Correlational Analysis of the Physicochemical Indexes, Volatile Flavor Components, and Microbial Communities of High-Temperature Daqu in the Northern Region of China

Effect of Wheat Varieties and Cultivation Environments on Grain Endophytes, Microbial Communities, and Quality of Medium-High Temperature Daqu in Chinese Baijiu

Wheat grain serves as the primary raw material for producing medium-high temperature (MT)-Daqu, a fermentation starter crucial for Chinese Baijiu production, characterized by spontaneous fermentation without the inoculation of exogenous substances. However, the interactions among wheat varieties, cultivation environments, and the resulting Daqu quality remain poorly understood. This study evaluates three wheat varieties harvested from three distinct cultivation environments, examining wheat grain quality, grain-associated endophytes, and physicochemical properties and microbial communities of MT-Daqu at 0, 9, and 90 days of fermentation. The results revealed the cultivation environment had the most pronounced impact on wheat fungal endophytes. The physicochemical properties of Daqu were primarily impacted by variety, namely, the enzyme activity impacted by environmental factors. Pantoea, Aspergillus, and Stephylium are key microbial genera shared between wheat grains and MT-Daqu. Redundancy analysis highlighted the critical roles of moisture content, starch content, and amino acid nitrogen levels in driving microbial succession in Daqu. Mantel analysis demonstrated significant correlations between the abundance of dominant fungal endophytes in wheat grains and Daqu quality parameters, including starch content (r = 0.45; p < 0.01), saccharifying activity (r = 0.41), liquefying activity (r = 0.31), and esterifying activity (r = 0.30) (p < 0.05). Spearman correlation analysis indicated that Nesterenkonia, Aspergillus, Cryptococcus, Dioszegia, Golubevia, Udeniomyces and Stemphylium are the dominant wheat-derived bacterial genera associated with the abundance of microorganisms in MT-Daqu. This study elucidated the "cultivation environment-grain endophyte-Daqu microorganism" microbial transmission pathway, providing a theoretical foundation for breeding wheat varieties optimized for Daqu production and identifying suitable production regions.

Revealing the Differences in Microbial Community and Quality of High-Temperature Daqu in the Southern Sichuan-Northern Guizhou Region

High-temperature Daqu is crucial to Jiang-flavor Baijiu production in the Southern Sichuan-Northern Guizhou region of China. However, the complex interplay among microorganisms, enzymes, and metabolites in the Daqu from this region requires further investigation. This study compared four high-temperature Daqu samples from this region, analyzing their physicochemical properties, enzyme activities, volatile compounds, and microbial community composition and function, and exploring the influence of microorganisms on the saccharification and aroma-formation function of Daqu in combination with correlation analysis. The microbial communities in the Daqu samples exhibited functional redundancy, with Desmospora sp. 8437 being consistently dominant (3.6-7.3%). Members of the family Bacillaceae were the principal factors contributing to the differences in starch degradation capacity, protein degradation capacity, and pyrazine content among the Daqu samples, mainly through the amylases and proteases they produce. Kroppenstedtia spp. were principal factors causing the differences in aldehyde and ketone contents, primarily via the lipid degradation enzymes they synthesize. Overall, the bacterial community composition of Daqu greatly influenced its characteristics. This study provided a theoretical basis for understanding the diversity of high-temperature Daqu in the Southern Sichuan-Northern Guizhou region.

Characterization and Correlation Analysis of Bacterial Composition and Physicochemical Quality in High- and Medium-Temperature Daqu from China's Binzhou Region

To investigate the bacterial community structure and physicochemical characteristics of different types of Daqu in the Binzhou region, this study employed traditional pure culture methods, high-throughput sequencing technology, and conventional physicochemical assays for analysis. The research results indicate that Enterococcus faecium and Bacillus licheniformis emerged as the main LAB and Bacillus species in Daqu from Binzhou region, respectively. In addition, high-throughput sequencing revealed significant differences in bacterial community structure between the two types of Daqu (P < 0.01). Compostibacillus and Sebaldella were identified as the biomarkers and potential key strains of high- and medium-temperature Daqu, respectively, and high-temperature Daqu demonstrated higher microbial complexity and stability than medium-temperature Daqu. Physicochemical assays demonstrated that the a* value, Daqu skin hardness, Daqu core hardness, density, starch content, and aminophenol content being significantly higher in high-temperature Daqu (P < 0.05), meanwhile, the L* value, water activity, water content, protein content, liquefaction power, and saccharification power were found to be significantly lower in high-temperature Daqu (P < 0.05). And there was significant association between dominant genera and the physicochemical indexes of Daqu (P = 0.001). It can thus be seen that there were significant differences between the microbial communities and physicochemical indicators of different types of Daqu in the Binzhou region. The results of this study are of great significance for further analyzing the differences between different types of Daqu and improving their quality.

Bacterial composition and physicochemical characteristics of sorghum based on environmental factors in different regions of China

The fermentation process for Jiang-flavored baijiu using sorghum as the raw material involves a variety of microorganisms. However, the specific physicochemical characteristics of sorghum and microbial composition on its surface have not been fully elucidated. We aimed to perform a comprehensive comparative analysis of the variations in physicochemical properties and surface microflora in waxy sorghum samples from three prominent production regions in China (Renhuai, Jinsha, and Duyun). Multivariate statistical assessments were conducted that incorporated local soil and climate variables. The results showed that Cyanobacteria, unclassified bacteria, Proteobacteria, Firmicutes, and Bacteroidota were the dominant bacteria in these regions. These bacteria were associated with ethyl acetate, ethyl caprylate, ethyl lactate, and butyl groups, which synergistically produce flavorful compounds. The surface bacterial communities were affected by soil total phosphorus, altitude, diurnal temperature range, monthly mean temperature, precipitation, and effective accumulated temperature. The findings of this study provide a new perspective on microorganisms related to Jiang-flavored baijiu and can help establish a reference for the stability of liquor quality.

Comparative analysis of bacterial community structure and physicochemical quality in high-temperature Daqu of different colors in Qingzhou production area

To compare the effects of differences in Daqu making technology and production regions on the bacterial composition and physicochemical properties of high-temperature Daqu (HTD), this study analyzed the bacterial community structure of three colors of HTD in the Qingzhou production area and measured their physicochemical quality. At the same time, a comparative analysis was conducted on the bacterial composition of Qingzhou and Xiangyang regions. The results revealed that the HTD in the Qingzhou area exhibited a diverse bacterial community dominated by Lentibacillus, Scopulibacillus, and Staphylococcus. The black HTD displayed the lowest bacterial richness (P < 0.05) and a relatively unique microbial structure. Significant variations were observed in the physicochemical qualities of the three colors of HTD. Notably, white HTD demonstrated higher moisture and ash content, saccharification and liquor-producing power. Yellow HTD exhibited higher amino nitrogen and protein content, and black HTD displayed higher water activity, acidity, and starch content. The variation in Bacillus, Limosilactobacillus, and Weissella distributions across different colors of HTD primarily contributed to these findings. From the HTD samples in the Qingzhou area, Bacillus (61.90 %) and lactic acid bacteria (17.46 %) being the predominant cultivable communities. Cluster analysis identified significant differences in bacterial communities among HTD samples from various production areas. It can enhance the understanding of HTD quality in the Qingzhou area and offer insights for optimizing HTD and Maotai-flavor Baijiu quality.

Preparation of layer-assembled W/O/W-type microencapsulated beads and application in solid-state fermentation

In this study, microcapsule beads-0-3-layers (M-0-3 indicates microencapsulated beads with 0, 1, 2, and 3 layers) were prepared, their properties were measured and characterized, and the effects of M-0-3 on solid-state fermentation were investigated. The results showed that in a liquid environment, the releasing glucoamylase activities of M-0-3 were 55.77%, 47.67%, 45.85%, and 42.87% in 360 h, respectively. In the solid environment, the reducing sugar production efficiency of M-0-3 was 29.84%, 27.72%, 19.16%, and 15.93% in 15 days, respectively. Adding M-0-3 improved the alcohol and reduced sugar content while decreasing the residual starch content of the Jiupei, indicating that adding M-0-3 was beneficial to the solid-state fermentation of Baijiu. Solid-state fermentation simulation experiments illustrated that microcapsule beads play a positive role in the production of Baijiu, enhancing raw material utilization and yield of Baijiu production.

Comparison of the Correlations of Microbial Community and Volatile Compounds between Pit-Mud and Fermented Grains of Compound-Flavor Baijiu

The microbial composition and volatile components of fermented grains (FG) and pit mud (PM) are crucial for the quality and flavor of compound-flavor baijiu (CFB). The physicochemical indices, culturable microorganisms, microbial communities, and volatile components of FG and PM were analyzed and correlated in our research. Considering FG and PM, amplicon sequencing was used to analyze the microbial community and the volatile components were detected by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME). For FG, redundancy analysis and correlation perfume Circos were used to clarify the correlations between the dominant microbial community and volatile components. The results showed that Aspergillus, Pichia, and Rhizopus were the main fungal microflora in FG and PM, whereas Lactobacillus and Bacillus were the dominant bacteria in FG, and Methanosarcina and Clostridium sensu stricto 12 were the dominant bacteria in the PM. The microbial community and volatile compounds in the CB sampled from the bottom layers of the FG were greatly affected by those in the PM. There were 32 common volatile components in CB and PM. For FG, most of the volatile components were highly correlated with Lactobacillus, Bacillus, Aspergillus, Pichia, and Monascus, which includes alcohols, acids and esters. This study reveals correlations between microbial composition, volatile components, and the interplay of FG and PM, which are conducive to optimizing the fermentation process and improving the quality of CFB base.