survival via thiamine-dependent stress protection functions. Most yeast species are able to both assimilate exogenous thiamine into the cell and synthesize thiamine de novo. However, the mechanism and level of thiamine accumulation depend on several factors. This review provides an in-depth overview of thiamine utilization and metabolism in the model yeast species Saccharomyces cerevisiae, as well as the current knowledge on (1) the intracellular functions of thiamine, (2) the balance between and regulation of uptake and synthesis of thiamine and (3) the multitude of factors influencing thiamine availability and utilization. For the latter, a particular emphasis is placed on conditions occurring during wine fermentation. The adequacy of thiamine concentration in grape must to ensure successful fermentation is discussed together with the effect of thiamine concentration on fermentation kinetics and on wine sensory properties. This knowledge may serve as a resource to optimise thiamine concentrations for optimal industrial application of yeasts.

Key points

• Thiamine uptake is preferred over biosynthesis and is transcriptionally repressed.

• Multiple factors affect thiamine synthesis, availability and uptake for wine yeast.

• Thiamine availability impacts fermentation kinetics and wine’s sensory properties.

中文翻译：

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硫胺素：葡萄酒酒精发酵过程中酵母的关键营养素

摘要

酒精发酵是酿酒的关键步骤，在此过程中，酵母将糖转化为酒精，并产生或生物转化多种风味化合物。在这种情况下，营养素是支持酵母生长并最终确保完全发酵以及风味化合物与异味化合物的优化生产的必需化合物。尤其是，维生素硫胺素不仅对参与各种代谢途径的几种酶（包括那些导致产生酒相关风味化合物的酶）起着至关重要的辅因子作用，而且还通过硫胺素依赖性应激保护功能帮助酵母存活。大多数酵母菌种既能够将外源硫胺素吸收到细胞中，又可以从头合成硫胺素。然而，硫胺素积累的机制和水平取决于几个因素。这篇综述提供了模型酵母菌种中硫胺素利用和代谢的深入概述酿酒酵母，以及有关（1）硫胺素的细胞内功能，（2）硫胺素的摄取和合成之间的平衡和调节以及（3）影响硫胺素可用性和利用的多种因素的当前知识。对于后者，特别强调在葡萄酒发酵期间发生的条件。讨论了葡萄中硫胺素浓度是否足够以确保成功发酵，以及硫胺素浓度对发酵动力学和葡萄酒感官特性的影响。该知识可作为优化硫胺素浓度以实现酵母最佳工业应用的资源。

关键点

•硫胺素的摄取优于生物合成，并且在转录上受到抑制。

•多种因素影响葡萄酒酵母中硫胺素的合成，可用性和摄取。

•硫胺素的可用性会影响发酵动力学和葡萄酒的感官特性。