Malolactic fermentation (MLF) is an important step in winemaking to improve wine quality by deacidification, increased microbial stability, and modified wine flavor. The phenolic composition of the wine influences the growth and metabolism of the lactic acid bacteria (LAB) used for MLF. Due to increased cultivation of fungus-resistant grape cultivars, the present study aimed to analyze the influence of stilbenes on MLF because stilbenes play an important role as phytoalexins in plants to counteract fungal pathogens. The analysis showed that the grapevine-shoot extract Vineatrol and the stilbenes ε-viniferin, ampelopsin A, r2-viniferin, and r-viniferin, as well as mixtures of the five stilbenes, decelerated malic acid degradation. This can be partially attributed to a reduced number of viable cells. However, the direct impact of stilbenes on the malolactic enzyme must also play a role, as shown by the finding that the viability of LAB stabilized, while at the same time, malic acid degradation was reduced. These results show that wines made from stilbene-rich grapes, such as fungus-resistant cultivars, might have a higher risk for a sluggish or incomplete MLF.

中文翻译：

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芪类可以损害酒糟酒球菌和植物乳杆菌菌株的苹果酸乳酸发酵

苹果乳酸发酵 (MLF) 是酿酒的重要步骤，通过脱酸、增加微生物稳定性和改变葡萄酒风味来提高葡萄酒质量。葡萄酒的酚类成分会影响用于 MLF 的乳酸菌 (LAB) 的生长和代谢。由于抗真菌葡萄品种的种植增加，本研究旨在分析芪对 MLF 的影响，因为芪在植物中作为植物抗毒素对抗真菌病原体发挥重要作用。分析表明，葡萄藤提取物 Vineatrol 和芪类 ε-viniferin、ampelopsin A、r2-viniferin 和 r-viniferin 以及五种芪类的混合物可减缓苹果酸的降解。这可以部分归因于活细胞数量的减少。然而，芪对苹果酸乳酸酶的直接影响也必须发挥作用，这一发现表明 LAB 的活力稳定，同时苹果酸降解减少。这些结果表明，由富含二苯乙烯的葡萄（例如抗真菌品种）酿制的葡萄酒可能具有较高的 MLF 缓慢或不完整的风险。