In this study, the effects of extrusion combined with cellulase on the structural, physicochemical, and functional properties of bamboo shoots dietary fiber were evaluated. Extrusion-cellulase treatment increased the contents of soluble dietary fiber (22.17 g/100 g dry solids). The scanning electron microscopy and Fourier transformed infrared spectroscopy analyses showed that the extrusion-cellulase treatment altered the structure of bamboo shoots dietary fiber without destroying the main components. Bamboo shoots dietary fiber modified by extrusion-cellulase treatment showed improved water-holding capacity (9.34 g/g dry solids), oil-holding capacity (10.74 g/g dry solids), swelling capacity (8.32 mL/g dry solids), cation exchange capacity and functional properties, including glucose adsorption capacity (158 mg/g dry solids), cholesterol adsorption capacity (9.8 mg/g dry solids (pH 2), and 11.4 mg/g dry solids (pH 7)), and nitrite ion adsorption capacity (29 μg/g dry solids (pH 2) and 21 μg/g dry solids (pH 7)). This experiment provided a theoretical basis for the modification of bamboo shoots dietary fiber, and the bamboo shoots dietary fiber modified by extrusion-cellulase can be useful as a fiber-rich ingredient in functional foods.

The Chishui River basin is the main production area of the sauce-flavor Baijiu. Due to the particularity of sauce-flavor Baijiu technology, a large site of workshops needs to be built for brewing and storage. Therefore, used the natural karst caves of Guizhou province to manufacture the sauce-flavor Baijiu, which has enriched the connotation of sauce-flavor Baijiu and saved valuable land resources. In this study, the fermentation grains in the seven stages during the Xiasha round of the cave-brewed sauce-flavor Baijiu (CBSB) were detected using a combination of physicochemical analysis, Headspace solid-phase microextraction gas chromatography-mass detection, and Illumina HiSeq sequencing methods. The results showed Unspecified_Leuconostocaceae, Weissella, Unspecified_Bacillaceae, Saccharomycopsis, Thermomyces, and Unspecified_Phaffomycetaceae were the main bacterial and fungal genera in the stacking fermentation (SF). In the cellar fermentation (CF), the Lactobacillus, Unspecified_Lactobacillaceae, Thermoactinomyces, Saccharomycopsis, Unspecified_Phaffomycetaceae, and Wickerhamomyces were the main bacterial and fungal genera. A total of 72 volatiles were detected in the fermented grains. Linear discriminant analysis Effect Size (LEfSe) identified 23 significantly different volatile metabolites in the fermentation process, including 7 esters, 6 alcohols, 4 acids, 3 phenols, 1 hydrocarbon, and 2 other compounds. Redundancy analysis was used to explore the correlation between dominant microbial genera and physicochemical properties. Starch was the main physicochemical property affecting microbial succession in the SF. Acidity, moisture, and reducing sugar were the main driving factors of microbial succession in the CF. The Pearson correlation coefficient revealed the correlation between dominant microbial genera and significantly different volatile flavor substances. A total of 18 dominant microbial genera were associated with significantly different volatile metabolites, Lactobacillus, Weissella, Wickerhamomyces, and Aspergillus were shown to play crucial roles in metabolite synthesis. On this basis, a metabolic map of the dominant microbial genera was established. This study provides a theoretical basis for the production and quality control of sauce-flavor Baijiu brewed in natural karst caves and lays a foundation for studying the link between flavor formation and microorganisms.

Xiaoqu, one of three traditional jiuqu in China, is a saccharifying and fermenting agent used in Xiaoqu jiu brewing, with different ingredient compositions and preparation techniques used in various regions. The yield and quality of Xiaoqu jiu are significantly affected by the metabolites and microbiota of Xiaoqu; however, the associated relationship remains poorly understood. This study aimed to analyze this relationship in three typical traditional Xiaoqu from the Guizhou province in China. The non-volatile metabolites of Xiaoqu were detected using gas chromatography time-of-flight mass spectrometry, whereas the classification and metabolic potential of the microbiota were investigated using metagenomic sequencing. Results show that Firmicutes, Proteobacteria, and Actinobacteria represent the dominant bacterial phyla, with Lactobacillus, Bacillus, Acinetobacter, Leuconostoc, and Weissella found to be the dominant bacterial genera. Meanwhile, Ascomycota, Mucoromycota, and Basidiomycota are the dominant fungal phyla with Aspergillus, Saccharomyces, Pichia, Rhizopus, and Phycomyces being the predominant fungal genera. Functional annotation of the microbiota revealed a major association with metabolism of carbohydrates, cofactors, and vitamins, as well as amino acids. A total of 39 significantly different metabolites (SDMs) were identified that are involved in 47 metabolic pathways, primarily that of starch and sucrose; glycine, serine, and threonine; glyoxylate and dicarboxylate; pyruvate; as well as biosynthesis of pantothenate and CoA. Further, based on Spearman's correlation analysis, Aspergillus, Saccharomyces, Lactobacillus, Acetobacter, Weissella, Pantoea, Desmospora, and Bacillus are closely correlated with production of physicochemical indexes and SDMs. Moreover, the metabolic network generated for the breakdown of substrates and formation of SDMs in Xiaoqu was found to primarily center on the metabolism of carbohydrates and the tricarboxylic acid cycle. These results provide insights into the functional microorganisms and metabolic patterns present in traditional Guizhou Xiaoqu and might guide researchers in the production of stable and efficient Xiaoqu in the future.

Pit fermentation is the critical stage for flavor formation in sauce-flavored Baijiu (SFB). This study aimed to elucidate the fermentation characteristics in fermented grains at the start (EP) and at the end (OP) of pit fermentation across seven rounds of SFB. Kroppenstedtia and Issatchenkia gradually replaced Pseudomonas and Pichia in EP, while Lactobacillus and Issatchenkia maintained dominance in OP. In both groups, volatile flavor compounds (VFCs) and moisture contents initially increased and then declined, non-volatile flavor compounds (N-VFCs) and starch contents overall decreased, and acidity, reducing sugar, and organic acid levels generally increased. Additionally, the VFC and N-VFC contents consistently increased from EP to OP within each round. Correlation analysis revealed Issatchenkia, Kroppenstedtia, Monascus, Virgibacillus, and Pichia significantly contributed to flavor compound. Finally, a metabolic network was constructed to predict microbial and flavor compound metabolic pathways. This study provided insights into the fermentation characteristics of SFB from a multi-dimensional perspective.