Abstract:Probiotics are highly valued in basic research， industrial transformation and clinical medicine for their effectiveness in maintaining intestinal health， regulating immunity and preventing and/or treating chronic diseases in humans. Benefiting from the increasing public awareness of probiotics， their products have become popular in daily consumption scenarios. Fermented dairy products， as an important product form for probiotics to exert health effects， have important application value because they combine the probiotic effect of strains with the health effects of dairy products. This paper took Lacticaseibacillus casei Zhang， a probiotic strain with far-reaching influence in both scientific evidence and industrial translation， as an example， and focused on its known probiotic properties and application in fermented dairy products to provide a theoretical basis for the subsequent in-depth analysis of the functional properties of this strain.

Abstract:The aim of the experiment was to calculate and analyze the physicochemical properties of three bitter peptides RK7， VN10 and SN12 identified in yak milk hard cheese using bioinformatics methods， and minimize the energy of the peptide structure. Obtained the X-ray diffraction three-dimensional structure of ACE protein crystals from the PDB database， and evaluated and characterized the ACE inhibitory activity of bitter peptides and the mechanism of action with ACE through molecular docking and database comparison. The instability indexes of RK7， VN10 and SN12 were 19.84， 49.44 and 42.87， respectively， and the hydrophobicities were 42.86%， 70.00% and 66.67%， respectively. These three peptides were molecularly docked with ACE， the results of the study showed that the Ala356， His387， Phe391， Pro407， His410， Glu411， Ser517， Val518， and Pro519 residues in the ACE molecule were important active sites for binding to RK7 and VN10， RK7， VN10 and SN12， respectively formed 3， 2 and 0 hydrogen bonds with the amino acids in the active site of ACE. The binding of RK7， VN10 and SN12 to ACE showed similar molecular mechanisms， all of which were bound in the active cavity of ACE(X: 35.46， Y: 43.15， Z: 55.47， R: 9 ?魡). The highest similarities between RK7， VN10 and SN12 and the known ACE inhibitor peptides in the BIOPEP database were 57.14%， 90.00% and 75.00%， respectively. Integrating the interaction of RK7， VN10 and SN12 with the amino acid residues of the active site of ACE and the BIOPEP database comparison results predicted the ACE inhibitory activity of the three peptides: VN10 > RK7 > SN12. Therefore， this experiment provided the reference for studying the ACE inhibitory activity of cheese bitter peptides at the theoretical and molecular levels.

Abstract:Objective: Enterococcus faecalis Gr17 is isolated from Chinese traditional fermented sour fish. It can be metabolized into a new broad-spectrum IIa bacteriocin enterocin Gr17， which has great application potential as a functional strain of fermented food. However， when the strain is used in the actual fermentation environment， it will inevitably face various stress conditions. Acid stress is one of the main stress factors. The purpose of this research was to investigate the effects of different acid stress conditions on the growth and bacteriocin biosynthesis of Gr17. Methods: On the basis of screening the acid stress parameters which could positively affect bacteriocin biosynthesis， the expression level of genes related to bacteriocin biosynthesis under the condition was determined and the influence mechanism was preliminarily analyzed. Results: The results showed that the cell density of Gr17 decreased with the decrease of pH value at the condition of pH 4.5~6.5 compared with the normal growth condition of pH 7.0. Under the condition of pH 5.0~6.5， the secretion and synthesis of bacteriocin was increased. Acid stress at pH 5.5 could significantly increase the secretion and synthesis of bacteriocin. Under these conditions， there was no significant change in the gene expression of ABC transport system associated with bacteriocin biosynthesis in as-48E， as-48F， as-48G and as-48H within 48 h of treatment. The expression of self-induced peptide gene entIP in quorum sensing regulation system increased significantly at 8 h. The expression of two-component genes entPK， entR and bacteriocin coding gene entGr17 increased obviously at 12 h. Conclusion: Based on the above results， it is speculated that acid stress at pH 5.5 could promote the secretion and expression of self-induced peptides， positively regulate quorum sensing system， thus increasing the synthesis of bacteriocin. The results of this study have important scientific and practical significance for revealing the regulation behavior of bacteriocin synthesis in the actual fermentation environment at the molecular level， and maximizing the application value of bacteriocin producing lactic acid bacteria in fermentation production.

Abstract:This study was analyzed the structure and characteristics of soy hull polysaccharide by ammonium sulfate graded， which used by molecular weight， monosaccharide composition， Fourier transform infrared spectroscopy(FT-IR)， scanning electron microscope (SEM)， atomic force microscope (AFM)， thermogravimetric analysis (TG) and rheological analysis. The study found that the water-extracted soy hull crude polysaccharide (WSHP) was mainly composed of galactose and mannose， while the polysaccharide fraction graded by 40% and 60% ammonium sulfate (ASHP40， ASHP60) was mainly composed of galactose and xylose. In addition， ASHP40 had the highest polysaccharide content， reaching 55.67%， and its relative molecular weight was lower than WSHP. The surface structure of ASHP40 and ASHP60 was loose， and ASHP60 had an obvious network structure. However， ammonium sulfate grading reduces the intermolecular interactions of polysaccharide components， resulting in low apparent viscosity and poor thermal stability. Therefore， this study proved that soy hull polysaccharides graded with ammonium sulfate had different compositions and microstructures， making these thermal stability and rheological properties significantly different.

Abstract:Objective: To establish a method for isolating and purifying actin from Dosidicus gigas myofibrillary protein and realize the batch preparation of actin. Method: The mixed protein of myofibrillar was extracted from Dosidicus gigas by phosphate buffer. The protein extracted from the squid was separated by anion exchange chromatography with only a small charge difference. Then the gel filtration chromatography was used to remove the small molecules in the mixture， such as desalination， and then purified by macromolecular protein purification. The purified protein was obtained with high purity (AC). SDS-PAGE， HPLC and MALDI-TOF-MS were used to identify the purity and molecular weight of the isolated protein. The particle size distribution of actin in the solution was characterized by light scattering technique. Results: In this paper， actin with high purity was extracted from myofibrillar protein， and the hydraulic radius(Rh) of actin was 3.46 nm. Conclusion: A new method for isolation and purification of actin in myofibrillar protein was preliminarily established， which provided support for the batch preparation of actin.

Abstract:The inhibitory effect of Lycium barbarum leaves flavonoids on pancreatic lipase activity was explored by enzyme kinetics. The interaction mechanism between them was studied by ultraviolet， fluorescence and infrared spectroscopy. The results demonstrated that the flavonoids had an inhibitory effect on pancreatic lipase activity with a half-inhibitory concentration (IC50) of (0.910±0.008) mg/mL， inhibition type was reversible and non-competitive inhibition， and the constant of inhibition was 6.04 mg/mL. Ultraviolet and fluorescence spectra revealed that the flavonoids could result in the exposure of aromatic amino acids of pancrelipase， the change of microenvironment and enzyme conformation， and quenching of endogenous fluorescence. The quenching type was mainly dynamic quenching mixed quenching. Thermodynamic parameters showed that the interaction force between them was mainly hydrophobic force. Infrared spectroscopy revealed that the effect of the flavonoids on the secondary structure of enzyme protein was mainly as follows: the structure of the compound became orderly， and the β-sheet was transformed to α-helix. The flavonoids could change the structure and microenvironment of pancrelipase and then inhibit its activity.

Abstract:In order to investigate the effects of Cl- and citrus flavonoids on pancreatic amylase activity and starch digestion in vitro， the effect of Cl- on the enzymatic properties of pancreatic amylase was studied by DNS method， and the effects of citrus flavonoids on pancreatic amylase activity and starch digestion were studied with or without Cl-， and the interaction mechanism of Cl- and citrus flavonoids with pancreatic amylase was studied by fluorescence spectrometry. The results showed that Cl- was an activator of pancreatic amylase， and the activation showed a dose-dependent effect. 10 mmol/L Cl- (equivalent to the salt intake of 4.5 g/d) could fully activate pancreatic amylase. Cl- could increase the optimum temperature(from 37 ℃ to 47 ℃) and thermal stability (inactivation temperature increased from 47 ℃ to 57 ℃)， and change the optimal pH (from 6 to 7) of pancreatic amylase without changing its pH stability. In the absence of Cl-， high concentration of flavonoids had inhibitory effect on pancreatic amylase， with the highest inhibition rate 17.1%， but 10 mmol/L Cl- could relieve the inhibition. 10 mmol/L Cl- could significantly increase the starch digestion rate， and citrus flavonoids of final mass concentration 0.056 mg/mL had no effect on starch digestion. The results of fluorescence spectrum experiment showed that the fluorescence of pancreatic amylase was statically quenched by binding citrus flavonoids， and 10 mmol/L Cl- had no effect on the fluorescence spectrum of pancreatic amylase interaction with citrus flavonoids. The results of this study can provide reference for starch digestion in vitro and the development of citrus flavonoid functional food.

Abstract:Ten kinds of common sulfide flavors were selected and their inhibitory ability on Staphylococcus aureus and Listeria monocytogenes was investigated by measuring the diameter of inhibition zone. The relationship between the structure of sulfide flavors and the antibacterial ability was also analyzed. The sulfide flavor with the strongest antibacterial activity was selected and its effect on the expression of nuc gene in Staphylococcus aureus was investigated by qRT-PCR. The results showed that diallyl disulfide (DADS)， methyl furfuryl disulfide (MFDs) and allyl sulfide (DAS) had good antibacterial effects on two Gram-positive bacteria， and the antibacterial activity was DADS > MFDS > DAS. Among the 10 kinds of sulfide flavors， DADS had the strongest antibacterial activity， and the minimum inhibitory concentration (MIC) of DADS against S. aureus and L. monocytogenes were 312.5 mmol/L and 1.25 mol/L， respectively. At the subinhibitory concentrations (1/16 MIC， 1/8 MIC， 1/4 MIC and 1/2 MIC)， DADS significantly decreased the expression level of nuc gene in S. aureus (P＜0.01). These results indicated that allyl and disulfide bonds could enhance the antibacterial activity of sulfide flvors and play an important role in inhibiting the virulence of S. aureus.

Abstract:To study the effects of lotus seedpod oligomeric procyanidins(LSOPC) on tissue damage and intestinal microflora disorder in mice induced by advanced glycation end products (AGEs)， healthy male mice as animal model were divided into 4 groups and fed 12 weeks with high AGEs AIN-93G， high AGEs AIN-93G added 0.2% or 0.5% LSOPC (w/w)， and normal AIN-93G as the control group. The effects of AGEs and LSOPC on mice weight， diet， water intake， organs indexs， intestinal tissue damage， colonic tight junction proteins and oligopeptide transporter expression， intestinal inflammatory factor and intestinal microflora disorder were analysis. Our results showed that both 0.2% LSOPC and 0.5% LSOPC had obvious ameliorative effects on tissue injury， increased the expression of ZO-1 and occludin， and decreased the expression of Pept1， TNF-α， IL-6， VCAM-1 and ICAM-1. Intestinal environment and intestinal microbial disorder were also significantly improved， which were dose-dependent on LSOPC. Conclusion: LSOPC could reduce mice tissue damage and intestinal microflora disorder caused by dietary AGEs， and has the potential to develop into a basic dietary supplement.

Abstract:DNA vaccine has brought new hope to tumor immunotherapy， and appropriate adjuvants can further improve the immune effect of it. In this study， the polysaccharides extracted from pleat， stem and cap of Ganoderma lucidum were isolated. The immune function promoting effects of the polysaccharides from different parts were investigated in mice model. Then the faciliting ability of the Ganoderma lucidum polysaccharide on tumor immunotherapy effect of HER2/neu plasmid DNA vaccine were investigated with the ignificant immune promoting polysaccharide. 4T1 tumor bearing mice were divided into control group， DNA vaccine group and Ganoderma lucidum polysaccharide group. Ganoderma lucidum polysaccharide group were given 30 mg/kg Ganoderma lucidum polysaccharide for 3 days before subcutaneous injection of DNA vaccine twice. After 21 days， the tumor size and weight of mice were measured. Compared with DNA vaccine group and control group， the tumor growth of polysaccharide group was significantly inhibited and the weight growth was stable. T cell phenotype and its subtype analysis showed that Ganoderma lucidum polysaccharide could significantly promote the cellular immune response of mice to HER2/neu plasmid DNA vaccine. This study will provide a theoretical reference for the development of DNA vaccine adjuvants.

Abstract:Objective: To explore the regulation of fucoidan (FUC) as a functional food on immune function and intestinal flora in immunocompromised mice. Methods: Forty male BABL/C mice were randomly divided into 4 groups. The intervention group was given high and low doses of fucoidan for intragastric intervention every day for 28 consecutive days. The control group and model group were given equal volume of normal saline every day. Except for the normal group， the other groups were intraperitoneally injected with cyclophosphamide on the 24th day to construct an immunocompromised mouse model. Enzyme-linked immunosorbent assay， flow cytometry， HE staining， high-throughput sequencing of 16S rRNA gene of intestinal microbiota， etc. were used to detect the changes of mouse immune function and intestinal flora. Results: Compared with the normal group of mice， the immune function of the model group was significantly decreased， and the spleen and intestinal tissues were severely damaged. After FUC intervention， the morphological damage of the spleen and colon tissues was significantly improved (P<0.05). At the same time， FUC alleviated the increase of inflammatory factor levels in serum (P<0.05). Besides， the content of Bacteroides in the cecal content of the model group mice was significantly increased (P<0.05)， Lactobacillus and Roseburia were significant decrease (P<0.05) compared with the normal group. After FUC intervention， the imbalanced intestinal flora was restored in model mice， and the composition structure of intestinal flora was approached the normal group. Conclusion: FUC can effectively improve the immune function and alleviate the intestinal mucosal damage in immunocompromised mice. The mechanism may be related to the change of intestinal flora.

Abstract:Objective: To evaluate the immune function of compound astaxanthin. Methods: Splenic lymphocyte transformation test of mice induced by ConA， delayed ear swelling test of mice induced by DNFB， antibody generation cell count test， serum hemolysin generation test， carbon particle clearance test and NK cell activity test were used to comprehensively evaluate the immune-enhancing function of compound astaxanthin. Results: Compared with the solvent control group， astaxanthin oil and compound astaxanthin could significantly improve the proliferation level of splenic lymphocytes and delayed ear edema in mice， and the cellular immune function was positive， and the activity of compound astaxanthin was better than astaxanthin oil. The hemolytic plaque number and serum antibody level were significantly increased， the humoral immune function was positive， and the activity of compound astaxanthin was better than astaxanthin oil. There was no significant effect on carbon clearance and NK cell activity in mice， and the results of mononuclear macrophage function and NK cell activity were negative. Conclusion: The compound astaxanthin has the function of enhancing immunity.

Abstract:Objective: Astaxanthin is a carotenoid found abundantly in marine foods， and its antioxidant properties are widely recognized. In recent years， the impact of oxidative stress on Alzheimer's disease(AD) has attracted more and more attention. Previous studies mainly focused on the use of astaxanthin's antioxidant effect to delay its pathological progress after the onset of AD. The aim of the present study was to explore the preventive effect of astaxanthin on AD using a rapid aging mouse model. Methods: Male SAMP8 mice were randomly divided into two groups， including control group and astaxanthin group(n=8). SAMR1 mice was used as the control group. The mice in astaxanthin group were supplemented with 40 mg/kg bw astaxanthin for 4 months. Morris water maze and open-field test were conducted to evaluate the ability of learning and memory as well as the anxiety of mice. The content of Aβ and level of oxidative stress in the brain， liver and serum were also measured. Results: Dietary astaxanthin significantly enhanced the ability of learning and memory as well as relieved the anxiety of SAMP8 mice. Moreover， astaxanthin significantly reduced the content of Aβ and impoved the level of oxidative stress in the brain. Meanwhile， dietry supplementation with astaxanthin exerted different extent of antioxidant level in the liver and serum. Conclusion: Dietary astaxanthin enhanced the ability of learning and memory by inhibiting oxidative stress in the brain and tissues of SAMP 8 mice， which might prevent or delay the occurrence of AD. These results provide a theoretical basis for exploring the neuroprotective function of astaxanthin and its application in related functional foods or dietary supplements.

Abstract:Objective: To establish a model of weaning human floral-associated mice and study on the effect of intestinal flora on the grouth and development of mice. Methods: The intestinal flora of weaned infants was transplanted into germ free Kunming mice to establish a model of weaning human floral-associated mice. Weaning mice with human flora and germ free mice (n=9， for each group) were fed with basic diet until 8 weeks old. The body weight， brain fatty acid content， insulin-like growth factor-1 (IGF-1) and in-sulin-like growth factor binding protein-3 (IGFBP3) contents in serum and liver were measured. The development of hippocampal CA1 area and colon were observed by HE staining. The differences of indexes between the two groups were compared， and the effects of intestinal flora on brain， intestinal development and immunity were analyzed. Results: The weaning human floral-associated mice were in good health and could partially simulate the intestinal flora of weaning infants. Intestinal flora had significant effects on the development of mice brain neuronal cells， synapses and colonic villi. The contents of monounsaturated fatty acids C16∶1(P < 0.001)， C18∶1 (P < 0.01) and polyunsaturated fatty acids C18∶3 (P < 0.05)， C20∶3 (P < 0.01)， C20∶4 (P < 0.001)， C22∶5 (P < 0.05) and C22∶6 (P < 0.01) in mouse brain were significantly affected. It had a significant effect on the content of IGF-1 in serum and liver of mice. Conclusion: The weaning human floral-associated mice provides an effective animal model for the study of the effect of intestinal flora on host physiological function in weaning infants.

Abstract:To study the effects of infant formula supplemented with α-lactalbumin and tryptophan on brain development in newborn rats， this study used 30 SD rats at 7 days of age as experimental object， randomly divided into 3 groups， rat breast feeding group (ck)， the common infant formula feeding group and upgrade infant formula feeding， mixed feeding after 21 days. The effects of upgraded infant formula on brain development of newborn rats were investigated by measuring growth and development indexes， nerve function and intestinal microflora of rats. The results showed that upgrading infant formula could restore the abundance of intestinal flora at the genus level， significantly increased the content of beneficial bacteria AKK， and contributed to the establishment of a good intestinal flora. It could significantly increase the concentration of 5-HT and its metabolites in serum and diencephalon of rats， and promote neural development. Conclusions: Upgraded infant formula supplemented with α-lactalbumin and tryptophan could significantly increase the abundance of intestinal beneficial bacteria and the concentration of 5-HT and its metabolites in serum and diencephalon tissues of newborn rats， with potential health benefits for intestinal and neural development. This study could provide theoretical basis and scientific support for the upgrading of infant formula milk powder.

Abstract:s A variety of chronic diseases are attributed to oxidative stress induced by imbalance of free radical reaction. Spirulina polysaccharides(PSPs) are natural active substances with strong antioxidant， but its mechanisms of antioxidant and anti-aging are still unclear. In the current study， the antioxidant activity of PSPs in vitro was determined by chemical methods， and the resistance of PSPs to oxidative stress of Caenorhabditis elegans (C. elegans) was tested in vivo. The results showed that PSPs had DPPH· scavenging capacity and total reducing power promoting capacity， which was dose-dependent. PSPs prolonged the life span of C. elegans in a dose-dependent manner. The antioxidant capacity was enhanced by improving the exercise abilities and the activities of antioxidant enzymes SOD and CAT， reducing the accumulation of senescence pigment and the level of intracellular reactive oxygen species (ROS). Under the oxidative stress of 1‰ H2O₂， PSPs significantly prolonged the life span of C. elegans. The qRT-PCR results indicated that PSPs could significantly up-regulate the mRNA expression of daf-16， skn-1， and sir-2.1 genes. These results suggested that PSPs could enhance the resistance to oxidative stress and prolong the life span of C. elegans by increasing the activity of antioxidant enzymes and the expression of related genes through the insulin signaling pathway.

Abstract:Yeast β-glucan has attracted much attention due to its good biological activity， but its low solubility limits its application. In order to improve the solubility of β-glucan and expand its application range， the effects of enzyme dosage， substrate concentration， temperature and time on the yield of water-soluble β-glucan were investigated. The process was optimized by response surface methodology. The functional properties and structural changes of β-glucan before and after enzymatic hydrolysis were compared. The results showed that the yield of water-soluble β-glucan was 56.12% under the conditions of enzyme dosage 4.30%， substrate mass concentration 15 mg/mL， enzymolysis temperature 45 ℃， enzymolysis time 83 min. The solubility of the product was reached 89.74%， the molecular weight was decreased to 2.99×106， 6.88×104 u and 1.40×104 u， D[4，3] was decreased from 67.49 μm to 38.25 μm， and the thermal stability was improved. The structure of β-glucan remained unchanged， which was still connected with β-1，3-glycoside bond. Circular dichroism chromatography showed that the asymmetry of water-soluble β-glucan was increased and the structure was highly ordered. Scanning electron microscope showed that the yeast β-glucan was changed from intact granules to irregular slice shape.

Abstract:Peony swallow is the first signature dish in shui xi of Luoyang. However， the production process is complicated. This paper took drying time， energy consumption， VC content， shrinkage and rehydration as experimental indexes to investigate the influence of saturated steap-heat pump combination drying on the drying characteristics of white radish， the main ingredient of Peony Swallow. The results showed that the drying rate and drying time could be improved obviously by lengthening the treatment time of saturated steam and increasing the number of treatment times. The drying time of white radish dried by the combination of saturated steam and heat pump was reduced by 10%-45% than that of heat pump， and the drying energy consumption was reduced by 13.67%-44.53%. The quality of dried radish products was the best when the combination of saturated steam (treated twice， 6-8 min each time) and heat pump was used. The VC content， rehydration ratio， whiteness， hardness and masticability were 50.22 mg/100 g， 4.03， 63.36， 5 457.90 and 2 829.68 g， respectively. Under this condition， white radish dry products aroma was pure， pungent flavor was light， texture was soft and smooth， edible quality was best. The experiment proved that saturated steam treatment could significantly increase the drying rate of white radish and improve its quality， which was suitable for application in the processing of peony swallow.

Abstract:In order to further study the effect of heat moisture treatment on the edible quality of sweet potato vermicelli， on the basis of previous research， the breakage rate (BR)， resistance to extension (RTE) and digestibility of vermicelli [rapid digestible starch (RDS)， slowly digestible starch (SDS)， and resistant starch (RS)] content were used as the quality evaluation indicators of vermicelli. The single factor test and the Box-Behnken test design model in the response surface method were used to optimize the heat moisture treatment conditions of sweet potato starch. The results showed that the water content of starch and the time of heat moisture treatment had an extremely significant effect on the quality of sweet potato vermicelli (P＜0.01)， and the temperature of heat moisture treatment had a significant effect on the quality of sweet potato vermicelli (P＜0.05). The best heat moisture treatment conditions were temperature 95 ℃， water content of starch 26%， time 1 h. Under these conditions， the BR of the sweet potato vermicelli was 3.33%， the RTE was 162.25 g， the dry basis RDS was 25.83%， the SDS was 27.07%， and the RS was 45.38%. Compared to the original sweet potato starch vermicelli， the BR， RDS and SDS of the optimal conditions heat moisture treatment sweet potato starch vermicelli were respectively reduced by 33.33%， 29.94% and 31.78%， the RTE and RS respectively increased by 60.27% and 108.84%. The replicated stable results proved that the conditions were reasonable and feasible， and the research results provided a theoretical basis for improving the taste and nutritional value of sweet potato vermicelli by heat moisture treatment.

Abstract:The effects of the microwave-assisted preparation of nano fish bone calcium from tuna with different additive amount and 0.2% calcium chloride on the gel quality of surimi were determined. The results showed nano fish bone calcium which compared with 0.2% calcium chloride had more advantages in gel strength， texture， water holding capacity and protein intermolecular force of surimi products， although the activity of Ca2+-ATPase was not as good as 0.2% calcium chloride. Both had no influence on the pH and whiteness values of surimi gels. The results of SDS-PAGE and Fourier infrared indicated that Ca2+ activated endogenous transglutaminase(TGase) to strengthen the covalent cross-linking of amino acid residued to form more β-sheet protein structures， thereby strengthening the strength of surimi gel. So nano-fish bone calcium could not only provide minerals and trace elements required by the human body， but also strengthen the physical and chemical properties of surimi， and could be used as an ideal natural calcium source in functional foods or as a food supplement.

Abstract:In this paper， the extraction technology and bioactivity of polyphenols from sweet potato leaves were studied. Prior to single factor research， the Box-Behnken experimental design combined with response surface modeling were used to optimize the extraction condition for polyphenols from sweet potato leaves. Four independent variables were tested for the response surface experiment， including volume fraction of ethanol (A)， temperature (B)， solid-liquid ratio (C)， and extraction time(D). The main components of polyphenols in sweet potato leaves were determined by HPLC. Antioxidant activity of polyphenols from sweet potato leaves was evaluated by scavenging DPPH free radicals and FRAP method. The inhibition assays of polyphenols from sweet potato leaves on α-amylase and α-glucosidase were evaluated in vitro. The optimal extraction condition was determined to be as follows: volume fraction of ethanol 88%， temperature 57 ℃， solid-liquid ratio 1 ∶ 20， extraction time 30 min. The extraction efficiency of polyphenols in sweet potato leaves was (15.34 ± 0.19) mg GAE/g. The main polyphenols of sweet potato leaves were 5-caffeoylquinic acid， 3-caffeoylquinic acid， 4-caffeoylquinic acid， 3，4-caffeoylquinic acid， 3，5-caffeoylquinic acid， 4，5-caffeoylquinic acid and 3，4，5-caffeoylquinic acid. The results of antioxidant activity and in vitro anti-diabetic assays showed that the polyphenols from sweet potato leaves had substantial effect on antioxidant and anti-diabetic activity. The DPPH free radical scavenging capacity and FRAP total antioxidant capacity were 11.57 mg TE/g and 12.30 mg TE/g， respectively. The inhibitory activities of polyphenols from sweet potato leaves towards α-amylase and α-glucosidase were 89.94% and 22.28%， respectively.

Abstract:Based on the results of sensory evaluation， single factor test was used to determine the koji making strains and the formula of raw materials for good flavor. The results showed that when koji-making strains were Aspergillus oryzae and Saccharomyces cerevisiae， raw materials were 80% egg liquid and 20% black bean powder， the flavor of koji was the best， and it had olive and vegetable flavor and slight salted egg yolk flavor. The time of steaming， the moisture content and the time of koji making were selected as independent variables， the activity of protease was taken as an index， Box-Behnken was used to optimize the koji-making process. The results showed that when the steaming egg curd time was 41 min， the moisture content in egg curd was 66.1%， and the koji ferment time was 50 h， the highest protease activity in egg koji was 5 797 U/g. The study has found a feasible scheme for the development of egg sauce products.

Abstract:In order to improve the stability of loquat flower polyphenols， bovine serum albumin (BSA) and ι-carrageenan were used as wall materials to prepare loquat flower polyphenols nanoparticles by heat treatment. Single factor test and response surface methodology were employed to optimize the preparation process based on the embedding rate of polyphenols. The characteristics of nanoparticles prepared under the optimal preparation process were studied. The results showed that both polyphenol content and DPPH· scavenging activity of ethyl acetate extract of loquat flower alcohol extract were higher than that of other organic solvent extract， and it was used as core material. The optimal preparation process was as follows: the pH of PBS was 6.6， the mass ratio of ι-carrageenan to BSA was 4 ∶ 15， the mass ratio of BSA to core was 15 ∶ 1， the mass concentration of BSA was 1 mg/mL， the temperature of heat treatment was 80 ℃， the embedding rate of polyphenols under this condition was (82.12±0.48)%. The average particle size of polyphenol nanoparticles was (126.0±5.38) nm， the polymer dispersity index (PDI) was 0.43±0.02， the Zeta potential was (-31.1±0.42) mV. Analysis of scanning electron microscope showed that the particles were spherical. The DPPH· scavenging activity of loquat flower polyphenols could be preserved better by embedding treatment， and the stability was stronger.

Abstract:Objective: The effects of different wall materials on the preparation of Bifidobacterium lactis Probio-M8 microcapsules by vacuum low-temperature spray drying were studied in this study. Method: The solubility， rehydration time， powder fluidity， and the physical properties of the powder moisture and water activity of the microcapsule powder with different wall materials were measured by physical methods， and the changes in the integrity of the bacterial cell membrane before and after drying were observed using a fluorescence microscope. The morphology and structure of the microcapsule powder were observed by scanning electron microscope and the glass transition temperature of the microcapsule powder was measured with a differential scanning calorimeter. The DPPH free radical scavenging ability and total antioxidant capacity of different wall materials to protect the bacteria were measured. Results: The Probio-M8 microcapsule powder of composite wall material showed a higher survival rate of 73.8%， and had a lower water content(4.85%) and water activity(0.17)， and the powder had excellent fluidity. But due to the complex composition of the composite wall material， the microcapsule powder of the composite wall material had lower solubility and longer rehydration time than the three kinds of microcapsule powders. In addition， the integrity of the Probio-M8 cell membrane protected by the composite wall material was also higher than that of the Probio-M8 protected by the other three wall materials， which effectively protects the integrity of the bacterial cell membrane. Furthermore， the Probio-M8 microcapsule powder of composite wall material had a higher glass transition temperature and a higher glass transition temperature and strong antioxidant capacity which is beneficial to the storage stability of Probio-M8 microcapsule powder. Conclusion: This experiment compared the effects of different wall materials on the bacterial activity after spray drying of Probio-M8， and found that different wall materials have different protective effects on the bacterial cells. Among them， the composite wall material can protect the bacterial cells more effectively. Which has certain reference significance for the industrial production of Bifidobacterium lactis Probio-M8 microcapsules.

Abstract:In order to improve the paper's poor mechanical properties， poor hydrophobicity and weak bacteriostasis in food packaging， food packaging paper was prepared by compounding polylactic acid and nano-zinc oxide using a coating process. The performance of packaging paper for food was evaluated by indicators such as tensile strength， water contact angle and antibacterial， and the paper was applied to fresh pork preservation. The results showed that the samples of the blank group and the control group had deteriorated in the 6th day of refrigeration time， while the test group still maintained good quality， and the samples of this group were not completely deteriorated until the 10th day. It showed that the food packaging paper could effectively inhibit the activity of bacteria， maintain a better color of fresh meat， and could significantly reduce the juice loss rate of fresh meat， and better maintain the sensory quality of fresh meat， thereby extending the shelf life of fresh meat. Compared with the untreated food wrapping paper， the hydrophobic antibacterial food wrapping paper had better fresh-keeping effect.

Abstract:Malondialdehyde (MDA)， 4-hydroxy-2-nonenal (HNE) and 4-hydroxy-2-hexenal (HHE) are three typical non-volatile aldehydes， which are genotoxic and closely related to the oxidation of polyunsaturated fatty acids(PUFA). They are common in vegetable oils and oil-based foods. However， there are few studies on their formation and correlation with oil quality. In this paper， five common commercial vegetable oils in China were selected as the research objects， and the formation rules of MDA， HHE and HNE in the simulated storage process of vegetable oils were explored by Schaal accelerated oxidation method. Combined with chemometrics method， the application scope of the three as evaluation indexes of oil oxidation was explored. The results showed that the contents of three aldehydes increased gradually during 30 days storage at 60 ℃， and the formation and distribution of aldehydes in different vegetable oils were significantly different (P<0.05). MDA and HNE were detected in all tested vegetable oils. The content of MDA in linseed oil (LO) was the highest [(3.34±0.06) μg/g]， while more HNE was produced in corn oil (CO)， rapeseed oil (RO) and linseed oil (LO)， with the contents of (3.70±0.08)， (1.60±0.04) μg/g and (1.91±0.06) μg/g， respectively. HHE was only detected in rapeseed oil (RO) and linseed oil (LO)， and the content of HHE in linseed oil (LO) was the highest [(4.46±0.07) μg/g]. Principal component analysis was used to study the correlation between three aldehydes and traditional oxidation indexes. The results showed that the correlation between MDA content and oxidation indexes was poor in oils with low PUFA content， while HNE and HHE had high correlation with oxidation indexes， which could be used as new evaluation indexes of oil oxidation.

Abstract:In order to study the effect of micro-environmental modified atmosphere on bluberries during storage， micro-environmental modified atmosphere package (mMAP)， 1-methylcyclopropene (1-MCP) and micro-environmental modified atmosphere package combined with 1-methylcyclopropene (mMAP+1-MCP) were used to treat bluberries， and the untreated blueberries were used as control. The blueberries after treated were stored in cold storage (-0.5 ± 0.3) ℃， and fruit firmness， contents of cell wall polysaccharide， activities of cell wall degrading enzyme and key degrading enzyme gene expression were measured at 0， 20， 40 and 60 day during storage. The results showed that the three treatments could significantly reduce the soft fruit rate compared with the control group (P < 0.05)， and the effect of mMAP + 1-MCP treatment was the best. The fruit firmness of mMAP + 1-MCP treatment was significantly higher than other treatments(P < 0.05)， with higher content of cellulose and protopectin. The hemicellulose of it was higher than other treatments in the early stage of storage while the soluble pectin content remained lower in the early and medium stage. According to the analysis of cell wall degrading enzymes， the activities of cellulase(Cx)， polygalacturonases (PG) and pectinmethylesterases (PME) of mMAP+1-MCP treatment group were the lowest at 40 day of storage， and the activities of β-galactosidase (β-Gal) and α-L-arabinofuranosidase (α-Af) of mMAP+1-MCP treatment were significantly (P < 0.05) lower than those of other treatments during 60 day. Orthogonal partial least squares discriminant analysis (OPLS-DA) showed that the differences between mMAP+1-MCP treatment and other treatments were Cx and β-Gal， the expression of the two key cell wall degrading enzymes was analyzed and the results showed that mMAP+1-MCP treatment could effectively delay the time which peak value occurs of Cx and β-Gal genes during storage of blueberries. Therefore， the mMAP+1-MCP treatment could delay the time which peak value occurs of the gene expression of Cx and β-Gal and inhibit the activities of Cx and β-Gal in the late stage of storage， maintaining the contents of cellulose and pectin， and then slow down the softening of fruits.

Abstract:The purpose of this study was to investigate the antibacterial activity of single and compound bacteriostatic agents against specific spoilage organisms(Proteus vulgaris and Hafnia alvei) isolated from lightly salted large yellow croaker. In this study， the minimum inhibitory concentration of chitosan on specific spoilage organisms was detected， and then， the sub-inhibitory concentration of chitosan and the addition of different concentrations of nisin were used to treat the fish juice. And the two bacteria were respectively inoculated into the fish juice and stored at 5 ℃. The extracellular products and spoilage indexes were used to evaluate the inhibitory effect of different treatment groups on the two bacteria. The results showed that the minimum inhibitory concentration of chitosan against Proteus vulgaris and Hafnia alvei were 125 μg/mL. When the mass concentration of chitosan in fish juice was the sub-inhibitory mass concentration (62.5 μg/mL)， the higher the mass concentration of composite nisin was the stronger the inhibition effect. According to the total number of colonies， the optimal synergistic combination for Proteus vulgaris and Hafnia alvei was chitosan 62.5 μg/mL and nisin 1 000 μg/mL. Compared with single chitosan， compound bacteriostatic agent had better effect(P<0.05)， the combination of chitosan and nisin showed synergistic antibacterial effect. The results of this study provide basic research for targeted inhibition of bacteria and shelf life extension of lightly-salted large yellow croaker.

Abstract:Ultra high-temperature technology plays an important role in the process of milk from precious food to common food. With the improvement of consumption level and health consciousness， milk consumption has increased year by year in China， while the consumption of imported milk has also risen accordingly due to dairy events in recent years. The concept that ′imported milk is of a better quality than domestic′ prevails. In this experiment， solid-phase microextraction (SPME) combined with gas chromatography (GC) -mass spectrum (MS) technology was used to perform qualitative and quantitative analysis of volatile compounds in domestic and imported milk. It was shown that imported milk contains high concentrations of ketones， acids， and sulfur compounds. Among these compounds， the concentrations of 2-heptanone， 2-nonanone， and 2-undecanone in imported milk samples were about two times higher than domestic samples. Besides， combined with intelligent sensory and quantitative descriptive analysis， the overall odor and taste of imported milk and domestic milk were evaluated(1-7 scores system). Domestic milk samples had similar sensory profiles with strong milk flavor and milk fat flavor， the off-flavors (cowy， metallic and green flavor) and the cooking flavor were weak. Besides， the overall preference scores of domestic milk samples were the highest， which are 5.8 and 5.9 scores， respectively. The milk and fat flavors of imported milk samples were relatively weak and the off-flavors were relatively strong， and the overall preference scores were less than 4.0.

Abstract:In order to study the changes of microbial community and volatile flavor components during the production of fermented sausages， high-throughput sequencing technology was used to analyze the V3-V4 regions of bacterial 16S rDNA at different stages， and gas chromatography-ion mobility chromatography(GC-IMS) was used to analyze the volatile flavor components. The results showed that the microbial community structure and relative abundance of samples at different fermentation stages were different. In the fermentation process， Lactobacillaceae always dominate， followed by Staphylococcus， Brevibacterium. Staphylococcus increased to the highest at 12 h(26.83%)； unspecified Lactobacillaceae reached the highest relative abundance at 30 h (92.81%). In the earlier stage of fermentation， volatile flavor components were dominated by aldehydes and ketones， and esters gradually increased in the middle of fermentation， and 1-octen-3-ol and trimethylpyrazine reached their peaks in the later stage. Pearson correlation analysis indicated that unspecified Lactobacillaceae was closely related to the synthesis of 1-octen-3-ol， trimethylpyrazine， ethyl acetate， hexanal， octanal and 2-butanone and other flavor substances， and Staphylococcus and Flavobacterium were positively correlated with the synthesis of 2-methylbutanal and 3-methylbutanal. The combination of high-throughput sequencing and GC-IMS could comprehensively analyze the bacterial succession and volatile aroma component changes of fermented sausages， providing scientific support for the quality improvement of fermented sausages.

Abstract:In this study， Lactobacillus plantarum L1 and Lactobacillus fermentum L2 were selected as inoculated strains to ferment elderberry powder to make fermented juice. The changes of pH value， total acid， color difference value， anthocyanin content， total phenol and total flavone content， superoxide anion scavenging activity， total reduction capacity， and volatile flavor compounds before and after fermentation were determined. The results showed that during the fermentation period， the pH value of elderberry juice decreased but the total acid increased significantly. The L* value and a* value increased first and then decreased， and the b* value was relatively stable. The anthocyanin content decreased， but the total phenol and total flavonoids content increased. The superoxide anion scavenging rate and total reduction capacity increased by 82.07% and 55.27%， respectively. A total of 99 volatile flavor compounds were detected among the uninoculated samples and fermented juice samples before and after fermentation. The results showed that there were significant differences in flavor characteristics among three samples by principal component analysis. In conclusion， the nutritional value， antioxidant capacity and flavor quality of elderberry juice can be improved by lactic acid bacteria fermentation.

Abstract:Chungui (CG) variety is a new oolong tea suitable variety bred by using single plant breeding method. To explore the characteristic aroma and taste quality of CG oolong tea， the HS-SPME coupled with GC×GC-TOF-MS and UHPLC-Q-TOF-MS non targeted metabonomics technique were used to investigate the volatile and non-volatile components of CG oolong tea and Tieguanyin(TGY) oolong tea. The results showed that the volatile aroma components were close to TGY oolong tea. Indole accounted for 10.34% of the total volatile components in CG oolong tea， and the important volatile components such as indoles， nerolidol and jasmine lactone were significantly higher than TGY oolong tea. CG non-volatile components were showed grate difference between TGY oolong tea. The monomer or dimer catechins such as EC， ECG and procyanidin B1 in CG oolong tea were significantly lower than that in TGY oolong tea. However， flavonols or flavonoid glycosides which share the same precursors with catechins， γ-aminobutyric acid， glutamate and theanine glycosidase were significantly higher than that of TGY oolong tea. The relative contents of tryptophan was significantly lower than TGY oolong tea， this may be related to indole concentration in spring best oolong tea. These metabolites constitute the characteristics of lasting flower fragrance and mellow tea soup of CG oolong tea.

Abstract:In order to study the release behavior of limonene， a characteristic aroma component of tangerine peel， a purge and trap-gas chromatography/mass spectrometry (P & T-GC/MS) method was established to analyze the content of limonene in tangerine peel. Based on this method， the limonene was investigated at different temperatures. The release behavior of tangerine peel was fitted with dynamic models (zero-level model， first-level model， Higuchi model) to obtain suitable kinetic models and parameters. The results showed that: 1) The detection method based on the P & T-GC/MS combined technology had good linearity in the range of 0.06-0.30 μg/mL， the detection limit was 0.020 μg/mL， and the recovery of limonene was between 96.97% and 126.71%. The precision was 1.19%-4.70% (n = 5). 2) At each test temperature， the amount of limonene released in the sample increased with time， and the overall trend increased first and then slowly. 0-10 min， the overall release amount of limonene in the sample was higher， and the release rate was faster. 10-20 min， the release rate of limonene in the sample was significantly reduced. 20-65 min， the limonene in the sample was basically no longer released. 3) The first-order release model could better describe the release behavior of limonene in samples at different temperatures. The model fitting correlation coefficient R2 was between 0.906 and 0.997， and the activation energy of limonene release was 31.71 kJ/mol.

Abstract:Objective: In this study， endophytic fungi from wild Glycyrrhiza uralensis Fisch were isolated and the antibacterial and antioxidant activities of their secondary metabolites were evaluated. Method: Using fresh wild licorice as material， the different tissue parts of licorice were treated by tissue cutting method， and then the endophytic fungi were separated and purified with 9 different media and carry out molecular biological identification. The antimicrobial activities of their metabolites against five tested strains was evaluated by paper diffusion method. The antioxidant activity of the metabolites was evaluated by DPPH and ·OH radical scavenging capacity. Results: 128 strains of fungi were isolated from the plant licorice， which belonged to 5 different genera through molecular biology identification. YS-6 fermentation broth showed certain antibacterial activity against Staphylococcus aureus. The DPPH free radical scavenging rate of GS-6a fermentation broth was 97.54%， and the ·OH free radical scavenging rate of GS-6a mycelium was 98.83%. Conclusion: The resources of endophytic fungi isolated from licorice are abundant and diverse， which are good sources for screening antibacterial and antioxidant substances.

Abstract:Microcysin (MC)， as one of the most toxic hepatoxins， is often detected in polluted water bodies， which seriously threatens the safety of drinking water for humans and animals. It is very important to develop its rapid detection methods. In the previous study， an anti-MC-LR phage display nanobody library was successfully constructed. In this study， using MC-LR-OVA as the coating antigen， the anti-MC-LR nanobody M110 was selected by four rounds solid phase biopanning. M110 could recognize MC-LR with good stability. Further， an indirect competiitive enzyme-linked immunosorbent assay (ic-ELISA) for the detection of MC-LR was established， with the half-maximal inhibitory concentration (IC50) of 3.55 ng/mL. The detection limit was 0.65 ng/mL and the linear range was 1.28-9.88 ng/mL. The correlation coefficient of ic-ELISA and UPLC-MS/MS was 0.998， indicating the M110-based ic-ELISA method has high accuracy and can be used for the actual detection of MC-LR residues in water sample.

Abstract:A method for rapid screening of pesticide residues in herbal tea by gas chromatography coupled with quadrupole time-of-flight mass spectrometry (GC-Q-TOF/MS) was developed. The target compounds in samples were extracted by ethyl acetate， cleaned by GCB and NH2 sorbent and determined by GC-Q-TOF/MS. The detection limits of 20 controlled pesticides were within 2.00-50.0 μg/kg and the limits of quantitation were 5.0-150 μg/kg. The average recovery of the sample ranged from 73.47%-106.3% at three different spiked levels(25， 50， 125 μg/kg)， with RSDs (n=6) of 0.91%-9.11%. Moreover， the acquired data was compared with the library using the accurate mass of characteristic ion， ratio of product ion and isotopic distribution of characteristic ion to screen pesticide residues in herbal tea. Screening and confirmation was achieved by library search， and the minimum concentration with a score(≥80) was used as the screening limit of the method without reference standards. This method is high efficiency， sensitive and accuracy， and can meet the requirement for non-target rapid screening of pesticide residues in herbal tea.

Abstract:In this work， the detection method of cyanamide in fruits and vegetables was established， using a synthesized rhodamine B-N-hydroxy succinimide (RBS) as the new pre-column derivatizing reagent. After extracted with ethyl acetate and derivatized with RBS， the samples were determined by high performance liquid chromatography-mass spectrometry. The results showed that the reagent RBS had advantages of detection sensitivity for mass spectrometry and was highly efficient and specific in the derivatization reaction of cyanamide. In addition， a better linear relationship was shown when the concentration of cyanamide was 0.005-5 mmol/L， with the correlation coefficient was 0.9969. It was found that the detection limits and quantification limits of this method were 0.001 mmol/L and 0.0025 mmol/L， respectively. The standard recovery rate of samples was in the range of 77.56% - 105.21% and the relative standard deviation was among 1.88% - 4.04%. This method meets the requirements of analysis， with good selectivity， high sensitivity and low detectable limit， and is suitable for the determination of cyanamide residues in fruits and vegetables.

Abstract:Cronobacter sakazakii in infant and baby food can lead newborns and infants to infect meningitis， sepsis and necrotizing enterocolitis， and composed serious threat to their health. In this study， 3 molecular subtyping methods including pulse field gel electrophoresis(PFGE)， multilocus sequence typing (MLST) and enterobacterial repetitive intergenic consensus sequence PCR(ERIC-PCR) were used for Cronobacter sakazakii subtyping for its quick and accurate epidemiological investigation and analysis. Cronobacter sakazakii was isolated from infant formula milk powder， rice flour and complementary food. The classification and subtyping efficiency of the 3 methods were evaluated by Simpson's diversity index (DI) value. The results indicated that PFGE， MLST and ERIC-PCR classified 37 Cronobacter sakazakii isolates into 35 PFGE genotypes， 23 ST types and 28 different ERIC-PCR subtypes， respectively. DI values of PFGE， MLST and ERIC-PCR were 99.55%， 96.40% and 98.05%， respectively. Three molecular methods had high classification ability for Cronobacter sakazakii subtyping， among which， PFEG showed the highest subtyping ability and efficiency.

Abstract:As a medicinal and food resource， Fructus Mori has many biological activities such as antioxidation， hypoglycemic and hypolipidemic. In recent years， as one of its main chemical components， polysaccharides have attracted much attention for their structure， biological activity and function. In this paper， research results reported at home and abroad in recent years were summarized. The extraction and preparation， purification methods， structural characteristics， biological activity and structure-activity relationships of Fructus Mori polysaccharides were systematically reviewed. Finally， personal suggestions for future research and application of Fructus Mori polysaccharides was also put forward.

Abstract:Delivery systems are usually designed to encapsulate bioactive compounds for improving its stability， bioavailability， and tackling their application obstacles. Natural food proteins are biocompatible， non-toxic and biodegradable materials， which are excellent building blocks for food-grade delivery systems. In this paper， curcumin， a typical functional bioactive compound which exhibited high hydrophobicity， low stability， and poor bioavailability was taken as a representative， the raw materials， fabrication methods， interaction mechanisms and different types of protein-based curcumin delivery systems were reviewed. Finally， the development of protein-based curcumin delivery systems were also prospected.

Abstract:Granaticin， as a member of benzoisochromanequinones(BIQ)， has the bioactivities of antibacterial， antitumor and antibiofilm. Granaticin shows the light blue color under the alkaline condition and has potential application in functional pigment. Due to the continuous exploration of the bioactivities and medicinal value of granaticin and its analogs， many researchers are interested in studying it. This review concluded the basic characteristics， sources， biosynthesis and bioactivities of granaticin and its analogues， and provided support for the study and application of granaticin A and its analogues.

Abstract:As a new food packaging technology， intelligent packaging can sense the change of internal environment and atmosphere of stored food sensitively and make visual response， so as to achieve the purpose of monitoring the quality and freshness of food. In recent years， there have been a lot of reports on intelligent packaging materials for aquatic product preservation， especially more and more researches on the application of polysaccharides based food intelligent packaging in aquatic product preservation. In this paper， firstly， the intelligent packaging system and the intelligent packaging of polysaccharides were summarized. And the differences in the film-forming characteristics of several representative polysaccharides were focused， as well as the properties and color-changing mechanism of indicators in the polysaccharides based intelligent packaging were described emphatically. Secondly， the progress of intelligent packaging based on polysaccharides applied in aquatic were reviewed. Finally， based on the current research progress， summed up the problems about the research and application of intelligent packaging film based on polysaccharide， and for the future studies about enhances the stability of polysaccharide based intelligent packaging film has made a further outlook.

Abstract:Konjac glucomannan(KGM) gel has good biodegradability， biocompatibility， environmental sensitivity， water retention， water absorption， antibacterial and other special properties， so it is widely used in the food industry， medicine and chemical industry， functional materials and other fields. However， conventional KGM gels using a single gelling agent have limitations such as low cohesion， weak mechanical properties and structural integrity， insufficient stability to processing and storing， unacceptable appearance， short shelf life， and obvious dehydration shrinkage. KGM based thermal reversible gel is formed by blending KGM with other polysaccharides. This gel with better stability and higher elasticity is formed through strong cooperative interaction between the molecules. Based on the point of molecular assembly， this paper reviewed the synergistic effect between KGM and other polysaccharide (carrageenan， agar， cellulose derivatives， gellan gum， locust bean gum and xanthan) and the mechanism of the thermal reversible gel formation， aimed at improving the strength of KGM based thermal reversible gels and their stability. This work may provide some reference to extend its application range.

Abstract:Long-term， high-intensity exercise can cause exercise-induced immunosuppression in athletes， and increase the risk of upper respiratory tract infection and gastrointestinal infection. As a safe nutritional supplement， probiotics are increasingly used in sports. Increasing evidence suggests that probiotics supplementation can improve the immune function of the body and strengthen the intestinal mucosal barrier function， thereby reducing the incidence， severity， and/or duration of upper respiratory tract infections and gastrointestinal diseases in athletes. These benefits can indirectly promote recovery and improve exercise performance. This article summarized the causes for exercise-induced immunosuppression in athletes， the specificity of probiotic strain/dose and potential mechanisms of action for application in sport， as well as the existing problems， future research directions for probiotics have prospected.