Yeasts are pivotal brewing microbes that are associated with the flavor and quality of Chinese baijiu, yet research on dominant yeasts in strong-flavor baijiu brewing remains limited. In this study, Saccharomyces cerevisiae, Pichia kudriavzevii, and Kazachstania bulderi were identified as predominated yeasts in strong-flavor baijiu. Each strain showed distinct characteristics in ethanol resistance, thermal tolerance, and lactic acid tolerance, severally. S. cerevisiae FJ1-2 excelled in ethanol and ethyl ester production, P. kudriavzevii FJ1-1 in ethyl acetate, and K. bulderi FJ1-3 in lactic acid generation. Subsequently, the reinforced Fuqu of each yeast were severally prepared for application in baijiu brewing to verify their functions. Results revealed that the relative abundance of fortified yeast in each group rose. Pichia, Kazachstania, and Saccharomyces emerged as the core microbe for each group, respectively, by co-occurrence network analysis, influencing the microbiota to regulate flavor substances. In short, P. kudriavzevii FJ1-1 enhanced ethyl acetate. K. bulderi FJ1-3 improved ethyl caproate production and decreased levels of ethyl acetate and higher alcohols by modulating yeast community between Pichia and Saccharomyces. This is a systematic endeavor to study the functions of yeasts of strong-flavor baijiu, providing a solid basis for improving baijiu quality.

Monascus pigments (MPs) and monacolin K (MK) are important secondary metabolites produced by Monascus spp. This study aimed to investigate the effect of soybean protein isolate (SPI) on the biosynthesis of MPs and MK based on the analysis of physiological indicators, transcriptomes, and metabolomes. The results indicated that the growth, yellow MPs, and MK production of Monascus pilosus MS-1 were significantly enhanced by SPI, which were 8.20, 8.01, and 1.91 times higher than that of the control, respectively. The utilization of a nitrogen source, protease activity, the production and utilization of soluble protein, polypeptides, and free amino acids were also promoted by SPI. The transcriptomic analysis revealed that the genes mokA, mokB, mokC, mokD, mokE, mokI, and mokH which are involved in MK biosynthesis were significantly up-regulated by SPI. Moreover, the glycolysis/gluconeogenesis, pyruvate metabolism, fatty acid degradation, tricarboxylic acid (TCA) cycle, and amino acid metabolism were effectively up-regulated by SPI. The metabolomic analysis indicated that metabolisms of amino acid, lipid, pyruvate, TCA cycle, glycolysis/gluconeogenesis, starch and sucrose, and pentose phosphate pathway were significantly disturbed by SPI. Thus, MPs and MK production promoted by SPI were mainly attributed to the increased biomass, up-regulated gene expression level, and more precursors and energies.

The implementation of innovative techniques to achieve low-salt strategies in cured products is a critical issue faced by the food industry. This study aimed to investigate the impact of ultrasound treatment on the quality of the low-salt air-dried fish. The results showed that compared to traditional liquid curing, ultrasound-assisted curing significantly increased the NaCl transfer rate, improved tenderness, and improved water retention and in vitro digestibility (p < 0.05). Microscopic observations revealed that ultrasound treatment substantially disrupted the muscle fiber structure, enlarging the spaces between fibers. Furthermore, ultrasound-assisted curing led to the unfolding of the spatial structure of myofibrillar proteins, enhanced intermolecular hydrophobic interactions, and promoted protein oxidation (p < 0.05), which are fundamental reasons for the improvement in fish quality. Thus, ultrasound treatment had a positive effect on fish curing, with the optimal parameters identified as 590 W for 78 min. Overall, the findings of this study provide evidence for the application of low-salt processing technology in fish products.

Sauce-flavor Daqu is the solid-state fermentation starter for sauce-flavor Baijiu. Its microbial community influences flavor formation, yet links between community change, process conditions, and flavor development during high-temperature fermentation remain unclear. We investigated Daqu fermentation by integrating high-throughput sequencing, monitoring of physicochemical parameters, and analysis of volatile compounds. Fermentation temperature showed three phases: rapid rise, fluctuating plateau, and gradual decline. High temperatures were associated with increased thermophilic microbes such as Bacillus and Thermoascus and with higher levels of reducing sugars and amino acid nitrogen; amylase, protease, and other hydrolase activities were detected. Bacterial composition varied more than fungal composition; Firmicutes and Ascomycota were the dominant phyla, and Bacillus and Thermoascus were abundant genera. Canonical correspondence analysis associated reducing sugars, acidity, and moisture with early community shifts, and amino acid nitrogen with later shifts; reducing sugars and moisture showed the strongest associations. Filamentous fungi and Bacillus correlated with pyrazine-type compounds. These results link microbial composition, process parameters, and flavor profiles, and may inform the standardization and mechanization of Daqu production.

The distribution, mineralization, and transformation of soil organic phosphorus (P) exhibits strong regional characteristics because of variations in climate and pear varieties in Yanbian apple–pear orchard. Soil samples were collected in 11, 25, 40, and 63-year-old apple-pear orchards, at the depths of 0–20 cm, 20–40 cm, and 40–60 cm. Soil aggregates were sieved using the dry sieving method, and the concentrations of organic P were determined using the improved Bowman-Cole method. Differences in organic P in soil aggregates were analyzed in respect to planting year, soil layer, and season. According to the results, with an increase in planting years, labile, moderately labile, moderately stable, highly stable, and total extracted organic P in soil aggregates increased and then decreased. The concentrations were the lowest in the 11-year-old orchard and the highest in the 25-year-old orchard. With an increase in soil layer depth, all the forms of organic P concentrations in soil aggregates decreased linearly, and there were significant differences among different levels. In addition, with shifting seasons from spring, summer, to autumn, the labile organic P concentrations in soil aggregates decreased gradually, and the moderately labile, highly stable, and total extracted organic P concentrations first increased and then decreased, while the moderately stable ones first decreased and then increased. All the forms of organic P concentrations in soil aggregates were the highest in the <0.25 mm aggregate size fraction, followed by the 0.25–0.5 mm fraction. The concentrations of total extracted organic P decreased with an increase in aggregate size fraction. According to the results, organic P is accumulated relatively easily in smaller aggregates, and moderately labile organic P was the major form of organic P in the apple-pear orchard soil, followed by highly stable organic P.