Comparison of Microbial Communities and Volatile Profiles of the Wines Made from Mulberry and Grape

In this study, three kinds of wines separately made from mulberry (MW), grape (GW), or mulberry/grape (MGW) were developed and their enological parameters, sensory scores, volatile components, and microbiota were investigated and compared. Contrary to the order of residue sugar and acidity of the three kinds of wines, the order of alcohol content from high to low is GW, MW and MGW. A total of 60 volatile components (VCs), including esters (17), alcohols (12), acids (6), aldehydes (7), ketones (3), alkenes (3), amines (3), alkanes (4), pyrazines (2), benzene (1), sulfide (1), and thiazole (1), were identified by GC-IMS. The fingerprint of VCs and principal component analysis revealed that the volatile profiles of MGW and GW were more similar in comparison to that of MW and were significantly correlated with the mass ratio of mulberry to grape. Lactobacillus, Weissella, Pantoea, Leuconostoc, Lactococcus, Paenibacillus, Pediococcus, and Saccharomyces were identified as the main microflora at genus level shared by the MW, MGW, and GW, suggesting the heterolactic bacteria may contribute more to the high content of volatile acids in MW and MGW. The heatmap of core microbiota and main VCs of MW, MGW, and GW suggested the complicated and significant correlation between them. The above data implied that the volatile profiles were more closely related to the raw materials of winemaking and markedly affected by the fermentation microorganisms. This study provides references for evaluation and characterization of MGW and MW and improvement of MGW and MW wine making process.

本研究开发了三款葡萄酒，分别以桑葚酒（mulberry wine, MW）、葡萄酒（grape wine, GW）以及桑葚-葡萄混合酒（mulberry/grape wine, MGW）为原料酿制而成，并对其酿酒学参数、感官评分、挥发性成分（VCs）以及微生物群落开展了探究与对比分析。相较于三款葡萄酒的残糖与酸度排序，其酒精度由高到低依次为GW、MW与MGW。本研究通过气相色谱-离子迁移谱（GC-IMS）共鉴定出60种挥发性成分（VCs），包括酯类（17种）、醇类（12种）、酸类（6种）、醛类（7种）、酮类（3种）、烯烃类（3种）、胺类（3种）、烷烃类（4种）、吡嗪类（2种）、苯类（1种）、硫化物（1种）以及噻唑类（1种）。挥发性成分指纹图谱与主成分分析结果显示，混合酒（MGW）与葡萄酒（GW）的挥发性成分谱相较于桑葚酒（MW）更为相似，且该特征与桑葚与葡萄的原料质量比显著相关。在属水平上，乳杆菌属（Lactobacillus）、魏斯氏菌属（Weissella）、泛菌属（Pantoea）、明串珠菌属（Leuconostoc）、乳球菌属（Lactococcus）、类芽孢杆菌属（Paenibacillus）、片球菌属（Pediococcus）以及酵母菌属（Saccharomyces）被鉴定为三款葡萄酒共有的核心微生物群落，这提示异型乳酸发酵细菌可能对桑葚酒（MW）与混合酒（MGW）中高含量的挥发性酸贡献更大。针对三款葡萄酒的核心微生物群与主要挥发性成分所构建的热图显示，二者间存在复杂且显著的相关性。上述研究数据表明，葡萄酒的挥发性成分谱与酿酒原料的关联更为紧密，同时也显著受发酵微生物的影响。本研究可为混合酒（MGW）与桑葚酒（MW）的品质评价、特征解析以及其酿造工艺的优化提供参考依据。