Department of Chemistry and Quality Control, Höhere Bundeslehranstalt und Bundesamt für Wein- und Obstbau, Klosterneuburg, Austria.
Department of Viticulture and Oenology, South African Grape and Wine Research Institute, Stellenbosch University, South Africa.
PLoS One. 2021 Jul 22;16(7):e0254919. doi: 10.1371/journal.pone.0254919. eCollection 2021.
Anecdotal evidence suggests that spontaneous alcoholic fermentation of grape juice is becoming a more popular option in global wine production. Wines produced from the same grape juice by inoculation or spontaneous fermentation usually present distinct chemical and sensorial profiles. Inoculation has been associated with more similar end-products, a loss of typicity, and lower aroma complexity, and it has been suggested that this may be linked to suppression of the local or regional wine microbial ecosystems responsible for spontaneous fermentations. However, whether inoculated fermentations of different juices from different regions really end up with a narrower, less diverse chemical profile than those of spontaneously fermented juices has never been properly investigated. To address this question, we used grape juice from three different varieties, Grüner Veltliner (white), Zweigelt (red), and Pinot noir (red), originating from different regions in Austria to compare spontaneous and single active dry yeast strains inoculated fermentations of the same grape samples. The chemical analysis covered primary metabolites such as glycerol, ethanol and organic acids, and volatile secondary metabolites, including more than 40 major and minor esters, as well as higher alcohols and volatile fatty acids, allowing an in depth statistical evaluation of differences between fermentation strategies. The fungal (mainly yeast) communities throughout fermentations were monitored using automated ribosomal intergenic spacer analysis. The data provide evidence that inoculation with single active dry yeast strains limits the diversity of the chemical fingerprints. The fungal community profiles clearly show that inoculation had an effect on fermentation dynamics and resulted in chemically less diverse wines.
有传闻证据表明，葡萄汁的自发酒精发酵在全球葡萄酒生产中越来越受欢迎。用接种或自发发酵的相同葡萄汁生产的葡萄酒通常具有明显不同的化学和感官特征。接种与更相似的终产物、典型性丧失和香气复杂性降低有关，有人认为这可能与抑制负责自发发酵的本地或区域葡萄酒微生物生态系统有关。然而，从未有过适当的调查来确定来自不同地区的不同果汁的接种发酵是否真的会导致比自发发酵果汁更窄、更不多样化的化学特征。为了解决这个问题，我们使用了来自奥地利不同地区的三种不同品种的葡萄汁，即绿维特利纳（白葡萄）、茨威格（红葡萄）和黑皮诺（红葡萄），比较了相同葡萄样品的自发和单一活性干酵母接种发酵。化学分析涵盖了初级代谢物，如甘油、乙醇和有机酸，以及挥发性次级代谢物，包括 40 多种主要和次要酯类，以及高级醇和挥发性脂肪酸，从而可以对发酵策略之间的差异进行深入的统计评估。使用自动核糖体基因间 spacer 分析监测整个发酵过程中的真菌（主要是酵母）群落。数据表明，单一活性干酵母的接种限制了化学指纹的多样性。真菌群落图谱清楚地表明，接种对发酵动力学有影响，导致葡萄酒的化学组成差异较小。
