降甲醇酵母分离筛选与其混菌发酵对脐橙酒品质的影响

Isolation and Screening of Methanol-reducing Yeast and Impact of Mixed-culture Fermentation on Quality of Navel Orange Wine

摘要:

为提升脐橙酒的安全性与风味品质,降低酒中的甲醇含量,从湖南省崀山地区4种脐橙品种的果园土壤、果皮及自然发酵酒中分离酵母菌株,建立共164株酵母的菌种库;用含外源甲醇的模拟发酵培养基对菌株进行2轮降解甲醇能力的筛选,得到2株具有高甲醇降解能力的本土非酿酒酵母菌株Pichia kluyveri UT002和Metschnikowia pulcherrima U405;将优选菌株应用于真实脐橙汁中与商业酿酒酵母QA23进行混菌发酵。试验结果表明,与空白对照组相比,UT002和U405在模拟发酵培养基中的甲醇降解率分别为34.63%、17.74%。在真实脐橙汁发酵中,2株酵母与QA23的顺序接种发酵在有效降低甲醇含量的同时能提升果酒香气,其中S+M(X)组具有最高的甲醇降解率7.14%,S+P(X)组的挥发性化合物总量和酯类物质含量最高,S+M+P(X)组在闻香评价中整体喜好性最高。

Abstract:

Aiming to improve the safety and flavor quality of navel orange wine and reduce methanol content in fruit wine, yeast strains were isolated from orchard soil, fruit peels, and spontaneously fermented wine of four navel orange varieties in the Langshan area of Hunan Province, establishing a yeast strain library comprising 164 isolates. Using a simulated fermentation system supplemented with exogenous methanol, two rounds of screening for methanol degradation ability were performed, yielding two indigenous non-Saccharomyces yeast strains with high methanol-degrading capability: Pichia kluyveri UT002 and Metschnikowia pulcherrima U405. The selected strains were then used in mixed-culture fermentation with commercial Saccharomyces cerevisiae QA23 in fresh navel orange juice. The results showed that compared with the blank control, UT002 and U405 achieved methanol degradation rates of 34.63% and 17.74%, respectively, in the simulated fermentation system. In the fermentation of fresh navel orange juice, sequential inoculation of these two yeasts with QA23 effectively reduced methanol content while improving the aromatic profile of the wine. Among the trials, the S+M(X) group showed the highest methanol degradation rate (7.14%), the S+P(X) group exhibited the highest total volatile compounds and ester content, and the S+M+P(X) group showed the highest overall preference in the aroma evaluation.