Abstract:Debranching enzymes are commonly used enzymes in the starch deep processing industry. However， traditional debranching enzymes are unable to fully meet the requirements of green production of starch sugars and comprehensive utilization of by-products. Therefore， it is necessary to explore suitable new types of debranching enzymes. This study screened an oligo-1，6-glucosidase gene (oga) from Paenibacillus sp. STB16 and constructed its Bacillus subtilis expression system. This system achieved heterologous expression of the oligo-1，6-glucosidase. The enzymatic properties and substrate specificity of the recombinant oligo-1，6-glucosidase were explored. The results showed that the enzyme activity of the fermentation supernatant of B. subtilis could reach 162.33 U/mL. The recombinant oligo-1，6-glucosidase had the optimum reaction temperature at 50 ℃ and optimum reaction pH at 6.0. It specifically acted on the α-1，6-glycosidic bonds of branches with degree of polymerization of 1. Compared to other types of debranching enzymes (substrate conversion rate under the detection limit)， the recombinant oligo-1，6-glucosidase exhibited stronger hydrolytic activity towards isomaltose， isomaltotriose， and panose. The substrate conversion rate reach 97.4%-100%， with glucose as the product.Therefore， it is more suitable for treating glucose mother liquor. The glucose content in the first mother liquor， second mother liquor and tail liquor of chromatographic separation was significantly increased by 3.6%， 12.7% and 34.4%， respectively. The research results provide a theoretical basis for the development and utilization of new types of debranching enzymes， and also serve as an important reference for the comprehensive utilization of by-products in starch sugar processing.

Abstract:In order to explore the effect of 60Co gamma irradiation on the structure and glycation products of glycation systems， the ovalbumin (OVA) -glucose system under 60Co gamma irradiation at doses of 0， 25， 50， 75 and 100 kGy was regarded as the research object. The molecular weight， tertiary structure， and secondary structure were determined via SDS-PAGE， fluorescence spectroscopy， and far-ultraviolet circular dichroism spectroscopy， respectively. Meanwhile， high performance liquid chromatography and ultraviolet spectrometry were employed to measure the content of detrimental glycation products including fructosamine， acrylamide， fluorescent AGEs， pentosidine， and melanoidin. The results of increased molecular weight， surface hydrophobicity and β-structure (β-sheet and β-turn) content and decreased intensity of intrinsic fluorescence emission peak and α-helix content showed that 60Co gamma irradiation promoted glycation reaction of OVA in a dose-dependent manner. In addition， the fructosamine and acrylamide in the system during irradiation treatment were increased firstly and then decreased， and the highest contents were presented at 50 kGy. Meanwhile， with the increase of dose， the fluorescent AGEs， pentosidine and melanoidin contents were increased. In short， 60Co gamma irradiation dose would be controlled within 25 kGy to reduce detrimental glycation products in egg products and improve their safety during irradiation treatment. This study would provide a scientific proof for expanding the application of food irradiation technology in egg products in the future.

Abstract:To investigate the mechanism of oxidative stress response during high-density culture of Saccharomyces cerevisiae PY01， transcriptomic analysis was performed after 2 h of oxidative treatment (6 mmol/L H2O₂). The results showed that 393 differentially expressed genes (DEGs) were identified， and based on GO annotation and KEGG enrichment analysis， the identified DEGs were involved in metabolic (e.g. amino acid metabolism， carbohydrate metabolism and energy metabolism)， genetic information and cellular processes (peroxisomes) and other pathways. Under oxidative stress， yeast scavenges ROS by enhancing several antioxidant enzymes， including SOD2， SRX1 and so on， yeast also generates more energy by enhancing glycolysis and the TCA cycle to adapt to oxidative stress， repair damaged proteins， and transport of DNA or maintain metal ions. Meanwhile， molecular chaperones and proteases associated with general stress responses are upregulated. It was shown that the response of Saccharomyces cerevisiae PY01 to oxidative stress is a complex， integrated regulatory network. The discovery and understanding of the mechanism of Saccharomyces cerevisiae PY01 in response to oxidative stress has laid the theoretical foundation for designing control strategies for efficient cultivation of yeast， improving the resistance of the strain， and promoting the use of active yeasts in the production of modern fermentation industries such as fruit wines and other biological products.

Abstract:The effects of acetyl groups in dendrobium polysaccharide (DOP) on gel properties and antioxidant capacity have not been reported in the literature. In this study， we prepared DOP with different degrees of deacetylation by non-homogeneous deacetylation， analyzed its fluid properties， textural properties and total antioxidant capacity of sol and gel， and investigated the effect of acetyl group on the properties of DOP and its mechanism of action. The results showed that the presence of acetyl group made the DOP have good water solubility. With the increase of deacetylation， the viscosity of the sol decreased and the gel formation rate was faster， which changed the thermal sensitivity of the sol when forming the gel and improved the hardness and elasticity of the DOP gel significantly. In addition， the results also showed that the removal of some acetyl groups significantly improved the total antioxidant capacity. Therefore， the rheological and textural properties as well as antioxidant properties of DOP can be adjusted by controlling the amount of acetyl groups of DOP. This study may provide new ideas for the application of DOP in food， pharmaceutical and chemical industries.

Abstract:Objective: To investigate the efficacy and immune tolerance regulation mechanism of partially hydrolyzed whey protein (pHWP) combined with different doses of fructooligosaccharides (FOS) and Bifidobacterium animalis subsp. lactis Bb-12 (Bb-12) in alleviating cow's milk protein allergy (CMPA) in mice. Methods: The four-week-old female BALB/c mice were randomly assigned into normal control， sensitized control， pHWP and pHWP + FOS + Bb-12 intervention groups. During the experimental period (day 0-42)， the mice in the intervention groups were continuously fed with an aqueous solution containing pHWP (15 mg/mL) or pHWP (15 mg/mL)， FOS (0.4 or 4.0 mg/mL) and Bb-12 (1×105 or 106 CFU/mL) instead of drinking water. Mice in the sensitized control group and intervention groups were sensitized by intragastric administration of sterile saline containing 20 mg CMP and 10 μg cholera toxin on day 7， 14， 21， 28 and 35， while mice in normal control group received only sterile saline. On day 42， all mice were oral challenged with 50 mg CMP， and allergic symptom scoring were conducted within 1 h after challenge. Serum antibody and histamine contents， as well as splenocyte proliferation and supernatant Th1， Th2 and Tregrelated cytokine (INF-γ， IL-4 and TGF-β) levels were assessed. Results: The allergic symptom scores (0-1)， serum total IgE (169.4-272.7 ng/mL)， CMP-specific IgE (sIgE) (0.038-0.414 OD)， sIgG1 (0.252-0.379 OD)， and histamine contents (19.56-27.35 ng/mL)， splenocyte proliferation stimulation indexes (1.48-1.58) and supernatant IL-4 levels (18.48-29.60 pg/mL) of mice in the pHWP + FOS + Bb-12 intervention groups were significantly lower than those in the sensitized control group (P<0.05)， while the splenocyte supernatant TGF-β (143.1-177.2 pg/mL)， INF-γ levels (189.5-230.2 pg/mL) and INF-γ/IL-4 ratios (6.46-12.71) were significantly higher than those in the sensitized control group(P<0.05). Compared with pHWP， pHWP + FOS + Bb-12 was more effective in alleviating CMPA， especially when high dose of Bb-12 (1×106 CFU/mL) was applied. No significant difference was found in serum total IgE， CMP-sIgE， splenocyte supernatant IL-4 and INF-γ/IL-4 between pHWP + FOS + high dose Bb-12 intervention groups and normal control group mice. Conclusion: PHWP combined with FOS and Bb-12 could effectively ameliorate CMPA symptoms in mice by improving CMP immune tolerance， which may be related to blocking the secretion of IgE， CMP-sIgE， sIgG1 and histamine， inhibiting the proliferation of splenocytes， and upregulating the level of TGF-β and the ratio of INF-γ/IL-4.

Abstract:Objective: To investigate the effect of sea cucumber cooking liquid (SCCL) dry powder on chronic constipation in mice. Methods: Loperamide hydrochloride was administered intragastrically to establish the chronic constipation model. To evaluate the positive effect of SCCL in intestinal motility of constipation mice， the defecation situation， intestinal ink transit rate and mRNA expression levels of intestinal motility related neurotransmitters and receptors were detected. Result: Compared with the model control group， the intestine ink transit rate of mice in the high-dose SCCL group was significantly increased (P<0.05)， the time of first black faeces was significantly shortened (P<0.01)， and the number and weight of faeces in 6 hours in the low-dose and high-dose SCCL groups were significantly increased (P<0.05)； The number of goblet cells and the content of mucin in the colon of mice were improved significantly (P<0.05)； The mRNA expression levels of M2AChR， M3AChR， 5-HT3R， 5-HT4R and C-Kit in colon tissue were significantly increased (P<0.05). Conclusion: SCCL alleviated constipation by regulating intestinal peristalsis related neurotransmitters such as ACh， 5-HT and its downstream signaling pathways， eventually increased the number of ICC cells， improved intestinal motility and promoted intestinal peristalsis.

Abstract:Lactic acid bacteria (LAB) and yeasts are the dominant microorganisms in the fermentation process of pickled vegetables， and their relationship and fermentation characteristics are important factors affecting the quality of products. In the study， high-yield AI-2 LAB and aroma-producing yeasts were screened from commercial pickled vegetable using Vibrio harveyi BB170 report method and total ester titration method. The mixed fermentation conditions of LAB and yeast were further optimized by orthogonal test. The differences in AI-2 production， acid production rate， acid resistance， salt tolerance， and nitrite degradation between the mixed strains and LAB alone fermentation were compared. Effect of yeasts on the fermentation characteristics of LAB with high production AI-2 was explored. These results showed that Lactobacillus plantarum SR with high yield of AI-2 and Pichia membranaceus S-0-1 with ester content of 0.6 g/L were obtained. The mixed fermentation conditions were as follows: inoculation amount 2%， inoculation ratio 1 ∶ 1(SR:S-0-1)， culture temperature 28 ℃. Under optimized fermentation conditions， compared with L. plantarum SR alone fermentation， the AI-2 synthesis ability， acid tolerance rate (pH = 3) and the salt tolerance rate at 5% of the mixed strains was increased by 1.4 times， 4.8 times and 24.66%， respectively. Meanwhile， the acid production rate of the mixed strains was increased. but there was no significant change in the degradation rate of nitrite of the mixed strains， which basically maintained at 98%. The above results indicated that Pichia membranaceus S-0-1 could increase the yield of AI-2 signal molecules in L. plantarum SR， result in enhancing the fermentation characteristics of the LAB and yeasts. This study aimed to provide a theoretical basis for further exploring the mutual regulation mechanism of AI-2 / LuxS quorum sensing in mixed fermentation system of LAB and yeasts.

Abstract:Temperature is used for classifying Daqu as high temperature Daqu， medium temperature Daqu and low temperature Daqu， since it significantly affects the physical and chemical indexes and microbial community structure of Daqu. The effect of temperature varied in a small range during the manufacture of Daqu for Light-flavor baijiu brewing on its microbial and physicochemical properties is still unclear. In this study， the effect of microbial community structure and physicochemical properties of Hongxinqu by different peak-temperature were compared. The results showed that there was no significant difference in microbial alpha diversity between the two groups of Hongxinqu from different peak temperature. However， the microbial community structure at the genus level has changed significantly. In Hongxinqu samples from peak-temperature rised 5 ℃， Thermoascus increased from 64.7% to 78.4%， and Saccharomycopsis fibuligera decreased from 33.3% to 15.2%， Eurotium and Rhizopus producing amylases were also significantly increased. Similarily， in Hongxinqu samples from peak-temperature rised 5 ℃， several bacteria genus significantly increased included Acetobacter， Weissella， and Staphylococcus， all of which were beneficial to the formation of Baijiu flavor， while Actinomycete Saccharopolyspora which is little in general Daqu samples decreased from 26.7% to 8.8%. About of the physicochemical properties， when the peak-temperature increased by 5 ℃， the saccharification of Daqu decreased from 596.9 U to 516.1 U and the liquefaction decreased from 1.26 U to 1.05 U， but the decrease was not significant； The fermenting power and liquor-producing power have increased， with the fermenting power increasing from 0.74 U to 2.27 U and the liquor-producing power increasing from 7.1% vol to 8% vol. About of the physicochemical properties， the temperature increment of a small range did not significantly reduce the saccharification power and liquefaction power， while the fermenting power and liquor-producing power were increased. The overall results showed that increase of peak-temperature during Hongxinqu making process according to the actual situation can effectively optimize the microbial community structure of Hongxinqu and improve its comprehensive quality， which provided a theoretical basis for Hongxinqu production of high quality and highyield.

Abstract:To realize the high-value utilization of buckwheat protein resources， α-glucosidase-inhibiting glycopeptide (α-GIG) was prepared by fermentation of Lactobacillus plantarum and Streptococcus thermophilus which were selected from 6 strains. One-factor-at-a-time method aimed to determine the level of experimental factors and a further response surface experiment was used to optimize fermentation. The fermentation broth was separated and purified by Sephadex G-25 and reversed phase-high performance liquid chromatography (RP-HPLC) to prepare α-GIG. The method of β-elimination reaction was used to determine the type of glycopeptide bond and infrared spectroscopy was used to analyze the secondary structure. The inhibitory effects of α-GIG on α-glucosidase was investigated by enzyme kinetics. The results showed that when the inoculum was 2%， pH was 7.5， solid-liquid ratio was 1∶14.8 and fermentation time was 2.8 d， the α-glucosidase inhibition rate was 70.83%. I1， I2， I3 were separated from Sephadex G-25， and I2 with the best enzyme inhibitory effect whose IC50 is 1.72 mg/mL. I2 was further separated and purified by RP-HPLC to obtain α-GIG with a purity of 94.17%. Fourier transform infrared spectroscopy suggest that the secondary structure composition was estimated as 70.51% β-folding， 18.95% α-helices and 10.54% β-corner. β-elimination reaction demonstrated the existence of O-glycosidic linkage in α-GIG. The results of the enzyme inhibition kinetics study showed that α-GIG exhibited a mixed-type noncompetitive inhibition of α-glucosidase. Therefore， α-GIG had the potential to be developed as a natural α-glucosidase inhibitor.

Abstract:Clam is one of the important economic shellfish in mariculture in China， with high protein content and complete amino acid species. In this paper， clam was used as experimental material to extract clam protein isolate， and clam protein isolate-dextran conjugates were prepared by wet heat glycosylation reaction. With emulsifying activity and emulsifying stability as the evaluation indexes， the conditions of glycosylation reaction were optimized by single factor combined with response surface method. The result showed that the optimal conditions were 109 ℃， 89 min， pH 11， mass ratio of protein to dextran was 1∶1. Under these conditions， the emulsifying properties and emulsifying stability of glycosylated compound were 1.22 and 75.56， respectively. The results of free amino group content， Fourier transform infrared spectroscopy (FT-IR)， thermal stability， fluorescence spectroscopy and scanning electron microscopy (SEM) showed that the glycosylated product was formed by glycosylation of clam protein isolate and dextran. This study improved the functional properties of clam protein and provided a theoretical basis for expanding the application of clam protein in food industry.

Abstract:This study aimed to investigate the inactivation effect of HPTS combining with egg white lysozyme on the spores of Bacillus subtilis. The spores were treated with pressure 200 MPa at 25， 65 ℃ and 75 ℃， and egg white lysozyme at 0.05%， 0.1% and 0.3%. After treatment， the inactivation rate of Bacillus subtilis spores， leakage of nucleic acid and protein， the change in the cell membrane ATPase activity， the changes in inner membrane permeability of spores and the damage on protein of the spores were determined. The results showed that HPTS and egg white lysozyme synergistically inactivated the spores， and the survival concentration of spores decreased by 3.91 lg (CFU/mL) after 200 MPa/75 ℃ combining with 0.3% lysozyme treatment. HPTS combining with lysozyme treatment significantly increased the protein and nucleic acid leakage and conductivity of the spores， significantly decreased the Na+/K+-ATPase activity， decreased the stability of the budding spore proteins， and significant increases in the permeability of the inner membrane of the spores. In summary， HPTS combining with egg white lysozyme treatment inhibited the activity of key enzymes in the spore metabolic pathway， while disrupting the spore wall， inner membrane and other structures of Bacillus subtilis budding spores， changed the physiological properties of spores， and eventually led to spore inactivation.

Abstract:In this paper， the inactivation kinetics of potassium sorbate-assisted high pressure thermal sterilization (HPTS) on Bacillus subtilis spores were studied. First-order kinetics model， Weibull and Log-logistic kinetics models were used to fit the inactivation curve of B. subtilis spores by potassium sorbate-assisted HPTS. By analysis of precision factor (Af)， bias factor (Bf)， root mean square error (RMSE)， coefficient of determination (R2)， In the three models， Log-logistic Kinetic model fitted best the spore sterilization effect of potassium sorbate-assisted HPTS (R2=0.986). When potassium sorbate (0.2 g/100 mL) assisted HPTS (600 MPa， 75 ℃， 25 min)， the inactivation effect was the best， and the spore inactivation was 6.10 lg(CFU/mL). Potassium sorbate assisted HPTS treatment was applied to the inactivation of spores in muskmelon juice， it was found that the browning degree was significantly reduced， after 28 days of storage， the absorbance of potassium sorbate (0.1 g/100 mL) assisted HPTS (600 MPa， 75 ℃， 25 min) at 420 mn reached 0.093， The absorbance of the HPTS-treated control sample was 0.058. Scanning electron microscope was used to observe the microstructure of Bacillus subtilis spores in muskmelon juice before and after treatment， and it was found that the morphological structure of the spores changed after treatment. In conclusion， potassium sorbate assisted HPTS has significant application value.

Abstract:To investigate the effects of different thawing media such as plasma activated water(PAW)， slightly acidic electrolytic water (SAEW)， and 3% NaCl solution on the quality of jumbo squid， the frozen samples were thawed in the three abovementioned media at 4 ℃. The effects of different thawing media on water retention， protein oxidation and structure of jumbo squid were analyzed. Results showed that PAW as thawing medium significantly improved the water-holding capacity of sample(P<0.01)， and the cooking loss rate was 28.67%， which was significantly lower than that of the other three groups. Compared with other treatment groups， samples treated with PAW had the lowest carbonyl and dityrosine content and the highest sulfhydryl content， indicating a good inhibition of protein oxidation. The results of turbidity， endogenous fluorescence and UV spectra analysis showed that the PAW treatment group could reduce the degree of protein denaturation and maintain structural stability. Taken together， the PAW treatment had the best effect on water retention and autoxidation of jumbo squid.

Abstract:Objective: in order to explore the effect of magnetic field assisted freezing on the quality of glutinous rice balls， to develop a new type of auxiliary freezing method for rice flour products， and to study the effect of auxiliary freezing on the quality of glutinous rice balls under different magnetic field intensities. Methods: the method of plate freezing and magnetic field assisted freezing was used in this study. The freezing rate， water loss rate， chromaticity， texture characteristics， gelatinization characteristics， freezing water content and water binding state of Tangyuan powder were measured to reveal the influence of magnetic field assisted freezing on its quality change. The results showed that compared with the control group， there were significant differences in the freezing rate， water loss rate， chromaticity， texture characteristics， gelatinization characteristics and freezing water content of Tangyuan powder after magnetic field assisted freezing (P<0.05). It was found that the freezing rate of Tangyuan powder frozen by magnetic field was accelerated at 24 Gs， and the time of entering the maximum ice crystal formation zone was advanced by 4 min， making the ice crystal volume smaller； The water loss rate decreased by 37.57%， the brightness increased by 3.63%， the transmittance increased by 14.92% and the hardness decreased by 11.74%. From the water binding state， the frozen water content of Tangyuan powder was significantly lower than that of the control group， and decreased by 11.64% at 24 Gs； However， after the magnetic field assisted freezing， the peak viscosity of the dumplings increased by 7.81% and the retrogradation value increased by 3.93%； There was no significant difference in water binding state. Conclusion: when the magnetic field strength is 24 Gs， the frozen quality of Tangyuan powder is the best， which can obviously improve the quality indexes of Tangyuan powder， such as water loss rate， chroma， hardness and frozen water content， and provide a theoretical reference for the development of magnetic field assisted freezing on rice flour products in the future.

Abstract:Taking wheat bread as the control， this study explored the effects of five exogenous plant and animal proteins， soybean protein isolate， pea protein isolate， corn gliadin， whey protein concentrate and egg white protein， on the mixing characteristics， gelatinization characteristics， rheological characteristics， specific volume and sensory analysis of rice dough and bread. The results showed the addition of exogenous proteins can reduce the retrogradation value of rice dough to a minimum of 211 cP， increase the specific volume of bread to 1.810 mL/g， decrease hardness by about 55.3%， and decrease adhesive strength to 2 710.12 g. The soybean protein group with 12% plant protein had the largest number of pores， fine texture and uniform color， and the water holding capacity and sensory quality were the best. The bread hardness of 9% whey concentrated protein group in animal protein decreased significantly by about 2 032.9 g(P<0.05). At this time， the dough hardness was closest to that of wheat dough， and the elasticity was 0.82%. The taste was soft， which had the best effect on improving the texture characteristics of rice bread. Therefore， the quality of rice bread can be better improved when the addition of soybean protein in plant protein is 12% and whey concentrated protein in animal protein is 9%.

Abstract:In order to promote the strategy of potato staple food， this paper investigates the effect of potato starch addition on the dough characteristics， cooking， textural and digestive properties of fermented noodles by adding different levels of potato starch. The results showed that with the increase of potato starch addition (0%-55%)， the gelatinization initial temperature of the mixed powder decreases， the enthalpy value increases， and the termination temperature does not change significantly. The water absorption， formation time and stabilization time of the flour mix dough all tended to decrease and the dough tended to be more of a solid material， resulting in a significant decrease in the firmness， elasticity and chewiness of the fermented noodles (P<0.05). By simulated in vitro starch digestion， the rate of starch hydrolysis was found to increase with the addition of potato starch， and the predicted value of glycemic index was significantly lower with the addition of potato starch compared to the control group (P<0.05). In summary， the pasting， textural and digestive characteristics of the flour dough mix and fermented noodles were better at 45% potato starch addition.

Abstract:In order to explore the impact of raw materials and heat treatment on the processing quality of lotus root whole powder， different varieties and different growth periods of lotus root were selected， and the effects of steam heating at 100 ℃ and 120 ℃ on product color， sugar content， digestion characteristics， thermodynamic properties and gelatinization characteristics were investigated. The results revealed variations in nutrient composition and digestive characteristics among different cultivars and growth stages of lotus root. Heat treatment led to changes in the qualities of whole powder. Especially， total starch content decreased by 2.48%-18.41%， with an increase in the ratio of fast digestible starch by 19.06%-34.56%， slow digestible starch by 28.66%-57.70%， while resistant starch decreased by 48.56%-87.21%. Digestion patterns for saccharides altered significantly， resulting in a rise in total release amount of reducing sugar by 14.05%-93.78%. The initial， peak and termination temperatures of gelatinization significantly decreased (P<0.05)， and the valley viscosity and final viscosity of high pressure heating powder also significantly decreased (P<0.05). Heat treatment significantly influenced nutritional characteristics and flushing characteristics of lotus root powder； these findings can serve as valuable references for controlling its processing quality.

Abstract:In order to explore the changing of lignin in bamboo shoots， the Phyllostachys praecox were stored at room temperature (25 ℃) and low temperature (4 ℃)， and the enzyme activity and relative gene expression related to changes in lignin content and components were studied. The results showed that: at room temperature， the bamboo shoots showed changes such as yellowing and decay after stored for 6 days； under low temperature storage conditions， the bamboo shoots showed yellowing and decay until the 24th day. Stored at low temperature for 6 days， the lignin content was 13.22 mg/g， and increased to 26.31 mg/g on the 24th day. The total amount of amino acids did not change much under low-temperature storage conditions， and it showed a slow downward trend at room temperature. On the 6th day， the amino acids decreased by 21.78% at the room-temperature storage. Enzyme activities such as phenylalanine ammonia lyase(PAL)， peroxidase(POD)， cinnamyl alcohol dehydrogenase (CAD)， and cinnamic acid-4-hydroxylase (C4H) showed a significant upward trend with extending storage time. Enzyme activities under room temperature storage were higher than those under low temperature storage. Low temperature reduced the activity of bamboo fiber-related enzymes by inhibiting the expression of genes related to bamboo lignin formation， thereby slowing down the process of lignification. Under the low temperature， the number of genes related to down-regulated expression increased with the extending of storage time. The most significant down-regulation of genes were observed at 24 d， while the amount of up-regulated genes was relatively small， with the smallest number observed at 12 d. The relative expression levels of LAC-10， POD-10， HCT-10， CAD-10， and CCR-10 genes showed an overall upward trend under low temperature storage， while the relative expression level of COMT-10 gene decreased continuously. This study provides a theoretical basis for controlling post-harvest quality of bamboo shoots.

Abstract:In this study， 'Hongyang' kiwifruit was used as raw material. We used ethylene as an intervention method to investigate the changes in physicochemical indexes， ethylene production rate， and the activities of ACS and ACO， the key enzymes involved in ethylene production during postharvest storage period. In addition， the expression differences of each member of the gene family affecting ACS and ACO were also studied using real-time quantitative PCR combined with bioinformatics analysis， and the key genes for the transition from ethylene production system I to II were cloned. The results showed that the hardness of 'Hongyang' kiwifruit decreased from 8.7 kg/cm2 to 0.02 kg/cm2 and the content of soluble solids increased from 8.1% to 16.9% during postharvest storage， and the ACS and ACO activities in both the ethylene intervention and non-intervention groups showed a trend of first increase and then decrease， which was consistent with the trends of respiratory intensity and ethylene release rate. Besides， The ACS， ACO activity and respiration intensity of the samples in the non-intervention group reached their peaks on the 9th day， and the ethylene release rate peaked on the 7th day， while the ethylene treatment group all peaked on the 5th day， indicating that ethylene could accelerate the arrival of the kiwifruit respiration peak， ethylene release rate peak and the peaks of ACS， ACO activity. Six ACO genes were successfully cloned from 'Hongyang' kiwifruit fruit， named as AcACO1-6. The sequence of the coding region of AcACO1-6 was 1 101-1 270 bp， encoding 352-402 amino acids， and the nucleotide sequence homology was 28.3%-99.3%. Moreover， all ACO genes had the same conserved structural domain PLN02299， which had ACO activity. Finally， the qRT-PCR results showed that the relative expression of ACO is 500 times higher than that of ACS， and there was a high consistency between the expression changes of AcACO1 and AcACO3 in the ACO gene family and changes in ethylene production and enzyme activity(R>0.85). Particularly， their promoter sequences were enriched with cis-acting elements involved in transcriptional regulation. Overall， the findings suggested that AcACO1 and AcACO3 were pivotal genes in the transition from ethylene production system I to system II.

Abstract:To investigate the effect of exogenous melatonin on postharvest black spot disease of apricot fruit. Using Xinjiang 'Saimaiti' apricot as test material， the sample were vacuum impregnated into different concentrations of melatonin (50， 100， 200 μmol/L) under pressure of 0.05 MPa for 2 min， then atmospheric pressure was restored， and the sample was maintained in the impregnation solution for 8 min， distilled water treatment was used as the control group， naturally dried， and then stored at (0±1) ℃ and 90%-95% relative humidity for 48 h， all samples inoculated with Alternaria alternata， and stored under the same conditions. The lesion diameter and disease incidence of apricot fruits， and the activities of phenylalanine ammonia-lyase (PAL)， cinnamic acid-4-hydroxylase(C4H)， 4-coumaric acid CoA ligase (4CL)， polyphenol oxidase (PPO) and cinnamyl alcohol dehydrogenase(CAD)， and the total phenolic， lignin and flavonoid contents were measured regularly. The results showed that exogenous melatonin treatment significantly reduced the lesion diameter and disease incidence of apricot fruits. On day 42 of storage， the diameters of lesions in different melatonin treatment groups (50， 100， 200 μmol/L) were 8.41， 7.20 mm and 8.01 mm， respectively， which were 5.68%， 19.32% and 9.45% lower than those in the control group (P<0.05)， and the inoculation incidence was 10.00%， 21.11% and 12.22% lower than that of the control group(P<0.05)， respectively， and 100 μmol/L melatonin treatment group inhibited the growth of Alternaria alternatas best. Melatonin treatment increased the enzyme activities of PAL， C4H， 4CL， PPO， and CAD and promoted the accumulation of total phenol， flavonoid， and lignin contents in apricot fruit. At the end of storage， the activities of PAL， C4H， 4CL， PPO and CAD of the melatonin-treated group were 400.75， 0.95， 0.48， 0.52， and 0.61 U， respectively， which were 15.18%， 41.04%， 18.51%， 15.63%， and 65.04% higher than those in the control group (P<0.05)， and the total phenol， flavonoid， and lignin contents of melatonin group were 1.10， 1.22， and 1.30 times higher than those of the control group(P<0.05). Those findings suggested that exogenous melatonin could regulate phenylpropanoid metabolism to improved the resistance of apricot fruits to the black spot disease.

Abstract:Quorum sensing (QS) is a communication pattern between bacteria， hence the inhibition of bacterial QS system could be used as a new strategy to the control the spoilage caused by bacteria， and to some extent could avoid the bacteria drug resistance. In the study， dandelion water extract mediated biosynthesis Ag nanoparticles (D-AgNPs) was prepared with AgNO3 as silver source and dandelion water extract as reducing agent. Its structure was characterized by ultraviolet visible absorption spectroscopy(UV-vis)， dynamic light scattering(DLS)， Zeta potential， X-ray diffraction (XRD)， Fourier transform infrared spectroscopy (FTIR)， scanning electron microscopy (SEM) and X-ray energy spectrum(EDS). It was found that the synthesized D-AgNPs were spherical， with an average particle size of 13.9 nm and Zeta potential of (-14.07±0.25) mV. The effects of D-AgNPs on the growth of two Hafnia strains and quorum sensing regulated virulence factors such as biofilm， AHLs， proteases， exopolysaccharides， swimming and swarming motilities were determined. It was found that the minimum inhibitory concentration of D-AgNPs against Hafnia was 128 μg/mL， and could inhibit the formation of the biofilms of Hafnia at 1/16~1/2 MIC (8-64 μg/mL)， whereas promoted its biofilm formation at 1/128~1/32 MIC(1-4 μg/mL). D-AgNPs showed different inhibition abilities on the AHLs and protease production， as well as swimming and swarming motilities； however， sub-MIC D-AgNPs promoted the production of exopolysaccharides. It is proved that D-AgNPs could be used as quorum sensing inhibitor.

Abstract:Objective: To investigate the genomic differences of different phenotypic colonies of Lacticaseibacillus paracasei PC-01 after high-density fermentation. Methods: Ten L. paracasei PC-01 isolates with different phenotypic characteristics after high-density fermentation were subjected to whole-genome sequencing using second-generation sequencing technology， and the differences between these ten L. paracasei isolates were revealed by comparative genomics methods. Results: The genome size of the 10 L. paracasei PC-01 isolates ranged from 2.69 to 2.83 Mb， the GC content ranged from 46.50% to 46.64%， and the number of CDs ranged from 2 793 to 3 406， with small differences in genome size and GC content among the different colonies. The results of functional annotation showed that the number and types of genes encoding carbohydrate and protein metabolism， as well as genes involved in the synthesis and degradation of amino acids and their derivatives varied among different strains. Phylogenetic trees were constructed based on the core genes， and it was found that strains with similar colony morphology were located in the same branch. SNPs showed that every two isolates with the same colony morphology had the same mutation site， which further confirmed the association between colony morphology and genotype. Analysis revealed non-synonymous mutations in genes related to glycosyltransferases (epsJ， pbpF， ponA， etc.) and the ABC protein family (yheS， bceB， bceA， pcrA and uvrA， etc.) in all 10 isolates， allowing the strains to better adapt to their environment and thus survive the high density fermentation process. Colonies PC-01-3 and PC-01-4 differed markedly from other colony morphologies with non-synonymous mutations in the ltaS gene. The deficiency of lipophosphatidic acid synthase(LtaS) caused the bacteria to exhibit impaired cell division and growth defects， which may be the main cause of the differences in colony morphology. Conclusion: In this study， 10 isolates of L. paracasei PC-01 were analyzed at the genome-wide level， and the differences between colonies of the same strain were resolved to provide data for the follow-up study of L. paracasei PC-01.

Abstract:Objective: The development of a method for detecting pesticide residues based on surface enhanced Raman scattering (SERS) substrate of MXenes (Ti3C2Tx) of two-dimensional nanoparticle materials. Methods: Firstly， a single layer of negatively charged MXenes two-dimensional material was prepared by fluorine salt etching method， and then synthesized 30 nm of gold nanoparticles (AuNPs) modified by the positively charged surfactant CTAC， and AuNPs/MXenes was prepared with MXenes loaded with AuNPs by electrostatic adsorption. Secondly， the concentration ratio of AuNPs and MXenes colloidal solutions was optimized with R6G as the Raman probe molecule. Thirdly， it is used for the detection of thiram. Results: The Raman enhancing factor of AuNPs/MXenes is 1.7×105， which showed good SERS activity. A linear relationship was constructed between the strength of the thiram Raman characteristic peak at 1 379 cm-1 and the logarithm of the thiram pesticide residue concentration， and the standard curve was obtained: y=888x+1 151， the coefficient R2 was 0.986， and the detection limit was 0.051 ng/mL， which was lower than the national standard of 5 ng/mL. The QuEChERS method was used to pretreat the citrus samples， and the SERS detection of thiram residue in the real citrus samples was realized， and the recovery rate ranged from 101.1% to 122.0%. Conclusion: The SERS substrate prepared based on the MXenes structure has potential for thiram detection in citrus samples.

Abstract:Salmonella is the main cause of human diarrhea worldwide， which seriously endangers human and animal health. Traditional detection methods are time-consuming and cumbersome， so it is of great significance to carry out rapid， simple and sensitive visual detection methods. In this paper， a probe that can bind to the target sequence was designed and combined with gold nanoparticles (AuNPs). The target sequence was amplified by saltatory rolling circle amplification (SRCA). After denaturation at high temperature， it became a single chain. After binding with the probe on gold nanoparticles， gold nanoparticles were released. Under the action of MgSO4， the aggregation showed blue visible to the naked eye， which was judged to be positive and negative to be purple. Therefore， a simple， fast and sensitive visual detection method was established. The results showed that the method had good specificity and could distinguish 8 Salmonella positive and 8 non-Salmonella negative. The sensitivity of visual detection was 5.5×100 CFU/mL. The milk samples were artificially contaminated with Salmonella， and the detection limit was 3.7×100 CFU/mL. Comparison with GB 4789.4-2016 method for detection of 50 actual samples， the sensitivity of this method was 100.00%， the specificity was 97.87%， and the coincidence rate was 98.00%. The SRCA-AuNPs visual detection method established in this paper has high application value， and the results are visible visually， which is suitable for on-site visual detection and grassroots units.

Abstract:Thioflavin T(ThT) can bind to G-quadruplex through non-covalent interaction to form G-quadruplex/ThT complex， showing strong fluorescence intensity， while free ThT fluorescence is very weak. In the presence of florfenicol (FF)， the high affinity of the aptamer(Apt) with a G-quadruplex structure to the target enables the formation of the Apt/FF complex and the release of ThT， resulting in a decrease in fluorescence intensity. Based on this feature， this study designed a sensitive and rapid on-site detection system for the detection of florfenicol， a label-free fluorescent aptasensor based on G-quadruplex/thioflavin T. The detection range of this aptamer sensor was 0.0128-200 ng/mL， the actual detection limit was 0.0128 ng/mL， and the total detection time was 10 min. At the same time， the recovery rate of the actual spiked samples (milk and eggs) was calculated， and the spiked recovery rate was between 91.2% and 117.1%. The established label-free fluorescent aptasensor has the advantages of high specificity， low cost， and short time-consuming， and can be used for on-site detection of actual samples.

Abstract:Excessive psychrophilic bacteria in raw milk can produce high levels of heat-stable protease and lipase， both of which are important causes of quality problems when cow's milk enters the shelf life. In order to explore the microbial diversity of cows' living environment in pasture and different stages in the raw milk circulation process， the pollution source of psychrophilic bacteria in the pasture was found out. In this study， we collected five samples in a large-scale dairy farm in Hebei Province: TMR feed， cowshed pad soil， the first three milks， the normal milk after the first three milks， and the raw milk in the milk tank， and analyzed the bacterial community structure， psychrophilic species， abundance of psychrophilic bacteria in all samples by using metagenomic shotgun sequencing technology. The results showed that the mainly microbial were Proteobacteria， Firmicutes， and Actinobacteria at phylum level. At the genus level， the main genera were Anaplasma， Streptococcus， Enterococci， Spirospirita， Bacillus， and Pseudomonas. The soil of the barn contains 99.63% and 96.39% of the species of Pseudomonas in the normal milk and the total milk of the pasture storage tank， indicating that the soil of the barn mat is a potential source of pollution of various types of Pseudomonas.

Abstract:The giant salamander， as a precious amphibian， is rich in nutritional value. To fully and efficiently utilize its processing by-products， acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) from giant salamander bone were isolated and characterized. The yields of salamander bone ASC and PSC were 10.71% and 13.11%， respectively. The stable triple helical structure of collagen was revealed by Fourier transform infrared spectroscopy. SDS-PAGE electropherograms showed that both samples were type I collagen with high levels of imino acids (179-187/1 000 residues). Their solubility was highest at pH 6. The thermal denaturation temperature (45.78-46.51 ℃) was significantly higher than that of marine and freshwater fish species. Under SEM， the collagen showed dense flakes and irregular holes. These results show that the characteristics of giant salamander bone collagen are similar to mammalian collagen， and it has the potential to become its substitute， which provides a basis for its subsequent research and development and utilization.

Abstract:Houttuynia cordata Thunb (H. cordata) is a medicinal and edible homologous plant. The abundant water-soluble polysaccharides of H. cordatahave been proved to have a variety of biological activities. However， the current research on polysaccharides from H. cordata mainly focuses on the whole plant or aboveground parts. The differences in the structure and activity of polysaccharides from different parts of H. cordataare rarely reported. In this study， the polysaccharides from the rhizome (RHCP)， stem (SHCP) and leaf (LHCP) of H. cordata were extracted and separated， and their structural characterization， antioxidant activity in vitro and α-glucosidase inhibitory activity were determined. The aim was to explore the relationship between the structure and biological activity of H. cordata polysaccharides (HCPs). Results showed that polysaccharides in different parts of H. cordata were acidic polysaccharides， which were composed of glucose， galactose， arabinose， rhamnose， galactose uronic acid， and a small amount of fucose， mannose， xylose， and glucuronic acid， but the proportions are different； The molecular weight was 4.11×104 u to 1.20×106 u； The infrared structure was basically the same； LHCP had higher content of methyl and acetyl groups， and their contents were 0.95% and 1.05% respectively； The surface morphology of the three polysaccharides was smooth and flat； LHCP was not triple helix polysaccharide， while RHCP and SHCP existed triple helical structure. The in vitro antioxidant and α-glucosidase inhibition ability of LHCP were the strongest. It was found that the structure and activity of polysaccharides from different parts of H. cordata were different， providing a theoretical basis for the study of the structure-activity relationship of HCPs and providing a theoretical basis for the development and utilization of HCPs.

Abstract:Hongqu rice wine was brewed with glutinous rice as raw material and Hongqu as starter. Monascus and Saccharomyces cerevisiae were the core microorganisms in the brewing system. In this paper， using glutinous rice as the fermentation substrate， Monascus purpureus， Monascus ruber and Monascus kaoliang were combined with S. cerevisiae to study the effects of different combinations and fermentation modes (simultaneous fermentation and sequential fermentation) on the production of volatile components. A total of 89 volatile flavor compounds were identified from fermented rice wine based on headspace solid phase microextraction-gas chromatography mass spectrometry (HS-SPME-GC-MS). Heat map analysis showed that the combined fermentation of Monascus and S. cerevisiae produced more aroma substances than the pure fermentation of Monascus， and the sequential fermentation produced more aroma substances than the simultaneous fermentation， especially the sequential fermentation of M. purpureus， M. ruber and S. cerevisiae. According to the principal component analysis of volatile flavor components of different Monascus and S. cerevisiae combined fermentation， M. purpureus and M. ruber and S. cerevisiae will produce more volatile flavor components under the sequential fermentation mode， and their flavor compositions were close to each other. Through the analysis of the content difference of volatile flavor components， isobutanol， 1-heptanol， (3Z)-3-nonene-1-ol， 2-tetradecanol， (Z)-5-octene-1-ol， decanal， ethyl caproate， ethyl decanoate， 9-decenoate， ethyl phenylacetate， ethyl acetate， 1，2-dimethoxy-4-vinyl benzene， acridine were the characteristic volatile flavor substances in the combined fermentation products of Monascus and S. cerevisiae. The results of this study could provide a theoretical basis for the improvement of flavor quality and quality control in the industrial production of Hongqu rice wine.

Abstract:Objective: To establish a reliable， accurate， and objective method for evaluating the quality of Dracocephalum rupestre Hance tea (DRH) through statistical analysis. Methods: The correlation and linear regression relationship between the color difference value， absorbance value， water extract content of DRH samples， and sensory evaluation scores of tea soup were determined and analyzed. Results: There is a significant positive correlation between the sensory evaluation score of DRH and the L value of lightness and darkness. There is a significant negative correlation between the value of the red-greenness indicator a and the yellow-blueness indicator b value. And there is a significant positive correlation between the color difference derivative value Cab and color difference ΔE. Therefore， it can be used to reflect the quality of DRH that the color difference parameters L， a， b， Cab， and ΔE. There was a linear relationship between the total score of sensory evaluation (Y1) and brightness L (X1)， chroma a (X2)， and chroma b (X3). The established prediction equation was Y1=24.93+6.78X1-66.55X2-21.35X3 (P<0.05， R2=0.62). There was a very significant positive correlation between the absorbance value of DRH soup and various sensory scoring items. There was a linear relationship between the absorbance value (Y2) and appearance (X1)， aroma (X2)， soup color (X3)， taste (X4)， leaf bottom (X5)， and the total score (X6). The linear equation was Y2=-0.008-5.43×10-5X1+7.33×10-5X2+0.001X3+0.001X5-0.001X6 (P<0.01，R2=0.96). There was a very significant positive correlation between the content of DRH extract and various sensory scoring items. Water extract content (Y3)， appearance (X1)， aroma (X2)， soup color (X3)， taste (X4)， leaf bottom (X5)， and the total score (X6) were selected. The established prediction equation was Y3=-0.036+6.21×10-5X1+0.002X2+0.005X3-4.61×10-5X4-0.003X5+0.001X6(P<0.05，R2=0.87). Conclusion: This study established an evaluation method for the quality of Maojian tea， which provided the reference for the production and processing of herbal tea.

Abstract:Carbohydrates are one of the most important food components， and their flexible and complex molecular structures make it difficult for existing experimental methods to obtain comprehensive and detailed information at the molecular level. Molecular dynamics (MD) simulations， as a theoretical computational method， have been widely used in the study of carbohydrates in recent years， providing information on the conformation as well as the driving force， binding energy and interaction site of intermolecular interactions， which is an effective supplement and deeper exploration of real experiments. This review introduced the definition， software， force field， methods， general processes and new approaches of MD simulations. Combined with research examples， it focused on the important role of MD simulations in the studies of carbohydrate conformation， aggregation and the effect of processing on carbohydrates， and elucidated the great potential in resolving the interaction mechanisms between carbohydrates and other components. It is expected to provide theoretical guidance for the in-depth analysis of the conformational relationships of carbohydrates and the expansion of their application efficiency.

Abstract:Capsaicin is an active ingredient that characterizes the pungency of pepper， and is the key to the ‘door of spicy sensation’， that is， the source of spicy sensation. Through the interaction with the oral cavity， capsaicin substances make TRPV1 activated by capsaicin， increase intracellular calcium ions， trigger nerve endings， release neuropeptides， and finally cause the formation of pain sensation in the cerebral cortex， thus generating a spicy sensation. It has been found that capsaicin has certain damage to taste. Capsaicin may directly or indirectly inhibit the transmission of taste nerve by reducing the number of taste buds and changing the excitability of taste transduction or taste receptor cells， thus causing damage to relevant taste cells and nerves. This paper summarizes the regulation and damage mechanism of capsaicin to taste and the research status of the new capsaicin taste interaction technology， discusses the shortcomings of its potential influence mechanism， and looks forward to the future research direction， in order to provide reference for the application of capsaicin in food and the prevention of damage caused by capsaicin.

Abstract:Heterocyclic amines are a kind of harmful substance produced by a series of complex reactions in meat products at high temperature. The generation of such harmful substances mainly depends on the heating temperature， heating time， heating method and the kind of meat. When heterocyclic amines are taken into the body and activated by cytochrome P450 enzymes， they are transformed into genotoxic metabolites by sulfotransferase and acetyl transferase. The main bioactive compounds contained in natural spices， such as phenols， amino acids， sugars and alkaloids， determine the final function of natural spices. Adding some natural spices into meat products can not only improve the final flavor of meat products， but also reduce the content of heterocyclic amines in meat products. In this paper， the inhibitory effects of Luzhou-flavor natural spices (Chinese cassia， clove， sweet basil， tarragon， coriander， star anise， nutmeg)， spicy natural spices (chilli， black pepper， prickly ash， lemongras， black mustard， ginger， garlic， onion， greater galanga， welsh onion) and light-flavor natural spices (turmeric， rosemary， kaempferia， tsao-ko， pomegranate seeds， cumin， licorice) on heterocyclic amines were introduced， the effective compounds in natural spices that have inhibitory effects on heterocyclic amines were elaborated， and the inhibitory mechanisms of these natural spices on heterocyclic amines were explained.

Abstract:Pectin and protein are the predominant natural biopolymers that are widely present in food systems.， The phase behavior of pectin-protein composite system can significantly affect the physicochemical properties， macro-structures & micro-structures of the final complex products. In this paper， we reviewed the formation mechanism of pectin-protein composite system and its application in food industry. Additionally， the effect of processing conditions on the characteristics of pectin-protein composite system is also discussed. Herein， we aimed to provide guidance for the design and development of pectin-protein complex products with special micro-structural characteristics and functions.

Abstract:A delivery system can enhance the solubility， stability and bioavailability of bioactive substances by encapsulating them and thus make it convenient application in the food， medicine， cosmetics and other fields. Emulsification solvent evaporation is a common method to prepare delivery carriers of active substances， its characteristics including use of mild conditions， ease of use and scale-up， lower residual solvent and so on. After introduction of emulsification solvent evaporation method， this paper summarizes the influence of material selection and preparation process on the delivery carriers， as well as the research progress on the application of this method in the delivery system， in order to promote further research and practical application of emulsification solvent evaporation method.

Abstract:The incidence of inflammatory bowel disease(IBD) is increasing globally. Epidemiological and clinical studies have found that diet affects the onset and treatment of IBD， and westernization of diet pattern is one of the important factors leading to the increase of IBD incidence. Reasonable dietary nutrition is very important for individual health， is one of the basic factors to reduce inflammation and maintain the normal operation of the immune system， and plays an important role in the prevention and treatment of diseases. At present， the clinical treatment of IBD is mainly drug therapy， which is mainly aimed at inducing and maintaining remission. In recent years， clinical studies have found that dietary intervention in patients with IBD can effectively relieve IBD symptoms and prevent disease recurrence. Dietary intervention has attracted more and more attention from researchers and clinicians because of its advantages such as low side effects， safety and economy. This paper summarizes the influence of dietary components on the onset and treatment of IBD， as well as the latest research progress on the role of dietary components and enteral nutrition in the treatment of IBD， recommends that IBD patients undergo nutritional risk screening and professional dietary consultation， and encourages IBD patients to pay attention to daily diet management and cultivate scientific and healthy eating habits. At the same time， in view of the limitations of the current diet intervention studies， the future research direction of IBD diet intervention was proposed to provide reference for clinical nutrition intervention and diet intervention studies of IBD.

Abstract:Meat products are rich in lipids and proteins， which are good for advanced glycation end products (AGEs). Research shows that AGEs can cause a variety of harm to human. Thus it is necessary to reduce the amount of AGEs produced during food processing. This paper introduces the formation， harm and detection of AGEs in foods， especially in meat products in recent years， aiming to provide new ideas for exploring new methods to reduce the production of AGEs in meat products processing.

Abstract:Human immunodeficiency virus(HIV) is a virus that causes defects in the human immune system. HIV can abnormally activate immune cells， greatly reduce CD4+T lymphocytes in the intestine， weaken the defense against pathogenic bacteria， make intestinal immune dysfunction， imbalance of intestinal flora， and cause other system abnormalities. In clinical practice， anti retroviral therapy(ART) is accompanied by diarrhea， nausea， allergy and other adverse reactions. In recent years， studies have found that the combination of probiotics and ART treatment can regulate intestinal flora， inhibit bacterial translocation， and reduce the inflammatory coefficient of HIV infected people. This article mainly summarizes the efficacy and mechanism of adjuvant treatment of HIV patients by supplementing a variety of probiotics after the intestinal microecological changes caused by HIV. It shows that dietary adjuvant treatment of HIV infection with probiotics has a positive effect and is an economic and feasible treatment method.

Abstract:Nanozymes with excellent broad-spectrum antibacterial properties provide a novel strategy to solve the problem of food spoilage caused by microorganisms. Nanozymes can catalyze the corresponding substrates to generate reactive oxygen species (ROS) in a physiological environment. At the same time， because of their simple preparation， low cost， high catalytic efficiency， easy large-scale production and high stability， they have broad applications in the field of food preservation prospect. Therefore， this review comprehensively summarizes the classification of nanozymes， including metal or metal oxide-based nanozymes， carbon-based nanozymes， polymer-based nanozymes， and other materials， and also elaborates on the main factors regulating the antibacterial activity of nanozymes (size， morphology， coating and modification， composition， etc.)， which provides effective guidance for how to design efficient antibacterial nanozymes. Most importantly， the unique application of nanozymes in food preservation， including the application of nanozyme-based antibacterial films and its application in the detection of bacterial contamination levels in food， is described in this paper. Due to its broad-spectrum antibacterial properties and negligible biotoxicity， antibacterial nanozymes can reduce the harm of microorganisms in the food industry， and help to control cross-contamination problems in food production and processing. Sustainable development is of great practical significance. All in all， antibacterial nanozymes are expected to become a novel antibacterial agent and/or strategy， and show broad application prospects in food preservation.

Abstract:Citrus is the largest fruit in the world and in China， and its fruits are rich in flavonoids. Citrus flavonoids possess various beneficial biological activities， including antioxidant， anti-inflammatory， lipid-lowering， anticancer， bacteriostatic， and neuroprotective properties， which contribute to human health. However， citrus flavonoids face challenges such as poor solubility， stability， and low bioavailability， which restrict their application in industrial production. The development of a stable encapsulation has emerged as an effective approach to overcome these limitations. This paper aims to provide a comprehensive review of the research progress regarding the structure， types， and main encapsulation methods for citrus flavonoids， which have been investigated and will be analyzed in terms of their advantages and disadvantages. The effects of citrus flavonoids encapsulation on physiological activities will be summed up. Additionally， the effects and application of encapsulation on the main citrus flavonoids(naringin， hesperidin， neohesperidin， etc) will be summarized. The findings are expected to provide theoretical basis for the high-value utilization of citrus flavonoids in functional food， cosmetics， pharmaceuticals， and other related industries.

Abstract:As consumer demand for high quality food products with fresh， non-additive properties increases， non-thermal food processing technologies are beginning to develop rapidly. High Pressure Homogenization (HPH) is a continuous non-thermal processing technology that ensures food safety while maintaining the organoleptic properties and nutritional value of the food. It is used to modify the texture of liquid foods and to kill micro-organisms through pressure， shear， collision， cavitation and heating， thus extending the shelf life of the food. In order to improve and apply HPH better， a detailed understanding of its mechanism of action and application is required. This paper reviews the research on the use of HPH in the sterilization， enzyme inactivation and color protection of fruit and vegetable juices to provide a theoretical basis for the application of HPH in the fruit and vegetable juice industry.

Abstract:β-lactoglobulin (β-LG) is an important natural active nutrient and one of the main allergens in bovine milk. β-lactoglobulin is about 50% of the total whey protein， is the major whey protein in bovine milk， has strong heat sensitivity and allergenicity， and plays a key role in the high-quality dairy industry， not only as an evaluation index of heat treatment intensity of milk， but also as the marker protein of milk allergens in food. Therefore， it is very important to effectively identify and detect bovine β-lactoglobulin. Thirteen variants of bovine β-lactoglobulin have been reported， of which A and B are the common variants whose content are the highest. According to different detection principles， the article briefly describes three kinds of detection methods of milk β-lactoglobulin variants in recent years， and summarizes the principles， advantages， disadvantages and some application examples of electrophoresis， chromatography and immunoassay. The two quantitative methods of liquid chromatography and capillary electrophoresis were introduced emphatically， and the future development direction of bovine β-lactoglobulin was prospected.

Abstract:Isinglass is a kind of edible and medicinal tonic， which has gained popularity due to its good efficacy in supplying collagen， beautifying health， regulating endocrine， enhancing immunity， etc. However， little efforts are made in relevant study on isinglass， especially the questions that user concerned about. In order to promote the sustainable development of isinglass industry in China， this paper describes the types and characteristics of the popular isinglass from retail market， main components， main functions， and the problems of developing isinglass industry， and proposes that it is necessary to enhance the study of isinglass about identification， classification， functions， quality standards， aiming to provide valuable references for researching the proper edible method and developing products of isinglass.