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.

Purpose: Monascuspigment was widely applied in food processing industry as functional additive, so more attention was paid to the fermentation optimization of pigment production. Therefore, this paper aims to evaluate the best possible fermentative conditions for maximum production of biopigment using submerged fermentation (SFM) and solid state fermentation (SSF) byMonascus purpureusHBSD 08.Design/methodology/approach: The biopigment was produced by using an SMF and an SSF with optimized substrate to achieve higher yield. The antioxidant activity was evaluated by DPPH radical scavenging ability, superoxide anion radical scavenging ability and hydroxyl radical scavenging ability. The pigment composition was analyzed by thin layer chromatography.Findings: MaximumMonascuspigment production (79.6 U/ml and 1,102 U/g) were obtained under an SFM and an SFF. The antioxidant activity of the pigment in an SFM was significantly higher than that in an SFM. The composition of pigment was not different in an SFM and an SFF.Originality/value: The study developed new conditions, andMonascusstrain was a candidate for producing pigment in an SFM and an SFF. To the authors’ best knowledge, this is a first attempt toward comparative evaluation on antioxidant capacity and composition between pigment in an SSF and an SFM. This result will serve forMonascuspigment production.

High-throughput sequencing was used to elucidate the microbial community of strong-flavor Daqu (SFD) (surface and central parts) produced in different Chinese regions, moisture and other six kinds of quality indicators of SFD were detected. In addition, Spearman correlation coefficient was used to identify the relationships between microbial community and quality indicators. In different sample groups of surface and central parts, the differential fungal genus was Alternaria, whereas differential bacteria genera were Weissella, Pediococcus and Leuconostoc. Spearman analysis showed that fungal genera Rhizopus, Stemphylium, and Alternaria were significantly positively correlated with saccharifying ability (p < .01), whereas Rasamsonia was significantly positively correlated with esterification ability (p < .01). Weissella, Pediococcus and Burkholderia were the bacterial genera significantly positively correlated with saccharification ability of SFD samples (p < .01). This study provides a reference for investigating the relationship between microbial community and quality indicators of SFD.