Traditional Qula, a distinctive dairy product from the pastoral areas of the Qinghai-Tibetan Plateau, derives its characteristic flavor primarily from microbial activity during production. To elucidate the relationship between core microorganisms and flavor formation during Qula preparation, this study employed high-throughput sequencing and gas chromatography-mass spectrometry (GC-MS) to analyze microbial diversity and flavor compounds throughout the process. Distinct, stage-specific flavor compounds were identified: fermentation (styrene, 3-hydroxy-2-butanone, myristic acid); hanging (phenethyl acetate, n-nonanoic acid); and sun-drying (n-nonanoic acid, n-decanoic acid, caprylic acid). Microbial diversity analysis revealed stage-specific dominant genera: Acetobacter, Lactobacillus, and Saccharomyces during fermentation; Acetobacter, Lactobacillus, Rhodotorula, Papiliotrema, and Kluyveromyces during hanging; and Leuconostoc, Lactococcus, and Apiotrichum during sun-drying. Furthermore, Spearman correlation analysis identified Lentilactobacillus, Lactococcus, Leuconostoc, Debaryomyces, and Saccharomyces as core functional microorganisms significantly correlated with the formation of characteristic flavor metabolites. These results provide a crucial theoretical basis for optimizing the Qula production process and improving its flavor quality.

This study aims to prepare, purify, and identify novel pancreatic lipase (PL) and cholesterol esterase (CE) inhibitory peptides from yak whey protein (YWHP), and to elucidate their underlying mechanisms of action. Results showed that bromelain effectively hydrolyzed YWHP into smaller peptide fragments. Ultrafiltration of yak whey protein hydrolysates (YWPHs) produced three fractions (>10 kDa, 3-10 kDa, and < 3 kDa). The <3 kDa fraction displayed PL and CE inhibitory activities of 36.34 ± 1.00% and 35.85 ± 0.65%, respectively. Fraction II obtained from Sephadex G-25 exhibited strong inhibition on PL and CE. LC-MS identified three novel PL and CE inhibitory peptides (FDI, ADIF, and FDL).These peptides inhibited lipase activities mainly by occupying the catalytic sites and substrate-binding pockets of PL and CE. All three peptides synthesized via solid-phase peptide synthesis exhibited inhibitory activities against both PL and CE. This study provides a theoretical basis for developing hypolipidemic functional products.

This study aimed to elucidate differences between the commercial starter culture (CK) and traditional starters from different Tibetan regions (Gannan (GN), Qinghai (QH), Tibet (XZ)) in fermenting yak yogurt by physicochemical properties, flavor, and bacterial community. Results indicated acidity, proline, arginine, alanine, and C6:0 contents were significantly higher in the traditional starter culture than CK (P < 0.05). Gas chromatography-ion mobility spectrometry analysis found the traditional starter culture group was dominated by alcohols and esters, whereas CK exhibited richer ketones. Metagenomic analysis revealed Lactobacillus delbrueckii (49.56% in XZ, 24.86% in GN) and Streptococcus spp. (18.30% in CK, 17.21% in QH) as the dominant. Moreover, pH and titratable acidity were primary factors affecting microbial diversity. Meanwhile, glutamic acid modulated ester biosynthesis like ethyl acetate, while C16:0 fatty acids inhibited off-odor ketones such as 2-pentanone. This study offers valuable insights into developing specialized fermentation agents and standardizing the quality of yak yogurt.

Unique transport conditions in Tibetan regions delay the storage of yak milk, particularly during the July-August peak production period at 18 °C, promoting microbial activity and benzoic acid accumulation. This substantially heightens food safety risks associated with consumption. This study used 16S high-throughput sequencing and non-targeted metabolomics to examine the association between benzoic acid content, dominant bacterial genera, and key metabolites. At 0 h of storage (G0), the dominant genera in yak milk were Kaistella, Lactococcus, and Streptococcus. As storage extended to 12 h (G12) and 24 h (G24), Lactococcus emerged as the dominant genus and the key lactic acid bacterium producing endogenous benzoic acid. Metabolomics identified 729 differentially expressed metabolites. Amino acid metabolism is the primary enriched pathway. Myosmine, L-Methionine, L-Phenylalanine, 3-Isochromanone, and Indoline showed strong correlations with Lactococcus. This study provides a theoretical foundation for improving quality control and safety in yak milk production.

This study systematically compared the effects of dietary supplementation with glutamine (Gln) and its precursors, including glutamic acid (GA) and α-ketoglutarate (AKG), on growth performance, serum antioxidant and immune parameters, and multi-region gastrointestinal microbiota in suckling lambs. Forty healthy suckling Hu lambs with similar body weight (7.37 ± 1.18 kg) and age (7 ± 0.8 d) were selected and randomly allocated into four groups (n = 10 per group): a control group (CON, without additive), and three treatment groups (GA, AKG, and Gln), each receiving 2 g per animal per day of the corresponding additive. The experimental period lasted for 42 d. All three additives showed a tendency to increase the final body weight (p = 0.056) and significantly increased the average daily gain (ADG) of lambs (p < 0.05). GA supplementation increased the dry matter intake throughout the entire trial (p < 0.05), whereas the addition of AKG and Gln increased the dry matter intake only during the later period (d 21–42) (p < 0.05). The feed-to-gain ratios did not differ among all groups (p > 0.05). Compared with the CON group, all three treatment groups showed elevated serum activities of catalase, glutathione peroxidase, and total antioxidant capacity, as well as increased IgA and IgG contents (p < 0.05). In addition, malondialdehyde concentration was decreased in all three treatment groups (p < 0.05). Moreover, GA supplementation reduced the ruminal alpha diversity while increasing the abundance of butyrate-producing bacteria (Ruminococcaceae UCG-014) (p < 0.05). All three interventions consistently decreased the abundance of the intestinal pathogen Escherichia-Shigella in the ileum (p < 0.05). Correlation analyses showed that ruminal Treponema 2 abundance was negatively correlated with ADG, whereas jejunal Methylobacterium and ileal [Eubacterium] coprostanoligenes group were positively correlated with final body weight or ADG. In conclusion, glutamine and its precursors play an important role in modulating gastrointestinal bacterial diversity and composition, enhancing antioxidant and immune functions, and improving the growth performance of suckling lambs.

Yak ghee (YG) and crossbred yak ghee (YD), traditional fermented dairy products central to the diet of pastoralists in China's Tibetan regions, are distinguished by their lipid composition, volatile profiles, and microbial communities. Nevertheless, comprehensive assessments of quality variations in yak ghee sourced from distinct milk origins are scarce. This research systematically contrasted YG and YD concerning their lipid constituents, volatile compounds, and microbial populations to delineate the factors contributing to quality heterogeneity. Lipidomics analysis revealed 43 distinct lipids, with seven glycerides identified as potential biomarkers. A total of 22 volatile compounds were detected, and 3-hydroxy-2-butanone was identified as a characteristic constituent. More than 20 microbial taxa were identified, with Lactobacillus and Lactococcus designated as key differential genera. The observed quality disparities were found to correlate with lipid degradation patterns and microbial metabolism, thereby establishing a foundation for breed identification and quality assurance.

This study systematically investigated the synergistic modification effects of electron beam irradiation (EBI) pretreatment combined with enzymatic hydrolysis on corn porous starch. Proton nuclear magnetic resonance (H-1 NMR) and amylose content analysis revealed that the combined treatment significantly altered the molecular structure of starch: the degree of branching was markedly reduced, while the amylose content increased significantly from 27.10 % in native starch to 48.75 % in the EBI-ES-30 kGy sample, confirming that electron beam irradiation promotes molecular chain linearization by cleaving the alpha-1,6 glycosidic bonds in amylopectin. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses further elucidated the structural changes: XRD showed a decrease in relative crystallinity, and the ordered structure ratio (R-1(0)4(7)/(1)(0)(2)(2)) in FTIR decreased from 0.69 to 0.59, indicating disruption of the short-range ordered structure. Scanning electron microscopy (SEM) and specific surface area analysis demonstrated that the treated sample exhibited denser pore distribution, larger pore size, and a higher specific surface area (increasing from 2.37 m(2)/g to 2.98 m(2)/g). These structural optimizations significantly enhanced the adsorption performance of the starch, with the EBI-ES-30 kGy sample showing a 21.90 % increase in water absorption capacity (from 125.62 % to 153.14 %) and a 28.40 % increase in oil absorption capacity (from 110.33 % to 141.65 %). Furthermore, adsorption studies on methylene blue indicated that the adsorption process followed the pseudo-second-order kinetic model (R-2 > 0.99), and the isothermal adsorption behavior was highly consistent with the Langmuir model (R-2 > 0.99), achieving a maximum adsorption capacity of 951.10 mg/g. This study confirms that the synergistic effect of EBI and enzymatic treatment provides a novel strategy for the efficient construction of functional porous starch materials.

Iron fortification via oral iron supplementation is a common strategy to alleviate iron deficiency. However, its efficiency is limited by poor palatability and adverse side effects. Consequently, encapsulating iron sources in starch-based carriers is an effective strategy for iron-fortified foods. In this study, ferrous gluconate (FG) or ferric citrate (FC) was incorporated into rice starch, with the starch‑iron salt complexes generated via ultra‑high pressure (UHP) treatment (200, 400 and 500 MPa) or hydrothermal treatment (H). The morphological and physicochemical characteristics and in vitro digestive properties of the resulting complexes were assessed. Overall, the findings showed that iron incorporation markedly enhanced particle size, hydration ability, solubility, swelling capacity and syneresis of the modified rice starch, with the values following the order: H-FG > 500 MPa-FG > 400 MPa-FG > 200 MPa-FG. In contrast, the incorporation of iron salts reduced the elastic modulus (G′), viscous modulus (G″), viscosity and resistant starch (RS) proportion of the starch. Starch-iron salt complexes exhibited favorable processability with typical shear-thinning behavior and tunable freeze-thaw stability, and held promising application potential as iron fortifiers in cereal staples, sauces and frozen foods. Collectively, these findings offer a theoretical basis for the development of iron-fortified functional foods as ingredients.

Zhaiji millet vinegar (ZJMV) is a traditional grain-fermented condiment whose quality improvement is associated with aging time. This study revealed the evolution of physicochemical properties and whole-component of ZJMVs aging 2 to 10 years. Results demonstrated pH, chroma, and the content of total acid, reducing sugar, and amino acid nitrogen fluctuate dynamically, while antioxidant activities were significantly correlated with the content of total flavonoids, total phenols, tetramethylpyrazine, amino acids, and organic acids (p < 0.05). GC-IMS and metabolomics identified 47 volatile organic compounds (VOCs) and 6530 metabolites, with 6 differential VOCs and 19 differential metabolites (p < 0.05, variable importance in projection (VIP) > 1, fold change (FC) < 0.5 or > 2) being shared aging markers. KEGG pathway analysis indicated amino acid metabolism enriched the most differential metabolites, whereas biosynthesis of various alkaloids was critical. Our findings provide novel mechanistic insights into the quality development of ZJMV during aging.

Previous studies demonstrated chitosan's ability to inhibit free fatty acid (FFA) release in emulsions, yet its structural impacts (molecular weight, MW; deacetylation degree, DD) on lipid digestion remained unclear. This study systematically evaluated chitosan variants (MW: 3.2-670 kDa; DD: 71.2-92.5 %) under simulated gastrointestinal conditions. The results revealed that all chitosan formulations suppressed corn oil digestion to varying degrees. Notably, high molecular weight chitosan (670 kDa) with elevated DD (90 %) exhibited the strongest inhibitory activity, reducing the FFA release rate by approximately 77 %. Mechanistically, this resulted from severe emulsion flocculation limiting enzyme access, coupled with enhanced bile salt adsorption (30 % binding) and lipolysis suppression (57 % inhibition). These findings highlight MW/DD as critical determinants of chitosan's lipid-modulating efficacy, offering a strategic basis for designing functional foods targeting controlled nutrient delivery or reduced caloric uptake.

This study investigated the effect of electron beam irradiation (EBI) at doses of 5, 10, 20, and 30 KGy on rice starch and its impact on the Pickering emulsion properties of starch-zein nanocomposites prepared by anti-solvent precipitation. The results showed that EBI treatment reduced the degree of starch branching, thereby enhancing starch-zein interactions. The 10 KGy-irradiated starch-zein nanocomposites (10 KGy-zein) showed the strongest hydrophobicity (contact angle: 75.96°), the smallest nanocomposite size (105.19 nm), the highest emulsifying capacity (100 %), and the best emulsifying stability. Moreover, probiotics encapsulated in emulsions stabilized by the 10 KGy-zein nanocomposites showed enhanced gastrointestinal survival (4.72 log CFU/mL vs. 0 in free cells), achieving effective intestinal-targeted delivery. These findings demonstrate that EBI-treated starch-zein nanocomposites enhance emulsification performance and enable targeted probiotic delivery, showing great potential for gut-focused food applications.

The correlation between flavor profiles and microbial communities in Jiang-shui, a traditional fermented vegetable product from Northwest China, remains incompletely understood. To address this research gap, we analyzed Jiang-shui samples from three regions in Gansu Province (Dingxi, Lanzhou, and Tianshui). Flavor compounds were characterized using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS), revealing 44, 27, and 32 compounds in Dingxi, Lanzhou, and Tianshui samples, respectively. Distinct regional flavor profiles were observed: Dingxi samples exhibited a higher abundance of hydrocarbons, Lanzhou samples were rich in alcohols, and Tianshui samples contained more acids. Concurrently, high-throughput sequencing (HTS) analysis demonstrated significantly greater microbial richness and diversity in Tianshui Jiang-shui compared to samples from Lanzhou and Dingxi (p < 0.05). UPGMA (Unweighted Pair Group Method with Arithmetic Mean) clustering confirmed significant regional differences in microbial composition. LEfSe (Linear Discriminant Analysis Effect Size) analysis identified 17 significantly differential bacterial taxa among the regions. Notably, the relative abundance of Acetobacter showed a strong positive correlation with the flavor compounds (Z)-3-Hexen-1-ol and (E)-3-hexenoic acid (p < 0.01). These results demonstrate that Jiang-shui from different regions of Gansu possesses distinct flavor profiles and microbial communities. Crucially, this study establishes a clear correlation between these factors, addressing a key research gap and providing insights into the regional characteristics and quality formation mechanisms of Jiang-shui.

Fish gelatin hydrogels are typically characterized by weak texture and poor thermal stability. To address this issue, fish gelatin (FG) was modified using kappa-carrageenan (kappa C) and transglutaminase (TG). FG-kappa C, FG-TG, and FG-kappa C-TG gels were prepared. The results demonstrated that the particle size and textural properties of FG gels were significantly enhanced by kappa C and kappa C-TG composite modifications, and their zeta potential was reduced (P < 0.05). As opposed to that, the improvement effects of TG modification were weaker. The highest particle size and hardness, along with the lowest zeta potential, were exhibited by the FG-kappa C-TG(0.06%) gel. Additionally, the FG-kappa C-TG gel system possessed higher apparent viscosity and elastic storage modulus. Fluorescence spectroscopy and UV absorption analysis indicated that fluorescence intensity was reduced by all three modification methods, and the conformational structure of FG was altered to varying degrees. Microstructure, FTIR, and XRD results revealed that the number of hydrogen bonds and isopeptide bonds in the composite gel systems was increased by kappa C and kappa C-TG modifications, enhancing the stability and orderliness of the gel's helical structure, and forming larger aggregates and denser network structures. Furthermore, due to the presence of covalent cross-linking, improved thermal stability was exhibited by the modified gelatin hydrogels. This study not only provides theoretical support for enhancing the performance of fish gelatin but also facilitates the application of modified fish gelatin in improving the sensory quality and flavor characteristics of food, as well as in serving as a matrix material in the biomedical field.

Saturated fatty acids with different chain lengths, namely lauric acid (LA), myristic acid (MA), palmitic acid (PA), and stearic acid (SA) were complexed with rice starch using ultra-high pressure (UHP, 400, or 500 MPa) or heat gelatinization. The microstructure and emulsifying properties of the resulting starch-lipid complexes were analyzed. Compared with controls (starch treated without fatty acid), complexation with fatty acids increased the hydrophobicity of the starch, decreased its average particle size, significantly improved its viscoelasticity and decreased its gelatinization temperature. The emulsion indices of the starch-lipid complexes were determined. Addition of MA treated at 400 MPa (400 MPa-MA) significantly improved the emulsifying capacity of the starch for Pickering emulsions, the relative occluded volume (ROV) reaching 91.22%, markedly higher than the other complexes. The particle size of 400 MPa-MA was significantly smaller than that of the other complexes; the D [4, 3] particle size was 5.08 mu m and the contact angle was 65.18 degrees. Light microscopy showed that the Pickering emulsion stabilized with 400 MPa-MA had a dense network structure, which was more stable than those of the other complexes. The formation and physicochemical properties of starch-lipid complexes appear to be closely related to the preparation method, and ultra-high pressure treatment appears to be an effective approach to prepare starch-lipid complexes for the stabilization of Pickering emulsions.

There is a lack of research on the effects of amino acid starch interaction on the functional properties of products during Ultra-high pressure (UHP) processing. The functional properties of rice starch with the addition of Glu, Ala and Lys were studied under UHP processing. At 400 MPa, all amino acids reduced G ' and weakened the gel strength, and the gel strength order was as follows: Control > Ala > Glu > Lys. At 500 MPa, Glu increased G ' and G '', and enhanced the strength of the gel, but the addition of Lys had the opposite effects, the gel strength order was as follows: Glu > Ala > Control > Lys. With the increased of treatment pressure and time, the G ' and G '' of all samples treated at 500 MPa decreased, and the gel strength weakened. This study will expand the application scope of rice starch as food gelling agents and functional food.

Effective selenium supplementation strategies are essential for alleviating global selenium deficiency. This study utilized the high-selenium-tolerant strain Lactiplantibacillus plantarum NML21 to produce selenium-enriched yogurt, successfully converting inorganic Se(IV) into organic selenium, with selenoproteins accounting for 69.52 % of the total selenium content (995.19 +/- 68.60 mu g/g). Selenium-enriched yogurt exhibited excellent physicochemical properties and antioxidant activity. Volatile flavor analysis identified 36 compounds, with NML21 and SeNML21 significantly enhancing ketone flavors in yogurt, particularly increasing the contents of 2heptanone and 2,3-pentanedione. Untargeted metabolomics identified 215 non-volatile metabolites, with NML21 and SeNML21 significantly regulating key metabolic pathways, including the phosphotransferase system, ABC transporters, and amino acid biosynthesis, promoting the accumulation of beneficial metabolites. Selenium specifically influenced the biosynthesis pathways of ABC transporters, phenylalanine, tyrosine, and tryptophan. This study demonstrates that NML21 is a promising strain for producing selenium-enriched functional yogurt, offering innovative perspectives for dietary selenium supplementation and functional food development.

Microbial fermentation, as a green and efficient starch modification technology, shows great potential in optimizing the functional properties of starch. In this study, Lactiplantibacillus plantarum L1 and Pichia kudriavzevii K1 were isolated from traditional Chinese fermented food Jiangshui and employed to ferment quinoa starch. Both strains induced common modifications including surface erosion, significantly increased solubility, reduced swelling power and gel strength, and markedly improved starch digestibility by increasing the content of rapidly digestible starch (RDS) and decreasing the content of resistant starch (RS). Specifically, the RDS content increased from 64.92 % to 69.62 %, while the RS content decreased from 17.81 % to 12.73 % under the same condition. Notably, the two strains regulated the starch properties through distinct mechanisms. L. plantarum L1 fermentation was more effective in reducing starch granular size and branching degree, leading to a substantial enhancement in oil-holding capacity (increased by 38.57 %). In contrast, P. kudriavzevii K1 fermentation significantly enhanced the water-holding capacity (increased by 33.80 %) and solubility (increased by 21.91 %), which was associated with its pronounced effect on improving the short-range molecular order. This research can lay a foundation for the development and application of microbial resources for starch fermentation modification.