Department of Biotechnology, University of Verona, Villa Lebrecht, Via della Pieve 70, 37029 San Pietro in Cariano, Italy.
J Agric Food Chem. 2020 Nov 25;68(47):13294-13301. doi: 10.1021/acs.jafc.9b08162. Epub 2020 Mar 16.
Terpenes are important contributors to wine aroma. Free and glycosidically bound terpenes are primarily formed in grapes. During fermentation, they undergo important transformation catalyzed by yeast, so that the terpene profile of grape is substantially different from that of the corresponding wine. The present paper assessed the ability of a strain to transform 17 different terpenes. Biotransformation was performed by placing target compounds in incubation with resting cells. Volatile compounds produced were extracted by solid-phase extraction and analyzed by gas chromatography-mass spectrometry. Geranyl acetate, neryl acetate, citronellyl acetate, and menthyl acetate were formed from the corresponding terpene alcohols. β-Citronellol was the main product of geraniol transformation; geranial, an intermediate of this pathway, has also been detected. Limonene was hydroxylated by yeast to form carveol, -2,8-menthadien-1-ol, and -2,8-menthadien-1-ol. Moreover, yeast cells were found to be able to adsorb a significant portion of the terpenes present in the reaction batches, with the extent of this phenomenon being linked to terpene hydrophobicity.
萜类化合物是葡萄酒香气的重要贡献者。游离态和糖苷结合态萜类化合物主要在葡萄中形成。在发酵过程中，酵母催化了重要的转化，使得葡萄中的萜烯图谱与相应葡萄酒的图谱有很大的不同。本文评估了一株酵母菌株转化 17 种不同萜烯的能力。生物转化是通过将目标化合物与静止细胞一起孵育来进行的。通过固相萃取提取产生的挥发性化合物，并通过气相色谱-质谱进行分析。乙酸香叶酯、乙酸橙花酯、乙酸香茅酯和乙酸薄荷酯是从相应的萜烯醇形成的。β-香叶醇转化的主要产物是β-香茅醇；该途径的中间体橙花醛也已被检测到。柠檬烯被酵母羟基化为香芹醇、-2,8-薄荷二烯-1-醇和-2,8-薄荷二烯-1-醇。此外，酵母细胞被发现能够吸附反应批次中存在的很大一部分萜类化合物，这种现象的程度与萜类化合物的疏水性有关。
