Canonico Laura, Comitini Francesca, Oro Lucia, Ciani Maurizio
Dipartimento Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche Ancona, Italy.
Front Microbiol. 2016 Mar 11;7:278. doi: 10.3389/fmicb.2016.00278. eCollection 2016.
The average ethanol content of wine has increased over the last two decades. This increase was due to consumer preference, and also to climate change that resulted in increased grape maturity at harvest. In the present study, to reduce ethanol content in wine, a microbiological approach was investigated, using immobilized selected strains of non-Saccharomyces yeasts namely Starmerella bombicola, Metschnikowia pulcherrima, Hanseniaspora osmophila, and Hanseniaspora uvarum to start fermentation, followed by inoculation of free Saccharomyces cerevisiae cells. The immobilization procedures, determining high reaction rates, led a feasible sequential inoculation management avoiding possible contamination under actual winemaking. Under these conditions, the immobilized cells metabolized almost 50% of the sugar in 3 days, while S. cerevisiae inoculation completed all of fermentation. The S. bombicola and M. pulcherrima initial fermentations showed the best reductions in the final ethanol content (1.6 and 1.4% v/v, respectively). Resulting wines did not have any negative fermentation products with the exception of H. uvarum sequential fermentation that showed significant amount of ethyl acetate. On the other hand, there were increases in desirable compounds such as glycerol and succinic acid for S. bombicola, geraniol for M. pulcherrima and isoamyl acetate and isoamyl alcohol for H. osmophila sequential fermentations. The overall results indicated that a promising ethanol reduction could be obtained using sequential fermentation of immobilized selected non-Saccharomyces strains. In this way, a suitable timing of second inoculation and an enhancement of analytical profile of wine were obtained.
在过去二十年中，葡萄酒的平均乙醇含量有所增加。这种增加是由于消费者的偏好，以及气候变化导致收获时葡萄成熟度提高。在本研究中，为了降低葡萄酒中的乙醇含量，研究了一种微生物学方法，即使用固定化的选定非酿酒酵母菌株，即博伊丁毕赤酵母、美极梅奇酵母、嗜渗 Hanseniaspora酵母和葡萄汁有孢汉逊酵母开始发酵，随后接种游离的酿酒酵母细胞。固定化程序确定了高反应速率，实现了可行的顺序接种管理，避免了实际酿酒过程中可能的污染。在这些条件下，固定化细胞在3天内代谢了近50%的糖分，而接种酿酒酵母完成了所有发酵。博伊丁毕赤酵母和美极梅奇酵母的初始发酵在最终乙醇含量降低方面表现最佳（分别为1.6%和1.4% v/v）。除葡萄汁有孢汉逊酵母的顺序发酵显示出大量乙酸乙酯外，所得葡萄酒没有任何负面发酵产物。另一方面，对于博伊丁毕赤酵母的顺序发酵，甘油和琥珀酸等理想化合物有所增加；对于美极梅奇酵母，香叶醇有所增加；对于嗜渗 Hanseniaspora酵母的顺序发酵，乙酸异戊酯和异戊醇有所增加。总体结果表明，使用固定化选定非酿酒酵母菌株的顺序发酵可以实现有前景的乙醇降低。通过这种方式，获得了合适的二次接种时间，并改善了葡萄酒的分析概况。
