In order to investigate the inhibitory effect of Tricholoma matsutake polysaccharides (TMP) on UVB radiation-induced melanogenesis and the molecular mechanism of melanin synthesis. The study used Tricholoma matsutake as raw material and a new polysaccharide TMP-N was prepared by hot water extraction and DEAE Sepharose Fast Flow purification. The mouse melanoma cells (B16-F10) were utilised as a model to evaluate the effects of TMP-N on melanin content, antioxidant capacity and related gene expression levels after UVB irradiation. The results demonstrated that the molecular weight of TMP-N was 7819.5 Da, mainly composed of glucose, galactose, mannose and fucose. Cellular experimentation demonstrated that the treatment of TMP-N could effectively reduce melanogenesis by inhibiting tyrosinase activity and enhancing the antioxidant capacity of B16-F10 cells. The analysis of the fluorescence quantitative PCR assay demonstrated that TMP-N functioned by downregulating melanogenic pathways through modulation of both PKA and MAPK signalling cascades. This study elucidates the mechanism by which the T. matsutake polysaccharide TMP-N regulates melanin production, providing theoretical support for replacing chemically synthesized photoprotective agents with natural bioactive compounds. The results have significant application value in terms of providing safe and effective protection against UVB radiation damage.

To evaluate the prebiotics of wheat starch-mung bean hull polyphenol complex-based resistant starch (WS-MBPs-R) on the intestinal tract of T2DM patients, this study used the in vitro fermentation model, with wheat starch-based resistant starch (WS-R) and wheat starch-based resistant starch/mung bean skin polyphenols mixture (WS-R/MBPs) as positive controls, to determine the pH, gas production, reducing sugar content and short chain fatty acids (SCFAs) content of the fermentation broth at different times, and analyzed the impact of WS-MBPs-R on the intestinal flora of diabetes patients by 16S rRNA sequencing. Meanwhile, the multi-scale structural changes of WS-MBPs-R during the fermentation process were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The results showed that compared with the negative (without carbon source) and positive control groups, the pH of the fermentation broth in the WS-MBPs-R group significantly decreased to 4.47 after 24 hours of fermentation, while the gas production significantly increased to 8.6 mL (P<0.05). Fermentation with three types of resistant starch promoted the production of SCFAs, especially WS-MBPs-R, whose total SCFAs concentration reached 246.51±3.01 mmol/L after fermentation for 24 h. WS-MBPs-R fermentation could improve the intestinal flora structure of diabetes patients, promote the proliferation of beneficial bacteria such as Prevotella and Bifidobacterium, and inhibit the growth of harmful bacteria such as Escherichia_Shigella and Fusobacterium. After fermentation, the short-range ordered structure and total crystallinity of WS-MBPs-R increased, indicating that gut microbiota preferentially utilized the amorphous region of resistant starch. In conclusion, WS-MBPs-R, a new type of resistant starch, has good probiotics and can be developed and utilized as a functional food raw material for people with diabetes.

Conventional preservation methods such as low temperature and modified atmosphere packaging often target a single preservation requirement. However, these methods cannot address multiple problems such as bacterial growth, enzymatic browning, and loss of flavor during fruit preservation. Consequently, the development of efficient, environment-friendly, and multifunctional preservation technologies was imperative for maintaining fruit quality. In this study, an Fe/Cu metal–organic framework-tartaric acid complex (Fe/Cu MOF-TA) with excellent antibacterial and anti-browning properties was synthesized, which was expected to provide a new, green, and efficient preservation material for fruits. The successful preparation of the Fe/Cu MOF-TA was confirmed using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FT-IR). The antibacterial and anti-browning properties of the Fe/Cu MOF-TA were evaluated through antibacterial experiments and the inhibition rate of polyphenol oxidase. The results demonstrated that, among the five organic acids (citric acid, succinic acid, cinnamic acid, TA, and malic acid), TA exhibited the most significant inhibitory effect on polyphenol oxidase activity. Furthermore, when the concentration ranged from 0 to 1.0 g/L, the polyphenol oxidase activity and degree of browning of the bananas exhibited an inversely proportional relationship with increasing concentrations of TA. The SEM images indicated that the Fe/Cu MOF had a bicone structure with a rough surface and rounded edges. FT-IR analysis indicated the formation of a complex between TA and the Cu/Fe MOF through hydrogen bonding. In addition, the TA loading rate of the Fe/Cu MOF-TA was 21.77%. Furthermore, the minimum inhibitory concentration of the Fe/Cu MOF-TA against Escherichia coli and Staphylococcus aureus was 0.0625 mg/mL. The rate of inhibition of polyphenol oxidase by the Fe/Cu MOF-TA was 76.03%. The results demonstrated that Fe/Cu MOF-TA possesses remarkable antibacterial, antioxidant, and polyphenol oxidase inhibitory properties.

This study aimed to investigate the effects of combined spatial electric field and subzero temperature storage on volatile flavor compounds and microbial community succession in marinated steak. Gas chromatography-mass spectrometry (GC-MS) and high-throughput sequencing of the 16S rRNA gene were performed to analyze the dynamic changes in volatile flavor compounds and the characteristics of the microbial community structure during refrigerated storage, subzero storage, and combined spatial electric field and subzero storage. Volatile flavor compounds with significant characteristics were identified based on odor activity value (OAV) calculations and multivariate statistical analysis, and their associations with the microbial communities were explored using Spearman correlation analysis. The results showed that a total of 39 volatile flavor compounds were detected during the low-temperature storage of marinated steak. Among these, hexanal, benzaldehyde, heptanal, octanal, phenylacetaldehyde, E-2-decenal, 2-methyl-3-heptanone, 2-nonanone, 1-octen-3-ol, dimethyl disulfide, nonanal, and limonene were identified as the main characteristic flavor compounds (OAV>1). Compared with the single refrigeration group, the synergy of space electric field treatment maintained the stability of the composition and relative content of alcohols, aldehydes, ketones, and esters and inhibited the accumulation of spoilage-related flavor compounds. In addition, the space electric field regulated the succession of microbial communities, slowing the rate of transition from psychrophilic bacteria to dominant spoilage bacteria. Correlation analysis indicated that the genera Pseudomonas and Acinetobacter played a key role in flavor changes and would be positively correlated with the production of spoilage markers, such as octanal, dimethyl disulfide, and nonanal. Therefore, space electric fields can inhibit the proliferation of spoilage bacteria in the short term, slow flavor deterioration, and extend the shelf life of prepared beef steaks, providing a highly promising new strategy for the preservation of meat products.

To investigate the effects of microbial solid-state fermentation on the multi-dimensional quality of mung beans, whole seeds were fermented with Aspergillus niger (fermentation temperature 26.5 ℃, inoculum concentration 8 mL/100 g). Changes in the nutritional composition, bioactive substances, antioxidant capacity of mung bean, as well as the physicochemical and digestive properties of mung bean powder during fermentation were analyzed. The results indicated that during solid-state fermentation, the levels of nutrients and bioactive substances in mung beans significantly increased (P<0.05). On day 10 of fermentation, the concentrations of protein, essential amino acids, and soluble dietary fiber were 1.13, 1.06, and 2.65 times those in unfermented mung beans, respectively. The contents of γ-aminobutyric acid, free polyphenols, and free flavonoids were 3.29, 3.42, and 1.81 times higher than those in unfermented mung beans, respectively. Additionally, with the increase in phenolic compounds, the antioxidant capacity of the alcohol extract was significantly enhanced (P<0.05). Compared to unfermented mung bean powder, the fermented mung bean powder exhibited a looser structure, higher solubility, and increased water and oil holding capacities. Rheological analysis showed a decrease in the viscoelasticity and an increase in the fluidity of the fermented mung bean powder. The anti-digestive properties of mung bean powder were enhanced after fermentation. On day 10 of fermentation, the proportion of resistant starch was 21.16%, and the eGI value was 39.99. This study demonstrated that solid-state fermentation with Aspergillus niger can improve the nutritional quality of mung beans, enhance the physicochemical and functional properties of mung bean powder. The findings are expected to provide a theoretical basis for the comprehensive processing and utilization of mung beans and the development of high-quality mung bean fermented foods.

In this study, three types of microspheres were prepared by encapsulating Pediococcus acidilactici (PA) using the gelation method with different concentrations of whey protein isolate (WPI), pectin (PE), and sodium alginate (ALG) as wall materials. The optimal ratio of microsphere wall materials was determined by analyzing the morphological characterization, encapsulation efficiency, and survival of PA after simulated digestion. In addition, the storage stability of the microspheres was evaluated by determining the survival rate of PA after storage under different temperatures and time conditions. Results showed that the ALG-WPI-PE-PA microspheres retained a homogeneous spherical appearance after lyophilization, and the morphology was superior to that of ALG-PA and ALG-WPI-PA microspheres. The encapsulation efficiency of the microspheres was significantly increased (P<0.05) when the WPI concentration was 3.0%, in which the encapsulation efficiency of ALG-WPI-PA was 71.93%, whereas the encapsulation efficiency of ALG-WPI-PE-PA reached 94.33%, which was an increase of 22.4%. In addition, the survival rate of encapsulated PA was significantly increased after simulated in vitro digestion (P<0.05). The optimal concentration of WPI in microspheres was determined to be 3.0%, at which the encapsulation efficiency and survival of PA after digestion were optimized. Storage experiments further confirmed that ALG-3.0%WPI-PE-PA microspheres significantly enhanced the survival rate of PA for a prolonged storage period. This study provides a basis for the further development and application of lactic acid bacteria embedding technology and provides new ideas for the diversification of probiotic preparation products.

In this study, we systematically evaluated the in vitro characteristics of Bacillus velezensis SL to assess its potential as a probiotic. The probiotic properties of strain SL were systematically evaluated using a simulated gastrointestinal tolerance test, antibiotic sensitivity test, cell surface characteristic analysis, antioxidant activity determination, bacteriostatic ability test, and metabolomics technology. The results showed that the survival rate of strain SL in the simulated intestinal fluid exceeded 80%. However, gastric acid tolerance was poor (120 min survival rate was 4.11%), and tolerance to high concentrations of bile salt (0.6%) was good. In addition, strain SL was sensitive to seven antibiotics and did not harbor any resistance genes. The hydrophobicity of the bacteria was 19.08%, and the self-aggregation rate at 12 h was 86%, indicating strong intestinal colonization potential. In the antioxidant experiment, the scavenging rates of strain SL on hydroxyl radicals (·OH) and superoxide anions (O₂⁻·) were 23.84% and 34.18%, respectively, and the scavenging rates of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS⁺) radical were 37.40% and 36.52%, respectively, indicating moderate free radical scavenging abilities. Strain SL showed a certain bacteriostatic effect on pathogenic bacteria such as Salmonella, Clostridium perfringens, and Staphylococcus aureus, and exhibited a good inhibitory effect on Gram-positive bacteria. Metabolomic analysis identified both volatile (such as isobutyric acid and 2-methylbutyric acid) and nonvolatile (such as 9-nitrooleic acid, danye-emodin, and palmitoylglycine) metabolites with potential benefits for digestive enzyme activity and intestinal development, as well as anti-inflammatory, antimicrobial, and antioxidant properties. These results indicated that strain SL has the potential to be developed as a microecological agent. However, the stability of gastric acid should be enhanced by embedding or strain improvement to optimize its application performance.

To elucidate the microbial compositional shifts and spoilage-related microorganism succession in grass carp (Ctenopharyngodon idella) meat during refrigeration, amplicon sequencing technology was employed to analyze microbial profiles at fresh (D0, D3), transitional (D6, D9), and spoiled (D15) stages. Results indicated a significant correlation between microbial community succession in grass carp meat and refrigeration duration, with microbial diversity initially increasing and then decreasing over storage time. Notably, the transitional phase (D6) emerged as the pivotal factor driving substantial divergence in microbial composition. At the phylum level, Actinobacteria (69%) and Proteobacteria (20%) dominated during the initial 3 day refrigeration. A marked structural shift occurred by day 6, with Proteobacteria (51.77%) and Firmicutes (11.76%) becoming predominant. By day 9, Proteobacteria exhibited a substantial increase, ultimately exceeding 98% relative abundance at the spoiled stage (D15), establishing itself as the primary phylum driving spoilage. Genus-level analysis revealed dynamic compositional changes: The dominant genera transitioned from Kocuria (fresh stage, D0~D3) to Pseudomonas, Achromobacter, Acinetobacter, and Psychrobacter (transitional stage, D6~D9), with Pseudomonas ultimately prevailing in the spoiled phase (D15). Principal coordinates analysis (PCoA) indicated high structural similarity among fresh-stage samples (D0, D3), whereas later stages (D6~D15) exhibited significant divergence (P<0.05), displaying dispersed clustering in ordination space. Kruskal-Wallis rank-sum test analysis identified 10 genera with statistically significant (P<0.05) abundance variations during refrigeration: Enhydrobacter, Macrococcus, Brevibacterium, Kocuria, Corynebacterium, Dermacoccus, Psychrobacter, Pseudomonas, Achromobacter, and Brochothrix. The ecological network analysis elucidated the microbial community succession from environmental bacteria to psychrophilic bacteria and ultimately to spoilage bacteria, while identifying stage-specific indicator microorganisms (Enhydrobacter (D0), Macrococcus (D3), and Psychrobacter (D9)). Furthermore, it demonstrated the topological evolution of microbial networks through successive phases of symbiosis (D0, D3), competition (D6), and spoilage dominance (D15). These findings on microbial diversity and structural evolution provide critical insights for monitoring quality assurance and developing targeted preservation strategies in refrigerated grass carp products.

In this paper, 21 strains of Bifidobacteria were isolated and identified from healthy breast milk samples, and the strain with the best activity was selected by spleen lymphocyte proliferation assay, drug sensitivity, haemolysis, bacteriostatic activity, and adhesion capacity evaluation. After identification by 16S rRNA, the lyophilisation technique was optimised and lyophilised microcapsules were prepared. The results showed that the bacterium was Bifidobacterium animalis subsp. lactis, named BA-9. B. lactis BA-9 was safe, with a hydrophobicity of 36.24%, a self-agglutination rate of 77.4%, and could significantly reduce NO activity in RAW264.7 cells, with in vitro Anti-inflammatory potential. Sodium alginate and carrageenan were prepared as a 1:1 composite wall with the addition of a composite lyoprotectant (11.25% skimmed milk powder, 4.93% xylooligosaccharides and 2.74% glycerol). The activity of B. lactis BA-9 microcapsules with the addition of lyophilisation protectant after lyophilisation decreased by only 1.3 lg CFU/g after simulated gastrointestinal fluid digestion. The survival rate of B. lactis BA-9 microcapsules could reach up to 90.03% for 28 days of storage at 4 ℃, which effectively enhanced the stability of storage. This study provides a research basis for the screening of Bifidobacterium bifidum with immuno-anti-inflammatory regulatory activities and the development and application of its lyophilised carrier.

In this study, the screening of lactic acid bacteria with significant inhibitory effect on Listeria monocytogenes. It was determined that the inhibitory substances existed in cell-free fermentation supernatant (CFS), cell pellet or bacterial lysate. The thermal stability, pH stability, and protease sensitivity of the inhibitory substances were investigated. The growth curve and the minimum inhibitory concentration (MIC) of the selected strain were also determined. Finally, the preliminary application was in the cold storage and preservation of Duhei pork. The preservation effect was evaluated by sensory evaluation, pH, meat colour, viable cell counts, total volatile basic-nitrogen (TVB-N) and thiobarbituric acid-reactive substances (TBARS). The experimental results showed that a strain of Lacticaseibacillus paracasei Lab5 from pickle juice showed notable inhibition of Listeria monocytogenes, with an inhibition zone diameter of 38.28±1.97 mm, the inhibitory substances were present in the CFS, which was treated at 60~121 ℃ for 25 min, and its inhibition zone diameter of inhibition against Listeria monocytogenes and Escherichia coli still reached more than 32.07±2.1 mm and 11.53±0.44 mm. No significant difference in bacteriostatic activity in the pH 3.0~8.0 (P>0.05). Proteinase K treatment had the greatest effect on the inhibitory activity, as it reduced the diameter of the circle of inhibition of Listeria monocytogenes by 7.69 mm; It was shown that Lacticaseibacillus paracasei Lab5 CFS had good thermal、pH stability and was less sensitive to six proteases (chymotrypsin, trypsin, enterokinase, proteinase K, papain, pepsin). In the preservation application of refrigerated Duhei pork, it was found that at 9 d of refrigeration, Lacticaseibacillus paracasei Lab5 postbiotics treatment groups (2MIC and 4MIC groups) had significantly reduced the viable cell counts of the meat by 99.7% compared to the control, decreased the pH by 0.33, and reducing TBARS reactants by 0.66 mg/kg, and 0.91 mg/kg in meat (P<0.05), and prolonged the shelf-life by 2 d, when compared with the control group. The scores of sensory testing also indicated that it played a role in color protection, improved the odor and delayed the deterioration of the sensory quality of refrigerated pork. In particular, the 4MIC group showed better effects in all freshness indicators. It's concluded that the postbiotic of Lacticaseibacillus paracasei Lab5, as a new type of natural and safe biological preservative, has an important potential for application in the field of meat preservation, which is of great theoretical and practical significance for the enhancement of food safety.