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.

In this study, we comparatively investigated the emulsifying activity index (EAI) and emulsion stability index (ESI) of camel whey protein (CWP) and bovine whey protein (BWP) at different water/oil phase ratios (8:2, 7:3, 5:5, 3:7, and 2:8). The results showed that with the increase in oil phase volume fraction, the EAI and ESI of both proteins were significantly increased. When oil phase volume fraction was higher than 70%, the emulsions were no longer separated into layers. At the same water/oil phase ratio, the EAI and ESI of Pickering emulsion stabilized with CWP were higher than those with BWP. The Pickering emulsion stabilized by CWP showed smaller droplet size of (722.41 ± 77.91) nm at an oil phase volume fraction of 30%, and the absolute value of the zeta potential was higher than 30 mV ((33.58 ± 0.15) mV) at an oil phase volume fraction of 20%. Compared with BWP Pickering emulsion, the ESI of CWP was improved by about 200%. This study showed that CWP could be used as a high-quality emulsifier to stabilize Pickering emulsions and be applied in the development of functional camel milk food products.

In this study, blended walnut oil (BWO) microcapsules with wall materials consisting of walnut protein isolate (WPI) and gum arabic (GA), sodium alginate (SA) or carboxymethyl cellulose sodium (CMC) were prepared by complex coacervation and freeze drying to improve the oxidative stability of vegetable oils. The optimum ratio of protein to polysaccharide (WPI:GA = 4:1, WPI:SA = 6:1, and WPI:CMC = 6:1) and pH (4.3, 4.3 and 4.4 for WPI combinations with GA, SA, and CMC, respectively) for the preparation of different composite wall materials were determined based on zeta potential and turbidity. The differences in encapsulation efficiency, physicochemical properties, and microscopic morphology of the three types of microcapsules were compared. The microcapsules (WPIGA-BWO) with a WPI:GA ratio of 4:1 at pH 4.3 had the highest encapsulation efficiency (94.02%) and solubility (84.49%) with an average particle size of 226.70 μm. Infrared spectroscopy confirmed that WPI and polysaccharides formed coacervates through electrostatic interactions, which could be used as wall materials for encapsulating blended oils. X-ray diffraction (XRD) analysis showed that the WPIGA-BWO microcapsules had high relative crystallinity (40.27%). Thermogravimetric analysis (TGA) indicated that the microcapsules exhibited good thermal stability below 250 ℃. This study can provide a theoretical reference for the development of powdered walnut oil products and the effective protection of vegetable oils, broadening the application scope of walnut oil in the field of food processing.

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.