Abstract:The development of novel and effective probiotic encapsulation systems is imperative in light of the susceptibility of probiotics to the acidic and highly-concentrated bile salts environment within the gastrointestinal tract. Carboxymethylated β-glucan (mGN) was utilized in this study to adhere to the surface of Lactococcus lactis (LL) through the bridging of a metal-phenolic network (Fe-TA)， aiming to achieve the single-cell encapsulation of LL (LL@Fe-TA@mGN) and assess the gastrointestinal stress resistance and intestinal retention capacity of LL@Fe-TA@mGN. The results demonstrated that the particle size and zeta-potential of LL@Fe-TA@mGN reached maximum values when 0.12 mg/mL mGN was applied， indicating the full encapsulation of LL at the single-cell level. No significant difference was observed for the growth curve between LL@Fe-TA@mGN and LL in the MRS medium， ruling out the potential toxicity of mGN. Both SEM and TEM clearly revealed the presence of a distinct ‘film’ layer on the surface of LL， providing further evidence that LL was encapsulated within the mGN. With the protection of mGN， the survival rate of LL@Fe-TA@mGN could be up to 14.63 and 1.94 times higher than that of bare LL after exposure to simulated gastric fluid and bile salts for 2 h， respectively. In vivo fluorescence imaging corroborated the prolonged intestinal retention ability of LL@Fe-TA@mGN. In summary， the single-cell encapsulation strategy we developed here could significantly enhance gastrointestinal resistance and prolong the intestinal retention of LL. These results offer novel insights for the development and application of probiotic encapsulation systems.

Abstract:This study took Limosilactobacillus reuteri F22A089 as an example to explore domestication strategies to enhance its nucleoside degradation ability， which provided theoretical basis for obtaining strains with high uric acid lowering ability and targeted domestication of specific functions of probiotics. Two methods of in vitro and in vivo domestication were used to domesticate the ability of probiotics to degrade nucleosides. The results showed that the in vitro domestication method could not rapidly improve the nucleoside degradation ability of probiotics strains， and the nucleoside degradation ability of probiotics strains remained unchanged after 3 weeks of domestication. The study on in vivo domestication of probiotic strains by high-uric acid intestinal environment in mice driven by diet found that the domestication of Limosilactobacillus reuteri F22A089 increased the degradation ability of nucleoside， and the degradation rate of guanosine in some strains reached twice that of the original strain， indicating that it is feasible to target domestication of probiotic strains by host intestinal selection pressure. Whole genome and transcriptome sequencing and mutation site analysis were performed in domesticated strains. Three mutant genes (pbuG_1， rihB and yusV) related to uric acid lowering ability were noted. The mutations of these functional genes were closely related to the enhancement of uric acid lowering ability in domesticated strains. This study was the first to domesticate strains in vivo and improve their ability to degrade uric acid， providing a feasible domestication method for domesticating probiotics through the host gut and enhancing their probiotic efficacy.

Abstract:UPLC-Q-TOF-MS/MS was used to analyze the metabolite profiles of JFP-Ps (Polysaccharides from Artocarpus heterophyllus Lam. pulp) in the serum of DSS colitis rats. Then metabonomics analysis was used to explore the serum metabolite profiles and metabolic pathway. The results showed that JFP-Ps mainly regulated these metabolites such as amino acids， peptides and their analogues， purines and pyrimidines and their derivatives， lipids and lipid-like molecules. There are 5 metabolic pathways related to enteritis in rat serum， namely arginine biosynthesis， D-arginine and D-ornithine metabolism， phenylalanine， tyrosine and tryptophan biosynthesis， phenylalanine metabolism， arginine and proline metabolism. The results indicate that JFP-Ps can attenuate inflammation by regulating amino acid metabolism and influencing related pathways in rats with DSS-induced colitis.

Abstract:Objective: Lycium barbarum， Hippophae rhamnoides L. and calcium fruit are unique food and medicine food in the north of China， in order to develop the nutrients of three kinds of fruits at a deep level， calcium fruit pulp (purity 100%)， sea buckthorn pulp (purity 100%)， wolfberry pulp (purity 100%) three kinds of raw materials in accordance with the volume ratio of 2∶1.5∶1 mixing and blending to make a sweet and sour calcium fruit composite fruit syrup， to explore its functional composition and weight loss. Methods: Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the trace elements of the composite fruit pulp， high-phase liquid chromatography (HPLC) was used to determine the vitamins and carotenoids， and liquid chromatography-mass spectrometry (LC-MS) was used to determine the polyphenolic compounds and organic acid compounds. An obese mouse model was established to investigate the weight loss effect of the composite fruit pulp on obese mice. The results showed that the composite fruit pulp was rich in a variety of functional components， including (73.671±4.918) μg/L of calcium， (503.333±2.054) ng/mg of vitamin B2， and (8.345±0.091) μg/mL of rutin. Compared with the model group， the dose group showed a significant decrease in the body mass of the mice and a significant decrease in the triglyceride content after the intervention of the composite fruit pulp. content was significantly reduced (P＜0.05). Conclusion: Compound fruit pulp has a significant improvement effect on obese mice， and this study provides data support for the nutritional and health care effects of calcium fruit compound fruit pulp， and provides a new nutritional intervention method for obesity prevention.

Abstract:Objective: To investigate the protective effect of Ganoderma atrum polysaccharide (PSG-1) against lipopolysaccharide (LPS)-induced damage in intestinal epithelial cell (IEC-6) and its underlying mechanisms. Methods: The intervention effects of PSG-1 on IEC-6 cells were investigated using a LPS-induced intestinal epithelial cell IEC-6 injury model， and the effect of PSG-1 intervention on cell viability was assessed using the cell counting kit-8 (CCK-8) assay. Western blot technology was employed to investigate the alterations in the expression of intestinal tight junction proteins and cyclooxygenase-2 (cox-2) in the cells. Transcriptome sequencing analysis was conducted to explore the potential protective mechanisms of PSG-1， followed by experimental validation. Results: Intervention with PSG-1 significantly enhanced cell viability and the expression of intestinal barrier proteins， including ZO-1， Claudin-1， and Occludin. Moreover， PSG-1 exhibited an inhibitory effect on the abnormal upregulation ofcox-2 induced by LPS. Transcriptome sequencing analysis， scratch assay， and western blot experiments validation demonstrated that PSG-1 significantly enhanced cell migration ability while suppressing the expression of pro-apoptotic proteins， including Bax， Caspase-3， and Caspase-9. Conclusion: PSG-1 exhibited significant improvement in LPS-induced damage in IEC-6 cell. Cell migration and apoptosis might be key mechanisms through which PSG-1 exerted its protective effects.

Abstract:Objective: This study investigated the phenolic composition and in vitro gastrointestinal digestion and fermentation characteristics of buckwheat hulls (BH) fermented by Lactobacillus plantarum HH-LP56. Methods: The temporal changes in pH value， total phenolic content， and antioxidant activity during L. plantarum fermentation of BH were analyzed， and several representative fermented samples were selected to evaluate the phenolic compositions by HPLC. The bioaccessibility of BH phenolics were evaluated using in vitro gastrointestinal digestion model named Infogest 2.0， and the pH， gas and SCFA production were analyzed to characterize the fermentation properties of BH. Results: The fermented BH at 6 h (LP-6h) significantly increased the total phenolic content， which further increased in the fermented BH at 24 h (LP-24h). The total phenolic content reached the highest level (7.32 mg/g) at 48 hours of fermentation (LP-48h). Analysis of the composition and forms of individual phenolics in unfermented (Raw) and fermented BH revealed that the content of free gallic acid (ranging between 142.88 and 145.87 mg/kg) and protocatechuic acid (ranging between 103.30 and 113.61 mg/kg) in LP-6h， LP-24h， and LP-48h was significantly higher than that in the Raw group (P < 0.01)， as a result， the intestinal bioavailability of gallic acid and protocatechuic acid was significantly increased. Through the inoculation of 5 volunteers' fecal microbiota to simulate colonic fermentation， the results suggested that the gas production， three main SCFA and BCFA contents of Raw and fermented BH were similar. However， within three volunteers， the total SCFA content of LP-6h， LP-24h， and LP-48h was significantly higher than that of Raw BH after 48 hours fermentation (P < 0.01 or P < 0.05). Conclusion: L. plantarum fermentation can effectively improve the gastrointestinal digestion and fermentation characteristics of BH， providing a theoretical basis for the applications in the deep and value-added processing of BH.

Abstract:The effects of different content of small molecular sugars (sucrose， fructose and glucose) on the properties of tamarind seed polysaccharide (TSP) composite gel were investigated. The rheology properties， water holding capacity and texture of small molecular sugar-TSP gel were studied. The moisture distributions of the composite gels were analyzed by low-field nuclear magnetic resonance (LF NMR). The results showed that sucrose and fructose at 45%-60% (m/m) and glucose at 40%-55%(m/m) could make TSP solution (1%， m/V) form gel. When the contents of sucrose and fructose at 55% (m/m) and glucose at 50%(m/m)， the G′， water holding capacity， hardness， cohesiveness and chewiness of sucrose-TSP gel were of 108.39 Pa， 98.20%， 65.55 g， 0.87， 52.55 g， while the G′， water holding capacity， hardness and chewiness of fructose-TSP gel were of 147.36 Pa， 98.57%， 62.29 g， 44.84 g， and the G′， water holding capacity， hardness， cohesiveness of glucose-TSP gel were of 117.46 Pa， 98.56%， 61.86 g， 48.05 g， all of which reached the maximum. At this state， the gels were the most stable and chewable. The results of LF NMR showed that when sucrose and fructose at 55% (m/m) and glucose at 50% (m/m)， the semi-bound water content of small molecular sugar-TSP gels was 99.8%-100%. This might be due to the large amount of hydrogen bonds between hydroxy groups of small molecular sugars and water molecules， and the cross-linking between TSP chains increased， which made the gel much stronger. This study can provide theoretical basis for the application of tamarind polysaccharide in food industry.

Abstract:Hydroxy-α-sanshool (α-SOH)， an amide in peppercorns， interacts with proteins to enhance the numbness of meat dishes in Sichuan cuisine. In order to clarify the structural changes and attachment of the two in meat processing， this experiment explored the mechanism of heat-induced (60， 70， 90 ℃) interactions between pork myofibrillar proteins (MPs) and α-SOH， and resolved the mechanism of numbness activation of α-SOH by molecular docking. The results showed that α-SOH increases the surface hydrophobicity of α-SOH/MPs complexes and promotes the depolymerization of heat-treated MPs. Moreover， the N-H bond in the amide group of α-SOH readily formed stabilizing hydrogen bonds between amino acid residues and altered the subunit aggregation state of the protein， thereby significantly attenuating the bands larger than 45 ku on SDS-PAGE. Fluorescence mapping and circular dichroism results confirmed that α-SOH leads to the transition of protein secondary structure from a regular to a disordered state. Moderately heat-treated (60 ℃ and 70 ℃) MPs were more likely to form complexes with α-SOH， thus reducing the free α-SOH content. The molecular docking results showed that α-SOH activation of hemp flavor was produced by binding to L681 on the TRPV1 receptor. This experiment elucidates the mechanism of interaction between MPs and α-SOH as well as the mechanism of activation of numbness， which can provide a theoretical basis for the regulation of numbness in the processing of meat products.

Abstract:Fish oil is rich in ω-3 polyunsaturated fatty acids with high nutritional value， but it is easy to be oxidized， which is not conducive to the production and processing of products. With the characteristics of good oxidation stability， oil retention and low fat， oleogel not only meets the needs of reducing animal fat， but also improves product quality and nutritional value. It is a fat substitute with high nutrition and low calorie. In this study， beeswax was used as a gelling agent， and sardine oil was used as a base oil to prepare an oil gel. The effects of beeswax addition on the appearance， oil retention rate， texture characteristics， rheological properties and microstructure of sardine fish oil gel were analyzed. The results showed that the beeswax-based fish oil gel was β' crystal form. The addition of beeswax promoted the formation of crystal structure， and also improved the oil retention rate， hardness and gel strength of beeswax-based fish oil gel， when the amount of beeswax added is 8% or more， the oil retention rate reaches 99%. G' does not change with the change of frequency. It can be seen that beeswax-based fish oil gel is a strong gel. Static rheological images show that beeswax-based fish oil gel has shear thinning phenomenon. When the amount of beeswax added was 6%-10%， the texture characteristics and rheological behavior of beeswax-based fish oil gel were similar to those of lard， which provided theoretical support for the replacement of lard by fish oil gel.

Abstract:Alternaria toxins are widespread food contaminants， accompanying with alternariol(AOH)， alternariol monomethyl ether (AME)， tenuazonic acid (TeA)， and Tentoxin (TEN). Currently， there is limited assessment on their combined toxicity. Objective: To evaluate the combined toxicity of four common alternaria toxins on liver cells using BRL-3A cells as a research model. Methods: A CCK-8 kit was applied to detect changes in cell viability of BRL-3A cells treated with 10-200 μmol/L alternaria toxin alone or in combination for 24， 48， 72 h. Based on the combination index method， the combined toxicity after their mixed exposure were analyzed. Results: When the BRL-3A cells were treated with AOH， AME， TeA and TEN alone， the cell survival rate was reduced in a dose- and time-dependent manner. Their IC50 were 38.11， 41.25， 49.05， 358.58 μmol/L(48 h)， respectively. Moreover， the toxicity of AOH-AME， AME-TEN and TeA-TEN combinations all showed additive or synergistic effects at IC10-IC90 levels. The toxicity of the AOH-AME-TeA， AME-TeA-TEN and AOH-AME-TeA-TEN combination showed antagonistic effects at low doses and synergistic effects at high doses， while the other combinations showed the opposite results. Conclusion: All four alternaria toxins in food inhibit the proliferation of BRL-3A cells in varying degrees， with toxicity intensity being AOH > AME > TeA >> TEN. When coexist， a synergistic effect occurs in their toxicity effect， suggests that we need to focus on the combined toxicity risk of toxins in order to assess their safety risk more accurately in the future.

Abstract:Objective: To investigate the inhibitory effects of lactate and osmotic stress on Lactobacillus casei Zhang and to find solutions. Methods: The organic salt stress and osmotic pressure stress were created by using sodium lactate， ammonium lactate and sodium chloride， respectively， to determine the concentration of complete inhibition and plot the osmotic resistance curve， and the physiological damage to LCZ and the protective effect of compatible solutes were observed by measuring the density of the bacteria， the number of viable bacteria and cell damage. The key factors of osmotic pressure elevation were explored by batch culture and constant pH batch culture， and the effect of osmotic pressure reduction was achieved by diluting the fermentation broth， and the changes of bacterial density， viable bacterial count and dry weight yield of the samples were measured after dilution. Results: L-proline has a significant protective effect on LCZ biomass accumulation and cell activity under hypertonic environment， and the optimal addition amount is 2 g/L. The diluted fermentation broth treatment has a significant effect on the density and viable count of bacteria in constant pH supplemented culture. The final fermentation broth OD600nm and viable bacteria count could reach 19.68±0.429 and (3.439±0.110)×1010 CFU/mL， which were 1.61 and 1.46 times of the undiluted treatment， respectively. Conclusion: L-proline can alleviate the activity damage of LCZ under hypertonicity to a certain extent， and reducing the osmotic pressure at the later stage of fermentation by diluting the fermentation broth treatment can greatly improve the fermentation level and cell activity， which can provide reference for industrial production and application.

Abstract:Objective: The aim of this study was to explore the digestive and fermentation properties of four economic red algae， including Gracilaria lemaneiformis， Bangia fusco-purpurea， Eucheuma muricatum and Porphyra haitanensis. Additionally， the anti-inflammatory potential of their fermentation products was evaluated， so as to provide evidences for the high value-added development of red algae. Methods: The changes of total carbohydrates， reducing sugars， proteins and total phenols in four red algae were determined by simulating oral and gastrointestinal digestion and colonic fermentation in vitro. The effects of red algae on intestinal microbiota were analyzed by Illumina MiSeq sequencing of 16S rRNA gene. The content of short-chain fatty acids in fermentation products was analyzed by high performance liquid chromatography. The anti-inflammatory activity of different fermentation products was evaluated by LPS-induced RAW264.7 cell model. Results: During in vitro simulated digestion， Porphyra haitanensis exhibited better bioavailability of carbohydrates， proteins and phenolics. The indigestible portion of these red algae reached the colon and were fermented by the intestinal microbiota. Porphyra haitanensis produced more short-chain fatty acids during fermentation， while all four red algae showed the ability to regulate the intestinal flora， increase the abundance of Bacteroidetes and decrease the ratio of Firmicutes/Bacteroidetes. All fermentation products exhibited significant inhibitory effect on LPS-induced inflammatory injury in RAW264.7 cells， and the Bangia fusco-purpurea fermentation product had a better inhibitory effect than others. Conclusion: Four red algae exhibited good bioaccessibility after in vitro simulated digestion. They were able to modulate the intestinal microbiota composition and showed potential anti-inflammatory activity. These results provided a basis for the development of high-value active products based on red algae.

Abstract:Phytosterols (PS) are water-insoluble and oil-insoluble， and the construction of oil-in-water (O/W)-type nanoemulsions is a common method to enhance their bioavailability and organoleptic qualities， while the stabilizing mechanism of O/W-type nanoemulsions by its own emulsification has not yet been received attention. In this study， phytosterol nanoemulsion (PSN) loaded with different mass fractions of phytosterols (0.1%， 0.5% and 0.9%) was firstly constructed， and the effects of PS concentration on oil-water interfacial tension， as well as microstructure， particle size， ζ-potential， storage stability， oxidative stability， and digestive properties of the emulsion were systematically investigated. The results showed that PS could reduce the oil-water interfacial tension and could form some crystals at the interface， which affected the physical and chemical stability of PSN； the particle sizes of the produced PSN ranged from 165.3 nm to 247.2 nm， and the ζ-potentials ranged from -24.3 mV to -28.4 mV， which increased gradually with the increase of the PS concentration； the emulsions could maintain a good stability after being stored at 4 ℃ for 28 days at 0.1% and 0.5% PSN. However， the storage stability， oxidative stability and digestive properties of the emulsions were not affected by the concentration of PS. However， 0.9% PSN showed optimal kinetic stability under 60 ℃ storage conditions. In addition， the results of the accelerated oxidation test and digestion test showed that higher concentrations of PS could effectively inhibit lipid oxidation and the release of free fatty acids in emulsions (<31.41%). The results of this study may provide theoretical support for the precise development of PS functional foods or excipients.

Abstract:In this paper， the physicochemical properties and digestibility of waxy rice starch(WRS) and oat-β-glucan (OBG) complexes prepared at different freezing ball milling times were investigated， and the physical and chemical properties and digestibility of the complexes prepared at different processing times were characterized and evaluated by scanning electron microscopy， infrared spectroscopy， rheometry and simulated in vitro digestion. The results showed that with the increase of the freezing ball milling time， the surface of the complex particles became rougher and the shape of the particles became more irregular， with agglomeration and agglomeration. The infrared spectral results showed no significant changes in the individual absorption peaks and no new chemical bonds were formed. The freezing ball milling treatment caused the OBG to mosaic or attach to waxy rice starch through hydrogen bonding， and the relative crystallinity of the complex decreased from 29.72% to 8.62%， and the short-range orderliness also decreased gradually. At the same time， the content of the double helical structure of the complex decreased and the content of the amorphous region increased significantly. The peak viscosity and regeneration values decreased from 931.00， 103.33 cP to 159.33， 41.00 cP， respectively， with the increase of freezing ball milling time， and the values of consistency coefficients K， G′ and G″ decreased， enhancing the fluidity and stability of the system. In terms of digestibility， the complexes prepared by freezing ball milling were less digestible than the native waxy rice starch. When the ball milling time was 60 min， the maximum resistant starch content of their complexes reached 35.92%. This study provides new research methods and technical tools for starch processing and modification.

Abstract:The volatile compounds formation mechanism from the self-degradation of several amino acids was studied in subcritical water (SCW). The effect of pH on the self-degradation of several amino acids to generate volatile substances was discussed. The results showed that glycine (Gly)， L-alanine(Ala)， L-arginine (Arg) and L-aspartic acid (Asp) could not be degraded in SCW， which might be due to their simple structure and excellent thermal stability. In SCW system， L-serine (Ser) and L-threonine (Thr) could be decarboxylated to generate the intermediate structure of aminoacetaldehyde， then various pyrazine compounds were generated， which included 2，3，5-trimethyl pyrazine， 3，5-dimethyl-2-(3-methylbutyl) pyrazine， and 3，6-dimethyl-2-ethyl pyrazine. Benzaldehyde， phenylacetaldehyde， acetophenone， and 7-ethyl-1，3，5-cycloheptatriene were the major self-degradation products of L-phenylalanine (Phe). The key intermediate mercaptoacetaldehyde was formed from the self-degradation of L-cysteine (Cys)， and thiophenes， thiazoles， and polysulfides were formed by the reaction of mercaptoacetaldehyde with various aldehydes. According to the formation of volatile substances in each system， the possible volatile substances formation mechanism from various amino acids were proposed in SCW.

Abstract:Jiangshui is a traditional fermented vegetable food in Northwest China. In this study，Jiangshui was used as fermentation substrate to explore the changes of organic acids in Jiangshui during fermentation and their effects on bacteriostasis and antioxidation in vitro. The results showed that in the process of Jiangshui fermentation，the acidity increased gradually，the pH value decreased gradually， and tended to be stable after 4 days， when the Jiangshui fermentation was initially mature. In the determination of organic acid，the content of lactic acid was the highest， the content of lactic acid (3.331 mg/mL)， malic acid and tartaric acid first decreased and then increased， acetic acid increased at first and then decreased，and the content of citric acid increased as a whole. The bacteriostatic zone of Jiangshui against Escherichia coli and Staphylococcus aureus first increased and then decreased as the fermentation proceeds，and the maximum value was reached at the 7th day， of 12.5 mm and 11.4 mm， respectively. The mass concentration of total flavonoids in Jiangshui was 3.64 mg/L on the 5th day and 52.44 mg/L on the 6th day. DPPH radical scavenging rate， ABTS radical scavenging rate， ferrous ion concentration and reducing power four kinds of antioxidant models were used to analyze the antioxidant activity of Jiangshui during fermentation. It was found that the antioxidant capacity of Jiangshui increased gradually during fermentation. In this study， various indexes in the process of Jiangshui fermentation were measured and analyzed， so as to provide reference and reference for the quality analysis of Jiangshui， standardization and industrialization of Jiangshui fermentation process.

Abstract:Beef is rich in protein and low in fat， which is liked by consumers. It is difficult to chew and has low added value. In order to improve the taste and flavor of beef， the effects of single or combination patented strains， including W9-3 Lactobacillus reuteri， M3-16 Lactobacillus paracasei and MY4 Kluyveromyces marxianus， on the physicochemicals and sensory qualities， biogenic amine formations and volatile flavor of beef were investigated. The results showed that the addition of starter cultures could significantly decreased the pH (below 5.5)， the water activities (decreased by 0.6%-4.1%)， TBA values and carbonyl values of beef compared with unfermented or naturally fermented beef. The addition of starter cultures could inhibit the formations of histamine， tryptamine， tyramine and butylenediamine， and at the same times， make the brightness and springiness of cooked beef increase， while the hardness， gumminess， chewiness and cohesiveness decrease. And the results of the combination groups were higher than single strain groups. Eighty-six volatile substances have been identified from roasted fermented beef by using SPME-GC-MS. The results of these flavor compounds relative contents and PCA analysis showed that the flavor of roasted beef after fermentation with starter cultures are different from that of unfermented and naturally fermented beef， with the formation of new alcohols， aldehydes and ketones. The sensory evaluations showed that the texture， color， odor and taste of beef could be improved by fermentation with starter culture. The starter， especially the compound starter， can improve the quality and the flavor， while inhibit the biogenic amine formation of fermented beef. This paper could offer the theoretical foundation to the beef fermentation technology optimation.

Abstract:Malolactic fermentation is one of the most important processes which influence biological stability and flavor quality of red wine. Recently， the selection and application of indigenous lactic acid bacteria gained more and more attention by researchers and wine makers. In this study， a selected Pediococcus parvulus C30 from Gansu Hexi Corridor was used， effects of malolactic fermentation on fermentation kinetics， chemical composition and sensory properties of Pinot Noir wine， Merlot wine and Cabernet Sauvignon wine were analyzed. The results showed that both the Pediococcus parvulus C30 and commercial lactic acid bacteria could complete malolactic fermentation in 12-36 days. Physical-chemical index， including reducing sugar， alcohol content， total acidity and volatile acidity of fermented wine meet the national standard in China. Compared with control wine， Pinot Noir and Cabernet Sauvignon wines fermented by C30 strain showed significantly higher in volatile esters and alcohols， which might contribute stronger fruity and floral notes in wine. Sensory evaluation indicated Cabernet Sauvignon wine elaborated by C30 strain showed the most intense and elegant aroma， with well-balanced wine body. This study provided a possible use of selected lactic acid bacteria as starter cultures in domestic dry red wine production.

Abstract:In this study， antifreeze crude peptide was obtained from crucian carp fish scales by trypsin enzyme digestion. And the formulation was designed by using {3， 3} simplex lattice method with antifreeze crude peptide， trehalose and alginate oligosaccharides as factors. The survival rate of Streptococcus pyogenes (S. pyogenes) after 24 h of freezing was used as the screening index for antifreeze activity to obtain the theoretical model formulation of the compound antifreeze. The optimum group of composite antifreeze (K1， K2) and the theoretical model formulation group (K3) were further selected for the frozen channel catfish(Ictalurus punctatus) myofibrillar protein test to verify the antifreeze effect of the composite antifreeze. The results showed that the survival rate of S. pyogenes in the antifreeze crude peptide group reached only 57.11%. The infrared spectra of the interaction with soy lecithin showed that the crude antifreeze peptide might interact with the hydrophilic head of phospholipids and water， which could help to stabilize the membrane structure. The survival rate of S. pyogenes reached more than 80% in the K1 and K2 groups， and as high as 92% in the K3 group. The hydrophobicity of the protein surface was significantly reduced (P< 0.05) and the protein solubility was significantly increased (P< 0.05) by the addition of K1， K2 and K3 complex antifreeze. The α-helix and β-fold content of K1 and K2 were significantly decreased (P< 0.05)； and the r-values of K2 and K3 were significantly decreased (P< 0.05). In summary， the theoretical model K3 is a good aquatic products composite antifreeze with high antifreeze activity， which can inhibit protein aggregation and maintain the stability of protein structure. This study provides a new idea for the efficient development of composite antifreeze， and provides a theoretical basis for the subsequent development of catfish pre-prepared vegetables frozen products.

Abstract:The objective of this study was to develop a heat transfer model for gas grilling of salmon steaks and evaluate the inactivation behavior of Listeria monocytogenes under different grilling conditions by incorporating microbial thermal inactivation kinetics. The one-dimensional unsteady heat transfer model was used to describe the heat transfer process during gas grilling of salmon， and the model parameters were solved by the combination of the finite difference method and least square optimization algorithm， then the temperature history during gas grilling was also obtained. Finally， the lethality of Listeria monocytogenes during gas grilling was calculated by the General Method. The results showed that the thermal diffusion coefficient， convective heat transfer coefficient of flame side and air side were 1.83 × 10-7 m/s2， 15.18 W/(m2·℃) and 16.36 W/(m2·℃)， respectively. Verification tests showed that the developed model can be suitable for describing the heat transfer during gas grilling of salmon， with the RMSE of 1.48-3.33 ℃ between the model predictions and the measured values. In addition， numerical simulation of different scenario showed that Listeria monocytogenes could still survive in salmon steaks if they were unevenly turned during the roasting process， even if the center temperature up to 71 ℃， however， if they were flipped evenly with the time interval of 2， 3， 4 min or 5 min during gas grilling， the lethality of Listeria monocytogenes at all locations was greater than 5.21 lg(CFU/g) when the center temperature of the salmon steak reached 71 ℃. The results of this study can provide scientific guidance for safe cooking.

Abstract:Objective: To improve the stability and bioavailability of xanthine oxidase (XOD) inhibitors， microcapsules based on XOD inhibitors were prepared by spray drying method. Methods: Using the grafting degree as an index， the preparation process of the glycosylation reaction product was optimized by single factor， and the structure was characterized by Fourier transform infrared spectroscopy， ultraviolet spectroscopy， fluorescence spectroscopy， etc.， to explore the effect of different reaction times on the functional properties. The microcapsules were characterized by SEM， XRD and differential scanning calorimetry， using the glycosylation reaction product of soybean protein isolate (SPI) and pullulan as the wall material. The release rate and storage stability of microcapsules in simulated digestive juice were studied. Results: The optimal preparation process of glycosylation products was that the protein content was 1.5%， the mass ratio of protein and sugar was 1∶2， the reaction time was 20 min， and the grafting degree was up to more than 35%. The characterization results showed that the glycosylation modification of SPI was successful， and the solubility was increased by 40%， the emulsifying activity and emulsifying stability were increased by 2 times and 4 times， respectively， and the surface hydrophobicity index was reduced by 225， which was beneficial to be used as a microcapsule wall material. After embedding p-hydroxycinnamic acid (HCA) and hesperetin (HES)， SEM， observed microcapsules with uniform size and smooth surface， XRD diffraction spectrum and differential scanning calorimetry verified the successful embedding of HCA and HES. Microcapsules increased the bioavailability of inhibitors by 50%， and the storage stability of microcapsules was good. Conclusion: This experiment successfully developed the XOD inhibitor microcapsule formulation based on lactic acid bacteria metabolites. The high-efficiency embedded XOD inhibitor microcapsules provide the basis for the development and utilization of HCA and HES as biologically active substances in functional foods.

Abstract:Objective: Isolate and purify polysaccharides from Artemisia integrifolia and to investigate their antioxidant activity. Methods: The optimum extraction process was obtained by ultrasonic-assisted enzymatic extraction of polysaccharides from Artemisia integrifolia using response surface methodology. Results: The optimum extraction process was obtained as follows: ultrasonic power 300 W， material-liquid ratio 1∶30 g/mL， ultrasonic time 46 min， addition amount of cellulase 2.0%， addition amount of pectinase 3.0%， and under this condition， polysaccharide yield 7.67%. A total of six polysaccharide fractions were obtained by separation and purification using DEAE-52 chromatography column. Antioxidant activity studies on both AIP-2 and AIP-3 fractions showed that both AIP-2 and AIP-3 treatments at different mass concentrations had strong concentration-dependent protective effects against H2O₂-induced oxidative damage in HepG2 cells. Compared with the model group， treatment with high mass concentrations of AIP-2 and AIP-3 (50 μg/mL) increased cell survival by 54.35% and 60.26%， SOD viability increased by 35.86% and 38.98%， CAT viability increased by 173.02% and 205.42%， GSH-PX viability increased by 50.24% and 50.78%， and MDA content decreased by 46.13% and 53.87%. Conclusion: Artemisia integrifolia polysaccharide has good antioxidant activity.

Abstract:After extraction， dialysis and gel filtration chromatography， the myrosinase in fresh maca tubers was purified. The enzymatic properties， kinetic parameters of myrosinase were studied. Moreover， the effect of drying on the myrosinase activity and benzyl isothiocyanate (BITC) content of maca was investigated. The molecular weight of purified myrosinase was 190.9 ku determined by gel permeation chromatography (GPC). The results of enzymatic properties showed that the optimum temperature of myrosinase was 40 ℃， and the optimum pH value was 7.0. The metal ions Fe3+， Cu2+， Al3+， Mg2+， Zn2+， Ba2+ had significant inhibitory effects on the myrosinase. The kinetic parameters Vmax = 0.2383 (μmol/L)/min， and Km = 0.1425 mmol/L were determined by the method of Lineweaver-Burk. The myrosinase activity and BITC content of fresh maca were 0.7256 U/g and 3.3190 mg/g， respectively. The fresh maca samples were sliced and dried at the temperature of 50， 60， 70 ℃， and 80 ℃， respectively. As the drying temperature increased， the myrosinase activity in the maca sample significantly decreased， and the BITC content showed a decreasing trend. This study has improved the theoretical study of the myrosinase from maca. It is proposed that drying maca at temperatures above 60 ℃ can effectively inhibit the myrosinase activity. These results may provide guidance for the processing and utilization of maca.

Abstract:The content of ions in tea water are the key factors affecting the flavor quality of green tea infusion. In order to develop special water for infusing tea and corresponding equipment， different kinds of ores (quartzite， medical stone， strontium-rich filter material， weak alkali filter material and high TDS filter material) were used as the research objects to explore the effect of ore soaking water on the flavor quality of green tea infusion. The ore soaking water research results showed that there were significantly different in the effects of ore-water ratio， soaking time and soaking temperature on the leaching law. The content of ions in the soaking water of High TDS (total dissolved solids) filter material was the highest， and the dissolution stability of quartzite was the best. The optimal treatment of ore soaking water was that the ore to water 1∶50(m/V) at room temperature and soaking 5 min. The ore soaking water quality study showed that the conductivity of ores increased after soaking in water and boiling but changed less than 10 μs/cm， while there was a significant difference between the pH values (P<0.05). It was found that the conductivity thermal stability of ores soaking water was better than pH thermal stability. With the increase of conductivity of ores soaking water， the astringency of green tea infusion was clearly enhanced and there was a significant correlation between Ca2+ content and astringency intensity of tea infusion (P<0.01)， among the detected cations (K+， Na+， Mg2+， Al3+， Ca2+). The active addition test showed that Ca2+ could significantly enhance the astringency of green tea infusion and catechin solution. In summary， Ca2+ is the most key ion that affects the astringency of green tea infusion in ore soaking water. It would effectively regulate the overall flavor quality of green tea infusion by adjusting the content of Ca2+ in brewing water.

Abstract:The scenting of traditional scented tea is mainly based on the combination of flowers and tea. In order to explore the effects of different scenting methods on the taste and quality chemical composition of rose black tea. The scenting of rose black tea was completed by four scenting methods (flower scenting， rose cell sap spraying scenting， rose cell sap steam scenting， petals and cell sap steam combined scenting). Based on the indexes of color difference， total tea polyphenols， free amino acid content and catechin， the aroma analysis results of rose black tea prepared by different scenting processes were analyzed by HS-SPME-GC-MS. The results showed that there were significant differences in the physical and chemical components of rose black tea obtained by four different aroma methods (P < 0.05). The two kinds of black tea soup with fresh flower fragrance and cell sap spraying fragrance are red and yellow， and the brightness is not as good as the other two scenting methods. The amino acid content of rose black tea obtained by scenting method of spraying rose cell sap was higher (112.66 mg/L). The content of tea polyphenols in rose black tea scented with rose flowers is low (680.38 mg/L). The main aroma compounds of rose black tea were phenylacetaldehyde， linalool， (E，E) -2，4-heptadienal， methyl salicylate， phenethyl acetate， β-ionone， geraniol， 2-pentylfuran and hexanal. The nine main aroma compounds in rose black tea scented by rose fresh flower cell sap were significantly higher than those of the other three.

Abstract:Furan is a class 2B carcinogen that may cause human cancer. It is mainly formed during the thermal processing of food. The oxidation of polyunsaturated fatty acids (PUFAs) is an important way to form furan. However， the research on the formation of furan from PUFAs is still in its infancy. Therefore， linoleic acid was selected as a representative fatty acid in present study. The effects of processing conditions (temperature， time， pH， water contents， metal ions， polyphenol) on the formation of furan of linoleic acid oxidation were preliminarily investigated by headspace injection-gas chromatography-mass spectrometry (HS-GC-MS). The results showed that furan content increased with the increase of heating temperature and time. The addition of water significantly promoted the formation of furan， and with the increase of water content (0-100 μL)， the promoting effect increased first， then decreased and finally become stable. The addition of metal ions such as Cu+， Cu2+ and Fe3+ significantly promoted the formation of furan(P < 0.05)， while the addition of K+， Na+ and Ca2+ has no significant effect on the formation of furan. Compared with neutral conditions， acidic conditions had no significant effect on the formation of furan， while alkaline conditions significantly inhibited the formation of furan (P < 0.05)， with an inhibition rate of 56.64%. In addition， the addition of polyphenols， such as epicatechin gallate (ECG)， myricetin， quinic acid， p-coumaric acid， and chlorogenic acid， significantly inhibited the formation of furan (P < 0.05). Among them， myricetin had the best inhibitory effect， and the inhibition rate was up to 55.54%. The results of this study can provide a theoretical reference for the regulation of furan during lipid thermal processing.

Abstract:Allium mongolicum Regel must be made into powder so as to be used widely in the food industry， and the quality of Allium mongolicum Regel powder determines the application range of Allium mongolicum Regel. In this paper， the methods of vacuum freeze drying (FD)， vacuum drying (VD) and hot air drying (HAD) were used to dry Allium mongolicum Regel， and the dried Allium mongolicum Regel were ground to obtain Allium mongolicum Regel powder， and the quality characteristics of Allium mongolicum Regel powder with different particle sizes were further explored. The results showed that the drying method had significant effects on the yield， rehydration， bulk density， fluidity and color of Allium mongolicum Regel powder (P<0.05). FD powder has the smallest average particle size (30 μm)， the largest bulk density (1.57 g/mL)， the highest brightness (56) and the highest angle of repose (47.77°). The micromorphological distribution of HAD and VD Allium mongolicum Regel powder is uniform， composed of round， oval and other particle shapes， and the particles are more dispersed. The micromorphology of FD Allium mongolicum Regel powder is composed of flakes， chips and other particle shapes， and the particles are more aggregated with higher bulk density. The other characteristics of FD Allium mongolicum Regel powder is highest yield (50%) when bigger particle (50 mesh) is obtained.

Abstract:The stinky mandarin fish was stored at superchilled temperature(-2 ℃)， and the changes of garlic-cloves shaped meat quality， protein composition and volatile flavor compounds of fish were investigated. The results showed that the garlic-cloves shaped meat turned red after storage for 15 days， the a* value increased from negative (green) to positive (red) and the whiteness decreased significantly. The hardness continuously increased whereas springiness and cohesiveness showed a reverse trend， the overall sensory quality also decreased significantly. The SDS-PAGE results revealed that the sarcoplasmic protein and myofibrillar protein continuously degraded during superchilled storage. The results of GC-IMS analysis showed that a total of 31 kinds of volatile flavor compounds were detected during storage. Octanal， propionic acid， acetoin， hexyl acetate and amyl butyrate continuously accumulated during storage. The content of propionic acid with irritating odor was relatively high， and increased significantly after storage for 15 days， which make against the normal flavor of stinky mandarin fish. In summary， the sensory and flavor qualities of stinky mandarin fish maintained well within 15 days under the superchilled storage at -2 ℃ and began to deteriorate afterwards. The results provides a theoretical basis for the quality controlling of stinky mandarin fish during superchilled storage.

Abstract:In this study， antagonistic yeast for controlling black spot of postharvest cherry tomato was to be screened by in vitro and in vivo test， and the biocontrol efficacy of this antagonistic yeast against the natural decay of cherry tomato and its effects on the quality of fruits were then investigated. The direct and indirect inhibition of this yeast on Alternaria alternata was explored through its effects on spore germination， germ tube elongation and hyphae structure of this pathogen， and its growth dynamics on wound and surface of cherry tomato， respectively. Then， the effects of antagonistic yeast on the expression levels of resistance-related genes in cherry tomato were determined by RT-qPCR technology to analyze the effect of antagonistic yeast on the disease resistance of the fruits. Results indicated that Pichia caribbica showed the best control efficacy against postharvest black spot of cherry tomato， and the disease incidence of yeast-treated fruits was only 16.25% which was significantly lower than that of the control (68.76%). This antagonistic yeast could also significantly reduce the natural decay of postharvest cherry tomato and slow down the deterioration of quality. P. caribbica could directly inhibit the growth of A. alternata by inhibiting the spore germination and mycelial elongation as well as parasitic on mycelia of A. alternata. It also could indirectly inhibit the growth of A. alternata by competing with the pathogen for nutrition and space on the wound and surface of cherry tomato. P. caribbica could induce the expression levels of antioxidant genes (SOD， CAT and APX) and pathogenesis-related genes (PR genes) (GLU and CHI) in cherry tomato. P. caribbica showed biocontrol efficacy against postharvest black spot and natural rot of cherry tomato， and had no significant adverse effects on fruit quality. It alleviated postharvest diseases of cherry tomato by inhibiting the growth of pathogen and increasing the expression of resistance-related genes.

Abstract:Odor-induced taste enhancement is considered to be an effective way to enhance the perception of saltiness in low-salt food system. In this study， the key aroma compounds in dry Agaricus bisporus were characterized by solvent-assisted flavor extraction， gas chromatography-mass spectrometry， gas chromatography-olfactometry， aroma extract dilution analysis and odor activity value(OAV) calculation. The odorants associated with saltiness perception were selected using gas chromatography-olfactometry/associated taste (GC-O/AT)， and their potential effects on perceived salty taste were verified by sensory analyses of 2-alternative forced-choice and odor-induced saltiness enhancement value. The results showed that a total of 47 aroma compounds were identified in the mushroom sample， 18 of which were characterized as key aroma compounds with OAV greater than 1. By GC-O/AT， 6 compounds related to saltiness perception were preliminarily screened from the key aroma-active compounds in dry Agaricus bisporus. Sensory experiments suggested that odorants including p-cresol， 2-methyltetrahydrofuran-3-one， 1-pentanol， and 1-octen-3-ol of certain concentrations could enhance the saltiness perception significantly. The research could provide a reference for increasing saltiness perception of low-salt foods by aroma-taste interaction.

Abstract:Real-time and visual monitoring fish freshness is crucial to safeguard food quality and consumer safety. In this study， a fluorescent probe CDI with a donor (D)-π-acceptor (A) structure was synthesized from 4-(dimethylamino) cinnamaldehyde and isophorone malononitrile to monitor the freshness of salmon in real time. The probe responded apparently to 13 amines and its fluorescence detection limit was as low as 9.91 μmol/L for the cadaverine produced during the spoilage process of aquatic products. The indicator label loaded with probe CDI+H+ was obtained by physically depositing probe CDI on fiber filter paper， and then hydrochloric acid was added to protonate it. When the indicator label was placed over salmon meat， the indicator label changed from white to light yellow until yellow， and the fluorescence gradually turned on from purplish pink to orange-red as the freshness of salmon meat decreased. By comparing with the total volatile base nitrogen value， it was verified that the indicator label loaded with probe CDI+H+ could effectively distinguish the three freshness levels of salmon by colorimetric and fluorescent dual response.

Abstract:Mercury ion， a kind of heavy metal contaminant with high toxicity， poses significant health risks to the human body. It is of great significance to control the content of mercury ion in food. Carbon dots (CDs) with high fluorescence were prepared by one-step hydrothermal method， in which citric acid was used as carbon source and different amino acids was used as nitrogen source. The influence of the nitrogen doping of different amino acids on the fluorescence quantum yield (QY) of CDs and the response of these nitrogen doped CDs to mercury ions was explored. The results showed that the carbon chain lengths and functional groups of different amino acids have a certain effect on the QY of CDs. Further， Hg2+ can effectively quench the fluorescence of Gly-CDs doped with glycine as a nitrogen source. Moreover， Gly-CDs has good fluorescence stability. Under the optimal experimental conditions， the linear range of Gly-CDs for the detection of Hg2+ is 0.00-7.00 μmol/L and 8.00-60.00 μmol/L with a detection limit of 0.20 μmol/L. It has been successfully applied to detect Hg2+ in beverage samples. The recovery rate was between 90.08%-107.90%. The method is simple， sensitive， rapid and suitable for accurate determination of Hg2+ in beverages.

Abstract:Aflatoxin B1 (AFB1) is a highly toxic and carcinogenic foodborne contaminant that seriously threatens food safety and public health. To develop a rapid bioluminescent enzyme immunoassay (BLEIA) for detecting AFB1， this study systematically evaluated the soluble expression， purification， and enzymatic activity of three anti-AFB1 nanobody-nano luciferase fusion proteins (G8-Nluc， Nluc-NB26， and Nluc-NB28). Based on the three fusion proteins， BLEIA assays were established， and Nluc-NB26 was selected for the analysis and validation of cereal samples. The results indicated that Nluc-NB26 exhibited the highest soluble expression level and better stability， followed by Nluc-NB28， while G8-Nluc was largely insoluble. Testing with various surfactants revealed that adding sodium lauroyl sarcosinate improved the solubility of G8-Nluc significantly. The purified fusion proteins all exhibited suitable enzymatic and antigen-binding activities. BLEIA results based on the fusion proteins showed the IC50 values for detecting AFB1 were 4.213， 1.697 and 2.169 ng/mL for the Nluc-NB28-BLEIA， G8-Nluc-BLEIA and Nluc-NB26-BLEIA systems， indicating that G8-Nluc-BLEIA had the highest sensitivity， comparable to Nluc-NB26-BLEIA， while Nluc-NB28-BLEIA had the lowest. Considering the soluble expression level， stability， and detection performance of the fusion proteins， Nluc-NB26-BLEIA was further applied to analyze and validate cereal samples. The results demonstrated that this method achieved average recovery rates of 91.1% to 104.1%， comparable to commercial ELISA kits， but with significantly reduced detection time and reagent cost. These findings offer valuable insights for developing rapid and highly sensitive detection techniques for AFB1.

Abstract:Traditional Huangjiu is the treasure of Chinese brewing technology， but its semi-open brewing environment is easily affected by ambient temperature conditions， which leads to the instability of product flavor quality. In this study， traditional Huangjiu brewed under different ambient temperature conditions (pre-wine (S1)， neutral wine (S2 and S3)， post-wine (S4)) was selected as the research object， and the difference of static taste intensity of four batches of traditional Huangjiu was analyzed by quantitative description sensory evaluation. Time-intensity sensory evaluation and dynamic dominant attribute test were used to analyze the dynamic change of taste characteristics and the difference between different batches. The difference of taste profiles was analyzed by electronic tongue technique， and the taste prediction models were established by combining partial least square method. The results showed that the taste of S2 and S3 is harmonious and full， the umami is prominent， and the bitter and delayed bitterness intensity is weak. The dominant taste properties of the four batches of traditional Huangjiu were sour taste， bitter taste and umami taste in order of time. The bitterness dominant attribute of S3 ended the earliest (85 s)， the bitterness disappeared the longest (110 s) in S4， and the umami dominant attribute of S3 was the earliest， followed by S2， S1 and S4. The electronic tongue has a good correlation with sour， bitterness and delayed bitterness sensory attributes， respectively. The prediction model for delayed bitterness was robust with a correlation coefficient of 0.976. Static and dynamic sensory evaluation combined with electronic tongue can comprehensively evaluate the taste characteristics of traditional Huangjiu. The ambient temperature conditions have an important influence on the bitterness and delayed bitterness of traditional Huangjiu.

Abstract:In this study， the matrix effects of exogenous addition of four representative polyphenolic substances on the stabilisation and aroma presentation of fermentation volatiles in Cabernet Sauvignon dry red wines were investigated. Cabernet Sauvignon wine grapes were used as test material for winemaking， and exogenous chlorogenic acid， protocatechuic acid， quercetin and rutin were added singly prior to alcoholic fermentation. The fermentation aroma compositions and aroma profiles of wine samples from the treatment and control groups were analysed and evaluated at the end of alcoholic fermentation. Aroma components were analysed qualitatively and quantitatively by HS-SPME-GC-MS， and aroma profiles were quantitatively assessed by a sensory-trained tasting panel. The results showed that: a total of 27 fermentation aroma components were detected in the wine samples， among which 12 components had an odour activity value (OAV) greater than 1.0； from the contents of total esters， ethyl esters and ethyl esters of short-chain fatty acids， the chlorogenic acid， protocatechuic acid and quercetin treatment groups all showed better stabilising effects； from the contents of acetate esters， the treatment groups all presented better substance contents； from the content of medium chain fatty acid ethyl ester， all treatment groups except protocatechuic acid were significantly lower than the control group. Compared with the control group， all treatment groups showed some enhancement of fruity aroma characteristics， especially the chlorogenic acid treatment group. Further analysis of the OAV of each aroma substance revealed that the chlorogenic acid treatment significantly enhanced the sour fruit， strawberry， and lactic flavours of the wines， while the protocatechuic acid treatment significantly enhanced the banana， strawberry， green apple， and sweet fruit flavours of the wines， compared with the control group. It can be seen that the addition of certain concentration of polyphenols such as chlorogenic acid and protocatechuic acid before alcoholic fermentation can effectively retain the fermentation aroma substances in wine and significantly enhance the fruity character of wine. This study clarified the polyphenol matrix effect of wine aroma， providing reference for the optimization practice of wine aroma enhancemen.

Abstract:Objective: To study the effect of blueberry anthocyanin (blueberry anthocyanin， BA) on the volatile compounds of tilapia fish skin and to reveal the deodorisation mechanism. Methods: Tilapia fish skin was treated with different mass concentrations of blueberry anthocyanin， and the changes of flavour substances were analysed by electronic nose， GC-IMS and GC-MS. Results: Fish skin of 0.03， 0.06， 0.12， 0.24 mg/mL BA group obtained lower response values than blank group and control group (0.06 mg/mL GA) in the electronic nose sensor for characterising flavour substances， and the response values of blank group in the characterisation sensors W2S， W1W， W1S were 1.106， 1.196， and 1.114， respectively， which indicated that BA treatment could effectively reduce the alcohols， aldehydes， ketones， sulphur-containing compounds， aromatic compounds and other substances in the fish skin. The results of GC-IMS identification fingerprints showed that the volatile substances of the BA-treated fish skin differed from those of the blank group. The quantitative results of GC-MS again verified that the contents of the characteristic flavour compounds and the odour activity values in the fish skins were affected by BA， and the content of heptanal was reduced from 159.16 μg/kg to 121.46 μg/kg， the content of octanal from 121.62 μg/kg to 99.90 μg/kg， and the content of nonanal from 445.57 μg/kg to 419.58 μg/kg， etc， and BA treatment caused the volatiles to differ from the blank group (P<0.05)， etc. BA treatment resulted in a significant difference in the content of trans-2-nonenal in the fish skin， which was 17.00 μg/kg in the 0.03 mg/mL BA group(P<0.05)， and the relative importance of the individual volatile compounds on the flavour of the tilapia fish was assessed by the change in the value of odour activity. Conclusion: The present study revealed that BA has an effect on the changes of characteristic flavour components in tilapia fish skin， BA treatment reduced the response values elicited by flavour compounds in the skin on the electronic nose characteristic sensor and caused a reduction in the content of flavour compounds in the skin， which can improve the quality changes of tilapia skin during storage， and revealed the mechanism of BA on the formation process of characteristic flavor.

Abstract:In order to study the characteristics of umami monomers and umami intensity of different kinds of umami solid compound seasonings， 141 commercially umami solid compound seasonings were taken as the research objects. According to industry standards and ingredients， they could be divided into three categories， chicken essence seasonings， chicken powder seasonings， and other seasonings. What's more， other seasonings could be divided into terrestrial animal seasonings， aquatic seasonings， plant seasonings， and synthetic seasonings. The contents of seven umami monomers including free amino acids， 5'-nucleotides and Na+ in umami solid compound seasonings were detected by the instrument， and the umami intensity was quantified by the calculation of equivalent umami concentration (EUC). The results showed that the contents of glutamic acid (Glu) and Na+ in chicken essence were the highest， and the contents of umami monomers of other types were higher than that of chicken essence and chicken powder except for Glu and Na+. Among other seasonings， the Na+ contents of terrestrial animals were higher. The free amino acid contents of aquatic animals were higher. The contents of 5'-nucleotides in plants were higher. The contents of Glu in synthetic seasonings were significantly higher than that of the other seasonings. In terms of umami intensity， other seasonings > chicken essence seasonings > chicken powder seasonings. Among other solid compound seasonings， synthetic seasonings > aquatic animal seasonings > plant seasonings > terrestrial animal seasonings. EUC could be used to objectively quantify the intensity of umami and provide theoretical basis and data support for flavor research， quality evaluation， and consumer purchase of umami solid compound seasonings.

Abstract:In order to explore the flavor characteristics of instant bird's nests with different storage times. Gas chromatography-ion mobility spectroscopy (GC-IMS) was used to analyze the volatile organic compounds of commercial bird's nests at five storage times. The results showed that the volatile components of instant bird's nests varied significantly at different storage times (P < 0.05). A total of 44 volatile organic compounds (including monomers and dimers) were identified， mainly for aldehydes and esters. Principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) could effectively discriminate the instant bird 's nests with five storage time. According to the variable important in the projection (VIP) of PLS-DA model， the results of fingerprint map and hierarchical clustering analysis， 12 (VIP>1) characteristic volatile substances were finally selected. These characteristic flavor components are acetic acid (M， D)， (Z)-hept-4-enal， butan-2-one (M)， 3-methyl-3-buten-1-ol， heptanal， ethyl acetate (D)， propyl acetate (M)， pentanal， butanal and propyl acetate (M， D). The samples of instant bird's nests with different storage times can be better discriminated by these characteristic compounds.

Abstract:Objective: To study the chemical constituents of Polygonum multiflorum leaves and lay a foundation for the research and development of functional food of P. multiflorum. Methods: Organic solvent fractions was performed on the alcohol extract of P. multiflorum leaves to obtain different fractions parts such as petroleum ether， dichloromethane， ethyl acetate， n-butanol， and water. Anti-inflammatory activities were carried out on different extraction parts. The fractions with strong anti-inflammatory activity were separated and purified by using silica gel and C18 column combined with semipreparative HPLC methods. Results: The ethyl acetate fraction had no cytotoxicity on RAW264.7 cells in the concentration range of 0-100 μg/mL and showed dose-dependent inhibition of NO production. Petroleum ether and dichloromethane fractions displayed no cytotoxicity in the concentration range of 0-25 μg/mL， the inhibitory rate on NO of dichloromethane fraction (51.47%) was higher than the fraction of petroleum ether (43.91%). Eleven compounds were isolated from the fractions of ethyl acetate and dichloromethane. The chemical structures were identified as 2，3，4，6-tetrahy-droxyacetophenone-3-O-β-D-glucoside (1)， myricitrin (2)， quercitrin (3)， afzelin (4)， β-sitosterol (5)， n-hexacos-5， 8， 11-trienoic acid (6)， hexacosane (7)， α-linolenic acid (8)， kaempferol-3-O-rutinoside (9)， myristic acid (10) and quercetin (11). Conclusion: P. multiflorum leaves showed good anti-inflammatory activity， and compounds 2， 4， 6， 7， 8， 9， 10， 11 were isolated and obtained from P. multiflorum for the first time.

Abstract:Hierarchical structures are long-range controllable high-level structures that are assembled by confined assembly at the multidimensional spaces of unit structures with short-range orders. Hierarchical structures are characteristic of directional arrangement by unit structures and high programmability in their scales and dimensions. Due to dynamic design logic and normalized construction mechanism， such highly organized and spatially diverse structures assembly with similar unit structures may find critical applications in design of functional foods. However， current design and development of hierarchical structures are based on artificial polymers and engineered proteins， while it is yet to have studies focused on natural proteins. The primary reason is the lack of process control of protein folding. In this paper， the research progress on the precise construction of hierarchical structures of food proteins is reviewed， which is based on protein co-construction technology from three aspects: mesoscopic reconfiguration， nanoscale carving， and hierarchical customization. This work provides new ideas and methods for constructing the key technological system for value-added utilization of food proteins， trying to provide certain theoretical and practical support for promoting the development of food protein industry in China.

Abstract:Photodynamic inactivation is a new pathogenic bacterium killing technology. It activates photosensitizers through light sources to generate reactive oxygen species that target bacterial cell membranes and DNA， causing oxidative damage and ultimately leading to bacterial death. Traditional sterilization methods are faced with many problems in the food industry， such as the emergence of drug-resistant bacteria， biofilm bacteria are difficult to kill， food nutrition and flavor loss， and the high cost to application. As a non-thermal sterilization technology， photodynamic inactivation does not cause sensory changes and nutrient loss of food， requires simple equipment and low energy consumption， does not cause bacterial resistance， and has a good killing effect on bacteria (planktonic bacteria and biofilm)， fungi， and even spores， which has attracted widespread attention in recent years. This article reviewed the limitations of traditional antibacterial methods， the principle of photodynamic inactivation， and the research progress of photodynamic inactivation in killing planktonic bacteria and biofilm bacteria are emphasized.

Abstract:Saccharomyces boulardii(S. boulardii)， a subspecies of S. cerevisiae， has a positive impact on intestinal homeostasis in humans and animals as a probiotic that can treat gastrointestinal diseases. S. boulardii has its own phenotypic characteristics and physiological properties. However， it is genetically close to the model yeast S. cerevisiae， and it has been discussed for a long time as an independent species or divided into S. cerevisiae variants. Therefore， this paper first reviews the main genetic differences between S. boulardii and S. cerevisiae. Secondly， its ability to adapt to host physiological conditions is summarized， clarify its unique biological activities， including the optimal growth temperature and the ability to survive in the acidic environment of the gastrointestinal tract， which are the basis of its success as a probiotic. In addition， elucidating their intestinal probiotic effects in terms of various biological functions such as antitoxin properties， competitive rejection of pathogens， regulation of intestinal microbiome， stimulation of the intestinal mucosal immune system and trophic effects. Finally， the application status and prospects of S. boulardii in feed and food were summarized. S. boulardii has great potential as a novel probiotic preparation for human health and companion animal industries.

Abstract:The fermented soy products which fermented with the protein-rich soy or soy meal， have unique flavors and good nutritional value. However， contaminations in the raw materials or formed during fermentation lead to high food safety risk. Recent studies showed that harmful amine (ammonia) metabolites， especially biogenic amines and ethyl carbamate， are widespread contaminated with high level in fermented soy products. At present， the main methods to reducing biogenic amines and ethyl carbamate include raw materials and starter cultures screening， fermentation process optimization， inhibitors addition during fermentation， and the usage of biochemical degradation. In this review， the contaminations of biogenic amines and ethyl carbamate in different fermented soy products were compared， the formation regulation and mechanism were discussed， and control strategies were analyzed with their effects on the quality and flavor of fermented soybean products. Since most of products are fermented in the semi-open environment， the process optimization and the usage of inhibitors are the alternative ways to reduce biogenic amines and ethyl carbamate， due to the advantages of low-cost， effectiveness and easy to operation.

Abstract:Chlorogenic acid (CGA) is a type of water-soluble phenolic derivatives with a variety of physiological functions， but its low lipid solubility limit CGA's industrial applicability. Molecular modification is an effective approach to synthesize chlorogenic acid derivatives (CAD) which have higher liposolubility and comparable bioactivities to CGA. In this paper， the preparation of CAD using chemical methods including the acyl chloride method and enzymatic methods， such as esterification and ester exchange are reviewed. The typical approaches for the isolation and purification of CAD are discussed. Besides， the recent advances in chlorogenic acid derivatives' bioactivities including the antioxidant， antitumor and antifungal functions， lipid metabolism regulation properties are evaluated. Finally， the current issues in CAD study and potential applicability in future are summarized.

Abstract:Galactomannan is a kind of neutral heteropolysaccharide， which has excellent abilities in thickening， stabilizing and gelling. Moreover， it has a variety of physiological functions， like promoting the proliferation of bifidobacterium in intestine， lowering blood pressure and blood sugar， and preventing constipation， colon cancer， cardiovascular disease. The properties differ in the ratio of mannose/ galactose units， molecular weight， and distribution of individual galactose branches along the main chain. With the development in the hydrocolloid industry， the modification of galactomannan has been an important research topic to ensure its use in food， pharmaceutical， biomedical and other fields. In recent years， there were many researches on galactomannan. The physical properties， physiological activity， modification and application of galactomannan were comprehensively introduced in this paper， in order to provide reference for the research of galactomannan in China.