酵母菌與乳酸菌共發酵對巨峰葡萄酒風味與化學特性之影響

Abstract

紅酒 (red wine) 是一款歷史悠久且被廣泛飲用的酒精飲品，隨著極端氣候對葡萄熟成與酒質帶來的挑戰，越來越多研究關注微生物作為改善問題的角色。例如近年使用酵母共培養以提升芳香複雜度，然而較少研究探討紅酒中酵母菌與乳酸菌的交互作用，酵母菌發酵中或發酵後的基質很大程度影響後續乳酸菌的發酵，因此本研究旨在評估酵母菌與乳酸菌之接種策略對巨峰葡萄酒化學成分的影響，透過優化紅酒的釀製過程，以提升葡萄酒品質。原料選自台灣果園的巨峰紅葡萄，組成份結果指出冬果有機酸含量明顯高於夏果，特別是蘋果酸濃度可達到2.50 ± 0.27 mg/L，此酸度達乳酸菌啟動發酵的最低閾值，有助於後期的生長與香氣代謝。非釀酒酵母分離自台灣本土葡萄果皮中，Saccharomyces cerevisiae NTUAFM-Gr112 與十株潛在蘋果酸乳酸菌則取自實驗室菌種庫，經篩選後確定實驗菌株以及發酵條件，最後比較順序式與同時蘋果酸乳酸發酵 (malolactic fermentation, MLF) 對巨峰葡萄酒品質影響。實驗結果顯示在酯類香氣分析中，酵母共發酵組 (HP+SC) 可有效提升酯類香氣，其中又以乙酸乙酯 (Ethyl acetate)、癸酸乙酯 (Ethyl decanoate) 與乙酸苯乙酯 (Phenylethyl acetate) 等較為顯著，使得總酯含量與純S. cerevisiae Gr112組 (SC) 相比顯著提升。在MLF組中，則是以乳酸乙酯、丁二酸二乙酯和雙乙醯的濃度有顯著增加，其中又以SIM-MLF表現較佳，這點也在感官品評中的得到驗證，呈現 「花香味」、「黑莓果味」、「奶油味」等描述詞，顯示本研究中SIM-MLF組相較於SEQ-MLF組更能透過MLF發酵提升巨峰葡萄酒的感官特性，可作為提升風味表現與整體感官的有效策略。

Red wine is a historically long-standing alcoholic beverage widely consumed worldwide. With the increasing challenges posed by climate change to grape ripening and wine quality, growing attention has been directed toward the role of microorganisms in improving wine quality. In recent years, mixed yeast fermentations have been applied to enhance aroma complexity; however, limited studies have investigated the interactions between yeasts and lactic acid bacteria (LAB) in red wine. The metabolites produced by yeasts during and after alcoholic fermentation can substantially influence subsequent malolactic fermentation (MLF). Therefore, this study aimed to evaluate the effects of different yeast–LAB inoculation strategies on the chemical composition of Kyoho red wine, with the goal of optimizing the winemaking process and improving wine quality. Kyoho grapes cultivated in Taiwan were used as the raw material. The grape composition analysis indicated a relatively high organic acid content, particularly malic acid, which reached 2.50 ± 0.27 mg/L. This concentration met the minimum requirement for LAB to initiate malolactic fermentation and was beneficial for subsequent aroma development. A non-Saccharomyces yeast isolated from Taiwanese indigenous grapes and Saccharomyces cerevisiae NTUAFM-Gr112, together with ten LAB strains isolated from grapes, were selected from an in-house culture collection. Appropriate strains and fermentation conditions were screened, and the effects of sequential and simultaneous malolactic fermentation on Kyoho red wine quality were evaluated. The results showed that in the aroma compound analysis, the yeast co-fermentation group (HP+SC) significantly enhanced ester formation. Notably, ethyl acetate, ethyl decanoate, and phenylethyl acetate exhibited pronounced increases, with total ester content being 4.21 times higher than that of the pure S. cerevisiae Gr112 fermentation group (SC). In the MLF-treated wines, concentrations of ethyl lactate, diethyl succinate, and isoamyl acetate increased significantly, with the simultaneous malolactic fermentation (SIM-MLF) group showing the most pronounced effects. These chemical changes were consistent with sensory evaluation results, in which the SIM-MLF wines were characterized by descriptors such as “floral,” “blackcurrant,” and “creamy.” Overall, the results demonstrate that SIM-MLF was more effective than sequential malolactic fermentation (SEQ-MLF) in enhancing the sensory characteristics of Kyoho red wine. This strategy represents an effective approach for improving flavor expression and overall sensory quality through malolactic fermentation.