This study was undertaken to reveal the correlation between the taste quality and bacterial community of Dazhu rice wine. Taste attributes were measured using an electronic tongue, the types and contents of organic acids and amino acids were analyzed, and lactic acid bacteria were isolated and identified from the rice wine. Moreover, analysis and functional prediction of its bacterial community were carried out using MiSeq high-throughput sequencing technology. Finally, the correlation between various taste attributes and bacterial community was calculated. The results showed that Dazhu rice wine varied widely in terms of saltiness, sourness and bitterness. The rice wine contained seven organic acids and 15 amino acids, the predominant organic acids being lactic acid (8.82 mg/g) and acetic acid (6.27 mg/g), and the predominant amino acids being glutamic acid (8.06 mg/g), leucine (4.10 mg/g) and aspartic acid (3.94 mg/g). A total of 14 lactic acid bacteria were isolated by pure culture and identified as five species, namely Limosilactobacillus fermentum (four strains), Pediococcus pentosaceus (four strains), Lacticaseibacillus paracasei (two strains), Lactiplantibacillus plantarum (two strains) and Leuconostoc pseudomesenteroides (two strains). High-throughput sequencing results showed that the average relative contents of Firmicutes and Proteobacteria were greater than 1.0%, with a cumulative content of 96.93%; the relative contents of Lactobacillus, Pediococcus, Weissella, Lactococcus, Leuconostoc and Acinetobacter were greater than 1.0%, with a cumulative content of 89.43%. Correlation analysis showed a significant negative correlation (P < 0.05) between Weissella and taste indicators such as aftertaste A, astringency and bitterness. These findings showed that the major organic acids in Dazhu rice wine were lactic acid and acetic acid, that the major amino acids were glutamic acid, leucine and aspartic acid, and that bacterial community was dominated by lactic acid bacteria such as Lactobacillus, Pediococcus and Weissella. Weissella could have a positive significance on the formation of rice wine quality.

The fungal community structure and flavor quality of white, yellow and black high-temperature Daqu from company A in Xiangyang, China were analyzed using MiSeq high-throughput sequencing and electronic nose technology. The sequencing results showed no significant differences in the α-diversity or β-diversity of fungal community among different colored Daqu (P > 0.05); the dominant fungal genera belonged to Ascomycota including Thermomyces (36.50%), Thermoascus (27.15%), Saccharomycopsis (9.23%) and Dipodascus (1.19%), and Mucoromycota including Aspergillus (9.36%), Rhizopus (1.44%) and Rhizomucor (1.03%). The electronic nose exhibited high sensor responses to volatile organic sulfides, terpenoids, hydroxides and ethanol and low sensor responses to aromatic substances in high-temperature Daqu; the Mann-Whitney test revealed significantly higher sensor responses to aromatic substances (P < 0.01) and lower sensor responses to the other aroma components (P < 0.05) in yellow than black Daqu. In addition, based on the fungal sequence data from the MG-RAST database for three different colored high-temperature Daqu produced by company B, comparative analysis of the fungal community structure of high-temperature Daqu produced by companies A and B was carried out. It was found that there were highly significant differences (P < 0.01) in the α-diversity and β-diversity of fungal community between Daqu produced by the two companies, and the results of cluster analysis showed that the Mahalanobis distance between the different colored high-temperature Daqu from the same company was closer. Finally, in this study, four strains of S. fibuligera were isolated from high-temperature Daqu produced by company A by traditional pure culture method. In conclusion, there was a significant difference between the fungal communities of high-temperature Daqu produced by companies A and B, which was greater than the difference between different colored high-temperature Daqu produced by the same company.