This study isolated 13 strains of lactic acid bacteria (LAB) from Xinjiang local fermented foods and evaluated their curdling properties and antioxidant activity. Strains with superior curdling properties and antioxidant activity were selected for Xinjiang cheese production using different processing techniques, followed by untargeted metabolomic analysis. We identified five Lactiplantibacillus plantarum strains, three Pediococcus pentosaceus strains, two Limosilactobacillus fermentum strains, two Lactococcus lactis strains, and one Streptococcus thermophilus strain. All strains exhibited acid and bile salt tolerance. Based on curdling characteristics, sensory scores, and antioxidant activity, four superior strains—JY4, NC1, HM4, and HM6—were selected for cheese production using different processing methods. Untargeted metabolomic analysis of cheese samples showed that carbohydrates and their conjugates, amino acids, peptides and their analogs, and fatty acids and their conjugates were the major categories of differential metabolites. The differential metabolic pathways were primarily concentrated in the biosynthesis of secondary metabolites, lipid metabolism, amino acid metabolism, and carbohydrate metabolism. Plain Xinjiang cheese (YW), Xinjiang cheese supplemented with goji berry powder after fermentation (TJ), and Xinjiang cheese supplemented with goji berry powder before fermentation (HH) exhibited better flavor and nutritional value compared with commercial plain Xinjiang cheese (SY). Specifically, YW exhibited the best flavor quality, TJ showed more pronounced probiotic properties due to the addition of goji berries, while HH showed the best comprehensive performance in nutritional value and probiotic functionality. This study helps to enrich microbial resources and deepen the understanding of metabolites in Xinjiang cheese.

Our aim was to investigate the impacts of different raw materials on the microbial diversity in traditional fermented sour porridge and the physiological characteristics of strains isolated from it. Five lactic acid bacterial (LAB) strains (SXZ 6, SZ 2, SZ 4, SMF 3 and SXZ 7) and three yeast strains (SXZ 9, SZ 1+ and SMF 5) were isolated by conventional methods from three fermented sour porridges collected from Qingshuihe County, Inner Mongolia for analysis by high-throughput sequencing. The results indicated that the predominant bacterial genera were Lactobacillus, Acetobacter and Lentilactobacillus, and the dominant fungal genera were Issatchenkia, Alternaria and Pichia. Physiological characterization revealed that after 48 h incubation, all LAB strains reduced the pH to 3.66–3.70. Strain SMF 5 exhibited outstanding gas production performance, SXZ 6 and SZ 1+ exhibited good acid tolerance, and SZ 4 and SMF 5 showed good bile salt tolerance. Additionally, strains SXZ 7 and SXZ 9 scavenged 91.78% and 93.6% of 1,1-diphenyl-2-picrylhydrazyl radical, respectively, while no significant difference was observed in their superoxide anion scavenging capacity. Overall, these results indicated that different raw materials significantly influenced the microbial community structure and functionality in sour porridge, with different cereal combinations specifically promoting bacterial or fungal aggregation. All isolates had good physiological properties, showing great potential for application in food fermentation.

The bacterial diversity and metabolomic characteristics of yogurt from three different producers in Bole, Xinjiang were analyzed by using Illumina sequencing and untargeted metabolomics, and the relationship between them was explored. Bacterial diversity analysis showed that the major bacterial genera in the yogurt samples were Lactobacillus, Klebsiella, Lactococcus, and Acetobacter. Using linear discriminant analysis effect size (LEfSe) and phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt), Lactobacillus, Klebsiella, and Lactococcus were identified as biomarkers, and their functions were predicted. The metabolomic analysis identified a total of 397 metabolites in the positive ion mode and 324 metabolites in the negative ion mode, with lipids and lipid-like substances, organic acids and their derivatives, and organic heterocyclic compounds being the predominant ones. Notably, lipids and lipid-like substances, organic acids and their derivatives were the major differential metabolites, contributing to the flavor of yogurt. The metabolic pathway analysis revealed amino acid metabolism and secondary metabolism to be the main enriched pathways, which aligned partially with the functional prediction results. Integrated microbiomic and metabolomic analyses showed that the genera Lactobacillus, Limosilactobacillus, Lactococcus, and Klebsiella were significantly correlated with some metabolites such as organic acids and their derivatives, as well as lipids and lipid-like substances, indicating that the microbial community affected the nutrients of yogurt through its metabolic activities. This study provides a scientific theoretical basis for the production and quality improvement of Xinjiang yogurt.