耐低温桑葚果酒用酵母的选育及发酵特性

Isolation and fermentation properties of yeast for low temperature resistant mulberry wines

摘要:

为筛选适合桑葚低温酿造果酒的新型菌株，该研究从桑葚自然发酵液中分离、纯化菌种，以耐低温、产酒精能力为条件分级筛选性能优良的发酵菌株；并对所得菌株进行耐受性分析、以及果酒发酵性能和香气特征分析。研究获得产香性能优良的克鲁维毕赤酵母（Pichia kluyveri）2株（PK-1与PK-2），发酵性能优良的酿酒酵母（Saccharomyces cerevisiae）1株（SC-1）。研究结果表明，3株菌种在16 ℃下生长状况良好，乙醇、高糖及SO2耐受性分别达到15%（V/V）、400 g/L及300 mg/L，并且能够适应pH值低至3的果酒生产环境。发酵试验表明，SC-1组酒精体积分数达到13.26%（V/V）；挥发性香气成分共检测出53种，其中SC-1组发现24种、PK-1组32种、PK-2组31种；SC-1组异戊醇及苯乙醇（m/V）分别达到43.09 μg/mL 和143.66 μg/mL；PK-1与PK – 2组乙酸苯乙酯（m/V）分别达到402.96 μg/mL和421.51 μg/mL，特征香气成分差异显著。SC-1菌株低温条件下发酵性能优良，白兰地香型突出；两PK菌株产酯性能优良，可为混菌发酵果酒构建全新的花果香型主体；所获菌株可为改进果酒香型提供一定的理论依据。

Abstract:

To screen novel strains for low-temperature fermentation of mulberry fruit wine. Fermentation strains with excellent low temperature tolerance and alcohol production performance were isolated from the natural fermentation broth of mulberry fruit. The screened strains were also analysed for tolerance. Fruit wine fermentation performance and aroma characterisation were carried out. Two strains of Pichia kluyveri (PK-1 and PK-2) with excellent aroma production and one strain of Saccharomyces cerevisiae (SC-1) with excellent fermentation performance were obtained. The results showed that the three strains grew well at 16 ℃. The tolerance for ethanol, high sugar and SO2 reached 15% (V/V), 400 g/L and 300 mg/L, respectively. For the general production of fruit wines with pH values > 3, all strains could be adapted. The fermentation tests showed that the SC-1 group reached an alcohol content of 13.26% (V/V). A total of 54 volatile aroma compounds were found in the fermentation, of which 24 were found in the SC-1 group, 32 in the PK-1 group and 31 in the PK-2 group. The isoamyl alcohol and phenylethanol content (m/V) in SC-1 group reached 43.09 μg/mL and 143.66 μg/mL, respectively. Phenethyl acetate (m/V) reached 402.96 μg/mL and 421.51 μg/mL in PK-1 and PK-2 groups, respectively, with significant differences in characteristic aroma components. The SC-1 strains had excellent fermentation performance at low temperatures and outstanding brandy flavour. The two PK strains showed an excellent production of the ester. This could be used to create a new floral and fruity aroma for co-fermented fruit wines. The results of this study will provide a reference and basis for improving fruit wine flavor.