Abstract:Jug r 2 is the major allergen of walnut. And the linear epitopes on Jug r 2 is a key factor in triggering a severe allergic reaction. Hence， the research on the efficient strategy for analyzing the linear epitopes of Jug r 2 is necessary. In our study， two immunoinformatic tools including DNAStar Protean and ABCpred were used to predict the B cells linear epitopes on Jug r 2. In vitro simulated gastrointestinal digestion and HPLC-MS/MS were used to identify anti-digestion peptides. And anti-digestion peptides were located on the 3D model of Jug r 2. The results showed that eight predicted B cells linear epitopes were AA186-199， AA226-230， AA257-263， AA284-289， AA373-382， AA389-398， AA408-414， AA472-487； eleven anti-digestion peptides were AA215~220， AA250~260， AA323~337， AA351~356， AA363~388， AA428~438， AA470~483， AA488~513， AA514~526， AA527~541， AA545~572. Of all anti-digestion peptides， four coincided with the predicted or true B cells linear epitope sequences and eight coincided with true T cells epitopes sequences. Anti-digestion peptides showed good antigenic properties in hydrophilic and flexible on the localization of Jug r 2 3D structure. Therefore， the anti-digestion property of food allergens may be a promising direction for studying linear epitopes of Jug r 2.

Abstract:In this study， the pre-treated whey protein by ultrasound was used as the substrate for enzymatic hydrolysis. OPA and ELISA method were used to analyze the optimal conditions of ultrasonic pretreatment - enzymatic hydrolysis for whey protein by the crude enzyme of Kluyveromyces marxianus Z17， in order to reduce the antigenicity of whey protein (characterized by the antigenicity of α-LA and β-LG). The results showed that the hydrolysis degree of whey protein was significantly affected by initial pH value and hydrolysis temperature， and the antigenicity of α-LA and β-LG was apparently influenced by initial pH value， and the interaction of ultrasonic interval time and ultrasonic power also played a role in affecting the antigenicity of α-LA and β-LG. The optimal conditions for enzymatic hydrolysis to transform whey protein by Kluyveromyces marxianus Z17 were obtained by response surface method: the reduction rates of α-LA antigenicity and β-LG antigenicity were predicted to reach the maximum at the ultrasonic interval time of 16 s， the ultrasonic power of 400 W， the initial pH of 6.16 and the enzymatic hydrolysis temperature of 18.48 ℃， which were 65.56% and 57.96%， respectively.

Abstract:Pectin is a polysaccharide that widely exists in plant cell walls and has a variety of physiologically active functions. Various studies have confirmed that modification of polysaccharide can improve its biological activity. Therefore， in this study， the citrus segment membrane pectin (PP) and its degraded oligosaccharides (POS1 and POS2) recovered from the citrus canning waste water were carried out sulfate esterification in order to increase their activity. Molecular weight and monosaccharide composition analysis showed that after sulfating by TBA and DMSO systems， the molecular weight of sulfated pectin polysaccharides and oligosaccharides were decreased， and the content of arabinose and galactose reduced significantly. FTIR and NMR results shown that the H4 of each component of galacturonic acid showed a low-field shift after sulfation. And the anomer hydrogen signals of galactose and arabinose from POS1 and POS2 shifted to the low field， respectively. Which indicating that the main chain and the side chain were sulfated. The in vitro results showed that the anti-tumor activity of sulfated POS1 and POS2 was further enhanced. Among them， POS1-T has the best effect， with an inhibition rate of 30.25%. In summary， the results of the study indicated that sulfation could increase the antitumor effect of pectin polysaccharide and its oligosaccharides.

Abstract:The stability in different temperature and pH value of soluble dietary fiber-polyphenol complexes and their functions on lipids， cholesterol， cholesterol decreases， adsorption capacity and cation exchange capacity of bile salts， also the potential lipid-lowering activity in vitro experiments were explored， which aimed at providing a reference for the preparation of functional foods with lipid-lowering function. The datas showed that the stability of the compound decreased with the increase of temperature and pH value. The adsorption capacity of soluble dietary fiber-polyphenol complex to oil was better than that of soluble dietary fiber and physical mixture， whose results were significantal (P<0.01) different and the adsorption of lard and peanut oil showed the same trendency. The adsorption effect of the complex on cholesterol was significantly better than that of soluble dietary fiber (P<0.05) the simulated environment solution (pH 7.0) and the adsorption capacity of the complex on cholesterol in the simulated intestinal environment (pH=7.0) was significantly higher in a simulated stomach environment (pH=2.0). In addition， the interaction between soluble dietary fiber and polyphenols significantly promoted the adsorption effect of soluble dietary fiber on cholate (P<0.01) and improved the cation exchange capacity of soluble dietary fiber.

Abstract:Objectives: To investigate photodynamic technology (PDT) inactivation of Grimontia hollisae (Gh) and Vibrio alginolyticus (Va) mediated by water soluble curcumin and its mechanism. Methods: The inactivation effect of Gh and Va by PDT was determined by colony counting method， reactive oxygen species (ROS) production in bacteria was tested by ROS assay kit， total protein degradation was analysed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and virulence gene damage was examined by agarose gel electrophoresis. Results: Water soluble curcumin PDT significantly inactivated Gh and Va. The inactivation effects increased with dark incubation time， illumination time and curcumin concentration. After PDT treatment， Gh and Va decreased by 7.98 lg (CFU/mL) and 7.80 lg (CFU/mL)， and the inactivation rate was over 99.99%. PDT promoted the ROS level in bacteria to degrade bacteria protein and DNA， but no significant damage to virulence genes of Gh and Va was observed. Conclusion: Curcumin PDT can effectively inactivate Gh and Va via ROS and shows potential application in aquatic food safety.

Abstract:Soybean peptides (SOPs) are functional ingredients with good health benefits. The health benefits presented are highly dependent on the peptide structures. SOPs were prepared from soybean protein isolate by hydrolysis. Ultraviolet full wavelength scanning method and circular dichroism spectrophotometry were used to analyze whether the structure of SOPs was affected by pepsin， trypsin and the sequential treatment of pepsin and trypsin. ABTS free radical scavenging ability， DPPH free radical scavenging ability， oxygen radical absorbance capacity (ORAC) and ferric ion reducing antioxidant power(FRAP) of SOPs were measured in order to explore the changes of antioxidant capacity of SOPs before and after digestion. The results showed that SOPs were mainly composed of components with molecular weight less than 1 000 u， and the proportion of components less than 1 000 u increased after digestion， and the maximum proportion reached 88.46%. They all had maximum absorption peaks at 275 nm. In the secondary structure, the proportion of random curl in the four groups of SOPs was about 30%， accounting for about 1/3 of the total secondary structure composition, indicating high disorder and loose and open structure of SOPs. The ABTS free radical scavenging ability and iron reducing ability of SOPs were stable. After trypsin digestion， DPPH radical scavenging rate decreased and oxygen radical absorption capacity increased significantly (P < 0.01).

Abstract:On the basis of establishing the simulated reaction system of non-enzyme gluco-sylation protein and reducing sugar in vitro， the inhibitory effect of turtle antioxidant peptide on non-enzyme gluco-sylation(NEG) reaction and advanced glycation end products (AGEs) was investigated. The results showed that the mass concentration of anti-oxidation peptide was 1.00 mg/mL， and the inhibition rate of NEG was 68.79% when incubated for 21 days， the inhibition rate of AGEs was 89.35% when incubated for 28 days. Infrared spectroscopy results proved that antioxidant peptide of turtle could effectively inhibit the production of AGEs in non-enzymatic gluco-sylation reaction.

Abstract:Calcium carbonate is a commonly used fortified calcium， but its suspension stability is poor and easy to precipitate， and this seriously limited its application in food processing. The formation of CaCO3 loaded microparticles based on the form of solid/oil/water(S/O/W) emulsion is a promising method to improve the dispersion stability of CaCO3 in liquid food. In this study， CaCO3， soybean oil， and sodium caseinate - gelatin were used as the soild， oil， and W phase， respectively. The particle size， physical stability， rheology and microstructure of microspheres prepared by different mass fractions of gelatin and different amount of S/O phase were studied， and the formation regularity and stability of S/O/W calcium-lipid microspheres were explored. The results showed that the stability of S/O/W emulsion could be improved by adding different mass fraction of gelatin， and the particle size of the emulsion decreased with the increase of gelatin mass fraction， the apparent viscosity and friction coefficient of the emulsion decreased， and the microstructure of the emulsion network became denser. Increasing the amount of S/O phase made the stability of the emulsion worse， the distribution range of particle size increased， and the apparent viscosity increased slightly. When the amount of S/O phase was higher， the brownian motion region of the particles was larger and the emulsion became less stable. The preparation of S/O/W emulsion by adding gelatin can improve the stability of the emulsion. This study lays a theoretical foundation for solving the dispersion stability of insoluble calcium salts in liquid food.

Abstract:In order to clarify the state and distribution of water in non-fermented frozen dough at different mixing times and during freezing storage， low-field nuclear magnetic resonance (LF-NMR) was used to determine the moisture state of dough and after freezing during the dough mixing process by farinograph. The results showed that: In the dough mixing process， the proportion of strongly bound water (A21) in the dough just after leaving 500 BU was the highest and the proportion of weakly bound water(A22) was the highest. At this time， the water binding state was the best， and the gluten was fully hydrated. Ice crystal pores with irregular shapes and uneven distribution appeared inside the dough with different stirring times after freezing. However， the A21 value of the dough that had just left 500 BU was still the highest after freezing， the number of internal ice crystal pores was small， and the area of ice crystal pores was small. The moisture binding state was better. Conclusion: The moisture binding state of the dough that just left 500 BU from the farinograph kneading process was the best， the gluten network structure was fully formed， and the mobility of internal water molecules was the lowest. After frozen storage， the moisture binding state of the dough that had just left 500 BU was still good， and the internal water molecules were relatively stable.

Abstract:The effects of mass concentration， temperature， inorganic cation type and pH on the fluid and gelation properties of polysaccharide from Dendrobium officinale(DOP) were evaluated by rheological analysis and FT-IR analysis in this study. The results showed that the DOP aqueous solution exhibited shear-thinning flow behavior under different concentration， temperature， inorganic cation type and solution pH. The viscosity of DOP solution increased with its increasing concentration and the pseudoplastic was more obvious. The viscosity of DOP solution decreased with the increasing of temperature in the range of 5~75 ℃. The addition of Na+ significantly increased the viscosity of DOP solution. However， the viscosity of DOP solution was decreased when K+， Ca2+， Al3+ were added respectively and the change trend was related to the inorganic cation concentration and valence. DOP extracted with hot water had good stability under acidic conditions. However， the viscosity of DOP solution significantly increased under alkaline conditions and the gelation of solution will be occurred under alkaline conditions (pH>10.0). The dynamic rheological results showed that the gel transition was enhanced with the increasing of polysaccharide mass concentration. The FT-IR results indicated that the gelation was related to the absorption peaks at 1 735 cm-1， 2 935 cm-1 and 2 881 cm-1. The above results suggested that the aqueous solution of DOP had unique fluid and gelation properties for processing. The results are useful for the formulation and processing of polysaccharide extracted from Dendrobium officinale.

Abstract:A novel GH16 β-porphyranase gene por16Z was cloned from marine bacterium Wenyingzhuangia aestuarii OF219 and expressed in E. coli， and the biochemical properties and hydrolytic patterns of the recombinant protein Por16Z_Wa were characterized. Por16Z_Wa showed the maximum activity at 45 ℃ and pH 6.5 and keep stable at a wide pH range from 4.0 to 9.0. Por16Z_Wa exhibited a cold-adapted property. Por16Z_Wa was an endo-acting enzyme. The final products of Por16Z_Wa were majorly composed of porphyran disaccharides L6S-G， with a minor portion of tetrasaccharides and hexasaccharides which were substituted by agarose moieties and (or) modified by methyl groups. Por16Z_Wa could be utilized as a promising tool for degradation of porphyran and directional preparation of porphyran disaccharides， which would facilitate the investigation of porphyran polysaccharides.

Abstract:Transglutaminase (TGase or TG)， one of the natural food cross-linking agents with strong cross-linking function， form network structures among proteins via ε-(γ-glutamyl)-lysine (G-L) bonds. The gene tgM of TGase was obtained from the genomic DNA of Cordyceps militaris through PCR amplification. It was inserted into an E.coli-P. pastoris shuttle vector pPIC9K to construct recombinant plasmid pPIC9K-TG. The recombinant TGase was successfully expressed in P.pastoris and secreted into the culture medium. In optimized fermentation conditions， the activity of TGase in fermentation broth was up to 100 U/L. The results could provide guidance for the heterologous expression and potential industrial application of TGase.

Abstract:In order to solve the protein instability problem of white wine and to realize the utilization of acid protease and alcohol fermentation simultaneously， this study used Saccharomyces cerevisiae haploid strain BY4741 and diploid strain 82-9-35 as hosts to express acid protease on the yeast cell surface by the action of promoter and anchor protein in the yeast surface display system. The acid protease gene(pepA) from Aspergillus usamii was cloned， a cell display cassette expressing acid protease was constructed， and homologous recombination was used to integrate the acid protease gene into the gene locus of S. cerevisiae. Through PCR and sequencing validation， two haploid and diploid recombinant strains with the highest enzyme activity of 285.71 U/mL and 495.24 U/mL， respectively， were obtained for the cell surface display of acid protease. This study successfully constructed a new idea of using SED1 as an anchoring protein display system to solve the protein turbidity problem in wine， and laid the theoretical foundation for the industrial application of pepA acidic protease whole cell catalyst.

Abstract:Intestinal tract is the major organ for digestion and absorption of food nutrients. The establishment of an effective intestinal ex vivo model is helpful to promote the development of a novel evaluation system for absorption and efficacy of food nutrients and functional active substances. Based on the intestinal crypt containing intestinal stem cells， we created an integrated set of organoid culture of different intestinal segments (including duodenum， jejunum and ileum) of mouse through optimizing the isolation method of intestinal crypt from different intestinal segment and the composition of culture medium. In addition， RT-PCR and immunofluorescence results demonstrated that the organoids derived from different segment recapitulate the structural characteristics and cell composition of corresponding intestinal tissues. These characters had high stability during in vitro repeated passage. In short， the establishment of orgnaoid culture of different intestinal segment may provide a promising ex vivo model for the evaluation of absorption and function of food nutrients in the food research field.

Abstract:The diversity of intestinal flora in ruminants plays an important role in the quality of animal meat. In this study， high-throughput sequencing was used to analyze the effects of Lactobacillus on intestinal flora composition and meat quality of Sunit sheep. Twelve 3-month-old healthy Sunit sheep were divided into two groups， one group was fed with basic diet， the other group was fed with 0.5% Lactobacillus and slaughtered after 90 days. The results showed that Bacteroidetes and Verrucomicrobia in the intestinal flora of the Lactobacillus group were significantly higher than the control group (P<0.05)， Lachnospiraceae NK3A20 group and Alistipes were significantly lower than the control group (P<0.05). In the Lactobacillus group， the redness value a* and luminance value L* were significantly higher than the control group (P<0.05)， the flavor substances such as hydrocarbons， ketones and esters were significantly higher than the control group (P<0.05)， the contents of amino acids and unsaturated fatty acids were significantly higher than the control group (P<0.05)， and the shear force was significantly lower than the control group (P<0.05). Lactobacillus added to feed could optimize intestinal flora composition of Sunit sheep， promote nutrient metabolism of the body and improve meat quality.

Abstract:Objectives: To study the protective effect of camel milk on alcoholic liver injury in mice induced by Lieber-DeCarli liquid diet. Methods: 40 male C57BL/6NCr mice were randomly divided into control group(Con)， model group (Et)， camel milk high-dose group (EtCM_H， 3 g/kg)， camel milk low-dose group (EtCM_L， 1.5 g/kg) and positive control group (Metadoxine， 300 mg/kg). The experiment was conducted for a total of 8 weeks. The first 4 weeks were only fed with special feed without gavage. After 4 weeks， the feeding method was unchanged， with milk or metadoxine by gavage， once a day. After intragastric administration， the NIAAA model was established by intragastric administration of 31.5% alcohol solution at a dose of 5 g/kg. The indicators of liver antioxidant and anti-inflammatory， apoptosis markers contents， serum transaminase activity were measured. HE staining was used to observe liver histopathological changes. Oil Red O staining was used to observe liver lipid accumulation. TUNEL staining was used to detect liver cell apoptosis. Results: Camel milk could significantly reduce the activities of serum alanine aminotransferase and aspartate aminotransferase in mice with liver injury， and reduce liver tissue malondialdehyde， triglycerides， and tumor necrosis factor-α (TNF-α)， interleukin-1β (IL-1β)， interleukin-6 (IL-6) content and Caspase-3 activity， improve the activity of superoxide dismutase in mouse liver tissue， reduce glutathione and interleukin-10 (IL-10) content， reduce lipid accumulation in the liver， reduce liver cell edema， and antagonize liver cell apoptosis. Conclusion: Camel milk has a protective effect on alcoholic liver injury induced by Lieber-DeCarli liquid diet in mice， and presents a dose-dependent characteristic. High dose is better than low dose. Camel milk may improve liver cell antioxidant capacity and increase the content of inflammatory factors to promote fat transport， and then restore the structure and function of liver cells to achieve this protective effect.

Abstract:Objective: To study the antioxidant activity and mechanism of mushroom complex polysaccharide (FHP). Method: The free radical scavenging efficiency in vitro and oxidative survival rate in C. elegans were used to evaluate the antioxidant capacity of FHP. The reactive oxygen species (ROS) level， malondialdehyde (MDA) content， antioxidant enzyme activity as well as the stress-related transcription factor activity and effector gene expression were used to study the antioxidant mechanism of FHP. Result: Compared with that of single polysaccharide， FHP exhibited higher free radical scavenging efficiency and stress survival rate increase， indicated a better antioxidant effect. Experiments in C. elegans showed that FHP could not only increase the survival rate of paraquat-stressed N2 nematodes， but also reduce the internal ROS level and MDA content. Further experiments revealed that FHP could also activate the nuclear translocation of stress response transcription factor SKN-1 and DAF-16 and increase that target gene expression， and these results were further verified in the examination of antioxidant enzyme activity. But FHP did not prolong the lifespan and reduce the lipofuscin level in N2 nematodes. Conclusion: FHP can effectively enhance the oxidative stress resistance of C. elegans， but not affect the aging. Its antioxidant mechanism may be related to the activation of transcription factors SKN-1 and DAF-16 and the influence on the downstream effector activity.

Abstract:Obesity is a chronic metabolic disease in which excessive accumulation of body fat leads to overweight. Cassava starch is a digestible starch， and the current research on it mostly focused on structural analysis and in vitro function evaluation. This study was based on a mouse obesity model， using high-throughput sequencing technology to study the total cholesterol (TC)， triglycerides (TG) and immune index immunoglobulin A(IgA)， immunoglobulin G (IgG)， immunoglobulin M (IgM) in the blood of modeled obese mice after ingesting cassava starch. Studies have shown that compared with the control group， the levels of TG， IgA， IgG， and IgM were significantly higher than those in the control group. Cassava starch intake it promoted the increase of the relative abundance of bacteria that could efficiently catabolize carbohydrates such as Bifdobacterium and Dorea， but also promotes the proliferation of pathogenic bacteria such as Clostridium. Ingestion of cassava starch promoted changes in the microbial composition of the gut tract of mice. At the same time， abundant carbohydrates also provided sufficient energy sources for the body， thereby increasing energy storage and making mice more prone to obesity.

Abstract:Through the establishment of D-galactose-induced senile osteoporosis (SOP) mouse model， the effect of Grifola frondosa polypeptide-calcium chelate (GPs-Ca) on SOP was explored. The calcium absorption promoting ability of Grifola frondosa polypeptide-calcium chelate was studied by Caco-2 single cell layer model in vitro. Fifty male ICR mice were randomly divided into 5 groups. Except for the blank control group， the other four groups were given intraperitoneal injection of D-galactose； the control group was given intraperitoneal injection of the same dose of normal saline. After 8 weeks， the model was successfully established. Both the control group and the model control group were given deionized water intragastrically； the treated group was given a high dose of Grifola frondosa polypeptide-calcium chelate (Hgps-Ca). After 4 weeks of continuous treated in each group， blood was collected to detect the blood biochemical indicators， and the femur and tibia were stripped to determine the bone indicators. A Caco-2 monolayer was established， and Fluo-3-Am calcium ion probe was used to measure intracellular calcium uptake. Serum calcium and phosphorus levels in the Hgps-Ca group increased significantly， with statistical significance (P<0.05)； serum alkaline phosphate (ALP) values of each group were lower than those in the model group， and the serum ALP level of Hgps-Ca group was close to that of the control group. GPs-Ca was more easily absorbed and transported in cells than inorganic calcium. The results showed that Grifola frondosa polypeptide-calcium chelate can improve serum calcium， phosphorus， CAT levels， reduce ALP activity， promote calcium salt deposition， improve calcium absorption and utilization rate， which is conducive to the treatment of SOP.

Abstract:Saccharomyces cerevisiae Y3401 with high-yield for ethyl caproate was selected， and the fermentation conditions of ethyl caproate from it were optimized. Firstly， the medium conditions (including initial pH value and sugar content) and induction conditions (including temperature， rotation speed， inoculation amount， ethanol addition amoun， caproic acid addition amount， pre-induced period， and post-induced period) were optimized by single factor design. Then， five significant factors for ethyl caproate production were screened by Plackett-Burman design， and the maximum response area was determined by the steepest ascent design. Finally， the optimal fermentation conditions of Y3401 for producing ethyl caproate were obtained by response surface methodology. The optimal conditions were as follows: sugar content 14 Brix， initial pH 7， inoculum size of 3.5%， ethanol content 8%， caproic acid content 0.059%， pre-induced period 30 h， and post-induced period 31 h incubated at 25 ℃ with 180 r/min. Under the condition， the yield of ethyl caproate reached 10.1 mg/L. These results are helpful for the application of S. cerevisiae Y3401 in Baijiu brewing.

Abstract:The effects of different infrared radiation (IR) temperatures (100， 110， 120 ℃) and radiation time (2.5， 5， 10 min) on the microbial population and quality of carrot powder with high bacterial load were firstly investigated， the effects of infrared radiation-freezing and infrared radiation-tempering treatment on the microbial population， color and carotenoid quality of carrot powder were further investigated according to the principle of the fence effect. Infrared radiation treatment at 100 ℃ and 10 min reduced bacteria， mold and yeast by 1.9 lg(CFU/g) and 2.32 lg(CFU/g)， respectively. Infrared radiation at 110 ℃ and 5 min reduced bacteria and fungi by 1.58 lg(CFU/g) and 2.57 lg(CFU/g)， respectively. The water activity of carrot powder decreased from 0.238 to 0.123 and 0.147， respectively. The total carotenoid content in carrot powder decreased from 308.8 μg/g to 227.8 μg/g and 238.8 μg/g， respectively. The total color difference (ΔE) was determined to be 9.11 and 7.89， respectively. Compared to IR treatment alone， combination of infrared radiation and tempering treatment on the effects of microorganism inactivation in carrot powder was weak， the total content of bacteria remained at 5.40-5.80 lg(CFU/g) after treatment. Mold and yeast counts were significantly reduced through treatment but was not lower than 4.5 lg(CFU/g). While， combination of infrared radiation (100 ℃ and 10 min) and freezing treatment (7 d) finally reduced the bacterial population of 0.25 lg(CFU/g)， while reduced the amount of mold and yeast of 0.28 lg (CFU/g). Under the condition of infrared radiation (110 ℃ and 5 min) and freezing treatment (7 d)， the contents of bacteria， mold and yeast were reduced 0.26 lg(CFU/g) and 0.40 lg(CFU/g). In these conditions， the color， water activity， and carotenoid content of carrot powder were not affected significantly. This experiment provides a reference for the study of infrared radiation combined sterilization of low moisture powder foods.

Abstract:Four thermal processing methods (normal pressure steaming， stir-frying， hot-air baking and microwave) were used to process Yunnan Dayao hemp seed. Taking the aroma of hemp seed as an indicator， explored the effects of four thermal processing methods on the composition of volatile flavor compounds， color， nutrients， and storage stability under the optimal aroma processing conditions. The results showed that the optimal processing conditions for the four thermal processing methods were respectively 8 minutes' atmospheric steaming at 100 ℃， 15 minutes' frying at 150 ℃， 40 minutes' hot air baking at 130 ℃ and 4 minutes' power microwave of 600 W. Untreated hemp seeds contained more alcohols such as 2-3 butanediol (10.21%) and 1-hexanol (7.92%). Four thermal processing methods could increase the types and content of volatile flavor substances， among which stir-frying treatment and hot-air baking could significantly increase the content of aldehydes and heterocyclic substances. There were significant differences in color， protein， total sugar， ash， fat， total phenol， total flavonoid content and unsaturated fatty acid ratio of hemp seed with different thermal processing methods being tried (P<0.05)， and after applying the microwave treatment proteins there was a higher level of content remaining such as total phenols and total flavonoids. Steaming and hot-air baking could help retain a higher proportion of unsaturated fatty acids， of which the retention rate of linolenic acid was the highest， 92.64% and 98.73%， respectively. Fire treated with different heat processing hemp seed had a significant inhibitory effect on lipoxygenase (P<0.05)， and could inhibit fat oxidation during short-term storage. The above-mentioned research on physical and chemical properties would make a good reference for the deep processing and utilization of hemp seed.

Abstract:The objective of this study was to obtain the optimal technology of ultrasonic-assisted extraction of collagen from camel skin， and the extracted collagen was characterized and analyzed. In the experiment， the extraction rate of collagen was used as an indicator to explore the effects of enzyme loading， solid-liquid ratio， ultrasonic power， ultrasonic treatment time and total extraction time on camel skin collagen. After determining the ultrasonic power， on the basis of one-factor-at-a-time method， combined with response surface analysis， the best extraction conditions: enzyme loading of 4.5%， solid-liquid ratio of 1∶23， ultrasonic treatment time of 20 min， total extraction time of 51 h， and the actual extraction rate of collagen was (41.99±1.57) %. The SDS-PAGE analysis suggested that the extracted collagen contained three characteristic chains of type I collagen. Ultraviolet spectroscopy analysis was further inferred to be a typical type I collagen. The Fourier transform infrared spectroscopy analysis confirmed that collagen had a complete triple helix structure. Scanning electron microscopy observation revealed that the extracted collagen was in the form of fibrous with intertwined structure. Meanwhile， the Zeta potential of pH 2~9 of collagen was measured， and the potential value showed a downward trend in this range. The isoelectric point was 6.7.

Abstract:The effects of different rinsing techniques on the gel property of prawn ball were studied with white-hair rough shrimp(Trachypenaeus curvirostris) and white shrimp (Penaeus vannamei) as raw materials， and the formula was optimized. The best rinsing process for shrimp meat was water ratio 11∶1 and rinsing time 7 min， taking gelation strength， elasticity and adhesive strength as indicators. The fuzzy comprehensive evaluation and response surface methodology (RSM) results showed that the optimal solution was as follow: 5.6% potato starch， 25% white shrimp and 1.9% salt， taking sensory score as indicator. This study can provide data support for the improvement of processing technology of white-hair rough shrimp products and prawn ball products.

Abstract:ArabiNO_xylan was extracted from wheat bran and added into fresh wet noodles. The rheological properties of gluten protein in flour， the gelatinization properties of starch as well as the cooking and textural properties of noodles were measured to analyze effects of different mass fractions of wheat bran arabiNO_xylan (WBAX) on the properties of fresh wet noodles. The results showed that the addition of WBAX has a weakening effect on the formation of gluten. However， as the addition of WBAX increased， the peak viscosity and final viscosity in starch grew up， the disintegration value of the gelatinization process reduced， the dry matter loss rate of the noodles decreased， and the water absorption， hardness and chewiness of the noodles increased. Higher addition of WBAX (3% and 4%) limited starch swelling and reduced its cracking， and 4% WBAX had the best effect on improving the properties of fresh wet noodles.

Abstract:Penthorum chinense Pursh (PCP) is a functional new food material traditionally used as herbal substitutional tea， with strong bitterness and unpleasant smell. In the present work， the influence of PCP leaf tea processing on its sensory qualities were studied using response surface methodology (RSM) combined with Fuzzy Math Evaluation， and the optimized processing conditions were obtained as follows: baking moisture 60%， primary dry temperature 124 ℃ and rolling time 18 min. The results of amino acid composition analysis， UV-VIS and HPLC showed that the optimized processing decreased the contents of bitter amino acids in PCP leaf tea liquid and gallic acid， and gallic acid could be the main bitter taste ingredients in PCP leaf. HS-SPME and GC-MS investigation showed that PCP leaf showed the odor similar to green grass， orange oil， flowers and fresh scent， and the preparation of PCP leaf tea increased the fresh scent and flower fragrance of PCP leaf. Besides， the preparation of PCP leaf tea had no significant influence on the dissolution of the total flavonoids， quercetin and pinocembrin.

Abstract:To explore the bactericidal effect of dimethyl dicarbonate(DMDC) on foodborne harmful microorganism， the bactericidal effect of DMDC on the planktonic and biofilm bacteria of Pseudomonas fluorescens and Pseudomonas lund of spoilage organism in fresh food were comparatively evaluated in the present study. Effects of DMDC on the bacterial activity， intracellular enzyme activity and mature biofilm of Pseudomonas were measured by using API ZYM kit， XTT kits and confocal microscope. Meanwhile， antibacterial activity of DMDC at different mass concentration in tomato and lettuce were performed. The results showed that DMDC had stronger bactericidal action against the two Pseudomonas compared with other three pathogens. The two Pseudomonas were inactivated by 250 mg/L DMDC treatment for 5 min， which was attributed to the decreasing activities of alanine araminase and naphthol-AS-BI-phosphohydrolas. In addition， mature biofilm of P. fluorescein and P. lund could be effectively destroyed. The population in biofilm cell decreased by 4.60 lg (CFU/cm2) and 4.15 lg(CFU/cm2)， respectively， and the cell activity significantly dropped， resulting in the increase of dead cell and the thinner biofilm structure， when treated by 250 mg/L DMDC. Moreover， the aerobic plant count (APC)， Pseudomonas number (PA)， and mold and yeast count (MYC) of tomato and lettuce were significantly reduced by treatment of DMDC at 250 mg/L. The APC and PA in tomato was reduced by 2.60 lg (CFU/cm2) and 1.73 lg (CFU/cm2)， and in lettuce was decreased by 2.56 lg(CFU/cm2)and 1.98 lg(CFU/cm2)， respectively， for 15 min treatment， accompanied by no detection of mold and yeast after 5 min treatment. Sensory qualities were not affected. Thus， DMDC significantly killed the planktonic and mature biofilm of two Pseudomonas， and has a good bactericidal effects when applied to the surface of two kinds of fruits and vegetables， which is expected to become a new cleaning agent in fruit and vegetable.

Abstract:In this article， the collagen is extracted from swim bladder of grass carp (Ctenopharyngodon idella) by enzymolysis and its self-assembly is conducted. Composite film was made from self-assembled collagen， chitosan and glycerinum， and its properties were analyzed. Moreover， the effects of coating film on squid quality during cold storage were investigated. The results showed that collagen extracted from grass carp swim bladder belong to type I collagen and had a triple helix structure. The tensile strength of the film made from self-assembled collagen increases， and its elongation at break and water vapor transmission decrease. In addition， the spoilage of untreated squid was occurred on the eighth day， at the time the quality of squid treated with film made from self-assembled collagen was kept well. The values of TVB-N， microbial counts， K value and trimethylamine of squid treated after self-assembled collagen stored for 14 d at 4 ℃ were 21.53 mg/100 g， 5.67 lg(CFU/g)， 14.33% and 25.87 μg/g， respectively， which meant that coating film made from self-assembled collagen could slow down the corruption of squid and prolong the shelf life.

Abstract:In order to research the inhibitory effect and mechanism of plant extracts on the biofilm of Pseudomonas luteola. The effects of 6 kinds of extracts， such as dandelion， honeysuckle， clove， cinnamon， mint and mulberry leaf， on the biofilm formation of Pseudomonas luteola were measured. The clearance rate and inhibition rate of biofilm were calculated. The results showed that the extracts of dandelion and honeysuckle， which contains the same functional components - chlorogenic acid (CA)， has the best inhibitory and scavenging effects on the biofilm of Pseudomonas luteola. Under the action of chlorogenic acid， the amount of biofilm was determined by crystal violet method， the metabolic activity of biofilm was determined by MTT method， and the apparent morphology of biofilm was analyzed by laser confocal scanning electron microscopy. CA had a significant inhibitory and scavenging effect on Pseudomonas luteola. The metabolic activity of biofilm was reduced under the action of CA. High concentrations of CA prevented the bacteria from conglutinating to form biofilm. The bacteria could form biofilm at low concentrations， but the stereoscopic property of the structure was low. Conclusion: CA from the plant extract could inhibit the formation of biofilm by inhibiting the growth of bacteria， weake the three-dimensional structure of mature biofilm， and have the ability to clear biofilm

Abstract:In this study， blueberry anthocyanin (BA) as the freshness indicator， corn starch (CS) and carboxymethyl cellulose(CMC) were used as film-forming substrates to prepare smart indicator films by casting. The effects of different mass fraction of anthocyanins on the mechanical properties， moisture content， water vapor transmittance， thermal stability， infrared spectrum， surface microstructure and sensitivity of the composite film were analyzed and compared. The results showed that when the BA mass fraction was 3%， the elongation at break of the indicator film was the highest， the moisture content and water vapor transmission rate were the lowest， and the sensitivity was the best. When the BA mass fraction was 18%， the tensile strength was the highest， and the thermal stability was the best. Fourier transform infrared spectroscopy and scanning electron microscopy showed that the BA had good compatibility with the other two film-forming substrates and could improve the intermolecular compatibility. The indicator film was used to monitor the freshness of beef at 25 ℃. The total volatile basic nitrogen content was 15.94 mg/100 g after 24 h， indicating the occurrence of beef spoilage. At the same time， the color of the indicator film changed to light purple， and changed to light blue after 48 h storage. The research results could provide reference for the development and application of blueberry anthocyanin intelligent indicator films.

Abstract:The microbial community structure of traditional Koumiss is bound to be different because of the microenvironment and production process of each family. In this paper， using Pacbio SMRT sequencing technology， based on lactic acid bacteria specific primers， the lactic acid bacteria flora of fresh mare milk and Koumiss in Zhaosu County and Akto County， Ili Kazak Region， Xinjiang were explored. The results showed that the alpha diversity of lactic acid bacteria in fresh mare milk was significantly higher(P<0.005) than Koumiss， and the lactic acid bacteria in fresh mare milk were more abundant. Lactobacillus helveticus (35.52%)， Streptococcus salivarius (10.11%)， Lactococcus lactis (9.49%)， Streptococcus thermophilus (5.96%) and Lactobacillus delbrueckii (5.37%) were the main species of lactic acid bacteria in fresh mare milk. The main lactic acid bacteria species in Koumiss were Lactobacillus helveticus (61.77%)， Lactobacillus kefiranofaciens (14.91%) and Lactococcus lactis (9.76%). Staphylococcus saprophyticus(4.45%) and Staphylococcus aureus (2.62%) whose content in fresh mare milk were significantly higher than Koumiss (P<0.05) were pathogenic. In addition， other pathogenic bacteria were detected in fresh mare milk， such as Streptococcus mitis， Streptococcus agalactiae， Streptococcus gallolyticus， Streptococcus pasteurianus and Streptococcus lutetiensis， which stated that fresh mare milk should not be drink directly. And compared with fresh mare milk， Lactobacillus helveticus and Lactobacillus pontis with higher content in Koumiss were significantly positively correlated (r = 0.582， P<0.01). The results of beta diversity stated that fresh mare milk and Koumiss had different lactic acid bacteria flora characteristics， and the dispersion of Koumiss was higher than fresh mare milk， indicating that the quality of traditional Koumiss was uneven. The lactic acid bacteria specific primers used in this article provide better conditions for mining low-abundance lactic acid bacteria， which provides a more adequate theoretical basis for the industrial production of Koumiss.

Abstract:The unique flavor and health-care function of koumiss are closely related to its complex microbial structure. In this study， metagenomic technology was used to analyze the microbial diversity and functional genes of koumiss. The results showed that 30 phyla， 331 families， 913 genera and 2 692 species were identified. The dominant strains were Lactobacillus kefiranofaciens， Lactobacillus helveticus， Citrobacter freundii， Raoultella ornithinolytica， Citrobacter werkmanii and Lactococcus lactis. 10 849 and 214 338 genes were respectively annotated by COG and KEGG databases， the prominent pathways were carbohydrate metabolism and amino acid metabolism， followed by metabolic activities such as co-enzyme factor and vitamin metabolism and nucleotide metabolism. After CAZy database annotation， the number of glycolytransferases (1 238) and glycolytic hydrolases (1 430) was the highest， accounting for 76% of the active carbohydrate enzymes of koumiss. At the same time， three RRT12 proteases， two serralysin metalloproteinases， type 6 protein secretion system (T6SS) genes， 232 peptide transport systems and 231 peptidase control genes were found in koumiss， which showed strong protein decomposition and transport potential. Further， there were 26 ArAT genes， 40 ketoacid invertase genes， 51 AlcDH genes， 68 AldDH genes and 34 aes genes encoded in koumiss， which have the basis of forming strong flavor substances from amino acids.

Abstract:Okra is rich in viscous polysaccharide. This paper intended to study the effects of different drying methods on the structure and antioxidant properties of okra polysaccharide. After the okra raw material dried by hot air， natural drying and vacuum freeze-drying， the water-soluble polysaccharide was prepared by water extraction and alcohol precipitation method. Then， the basic physicochemical properties， monosaccharide composition， infrared spectrum， viscosity and antioxidant properties of okra were compared and analyzed. The results showed that the three polysaccharides were mainly composed of type I rhamnogalacturonan (RG-I) pectin， but with different linearity. Infrared spectra of the three polysaccharides were similar， while the solid morphology and molecular weight distribution were different to some extent. By measuring the apparent viscosity， it was found that the three polysaccharides had weak gel properties at a certain mass fraction， among which the polysaccharide viscosity was the highest in okra dried by hot air. In addition， the three polysaccharides all had certain ability of scavenging DPPH free radical， hydroxyl free radical and chelating metal ion， among which the antioxidant ability of okra polysaccharide was the strongest after natural drying treatment in vitro. In conclusion， the polysaccharides obtained from okra through the above three drying methods have their own characteristics， and the final drying method of okra can be determined according to the purpose of the final polysaccharide.

Abstract:Triacylglycerols (TAGs) and free fatty acids compositions of broccoli seed oil were analyzed using ultra-performance convergence chromatography (UPC2) combined with quadrupole time-of-flight mass spectrometry(Q-TOF MS) and gas chromatography (GC) combined with mass spectrometry(MS). A total of 43 different TAGs were characterized based on their Q-TOF MS accurate molecular weight and MS2 fragment ion profiles in the broccoli seed oil. There were 13 pairs of isomers in 43 TAGs. ELE， ELnE and GLnE were the three major TAGs. Among all TAGs， 15 TAGs contained erucin， contributing about 77.99% of the total TAGs. For the fatty acid compositions， erucic acid was the greatest fatty acid in broccoli seed oil， followed by oleic acid and linoleic acid. The chemical compositions of TAGs and fatty acids could promote the understanding about the chemical profiles of broccoli seed oil， thus improve the potential availabilities of developing function foods with broccoli seed oil in the future.

Abstract:Objectives: This paper focused on evaluating and exploratory analyzing applicability of multifrequency amplitude pulse electronic tongue in determination of sodium metabisulfite in shrimp. Methods: The extract of shrimp (Penaeus vannamei) with 20% alcohol aqueous solutions was subjected to signal acquisition of electronic tongue. Once electrode combinations were determined， extreme points， inflection points and fusion of extreme points with inflection points in resulting signals were used as feature to prepare corresponding dataset. Data were processed by different chemometrics approaches including principal components analysis(PCA)， partial least squares(PLS)， principal components regression (PCR) and artificial neural network(ANN). Their performances were evaluated by predicted values vs measured values plots， root mean square error and correlation coefficient. Results: The best electrode combination was determined as Pt (1 Hz)， Au (100 Hz)， Pd (10 Hz) and Ag (100 Hz). Inflection points exhibited a good performance in both qualitative classification and quantitative forecasting， while ANN performed best for regression models among three algorithms. ANN model using inflection points data possessed a RMSE(TE) of 0.106 and R2(TE) of 0.996 in test dataset， suggesting its effectiveness in predicting concentrations of sodium metabisulfite with advantage in both data size and predicting performance. Conclusions: It is feasible to determine concentrations of sodium metabisulfite by multifrequency large amplitude pulse electronic tongue. This study provided an alternative way for high throughout determining illegal addition of sodium metabisulfite.

Abstract:A method of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) to test stable carbon isotope ratio offormaldehyde(FA) in squid was established. After the squid samples were fully extracted with water， the oil was removed by centrifugation at high speed. The supernatant was derivatized with 2， 4-dinitrophenylhydrazine at 60 ℃ for 1 h. The derived liquid was extracted with n-hexane liquid. Dichloromethane， methanol， n-hexane and acetonitrile can be used as solvents for isotopic testing of formaldehyde 2，4 dinitrophenylhydrazone. No carbon isotope fractionation occurred in the derivative reaction of formaldehyde. The standard deviation of δ13C value of formaldehyde 2，4-dinitrophenylhydrazone from measured value and calculatedvalue by the mass balance equation was 0.215‰. The formaldehyde content of squids from 9 cities was 0.341-39.132 mg/kg， and the content in visceral was higher. The difference value of δ13C value in sample 2， 3， 4 and 5 with high formaldehyde content was as high as 23.653‰. The fingerprint of formaldehyde stable carbon isotope in aquatic products can be used as the characteristic index of source analysis.

Abstract:In this work， response surface methodology was used to optimize the fermentation medium components of E. cristatum FS-10 producing antibacterial active substances. Meanwhile， the antibacterial activity products were isolated and preliminary identification through highperformance liquid chromatography (HPLC)， matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and Fourier transform infrared (FT-IR) spectrometry. The results showed that the optimal medium components were determined as follows: anhydrous glucose (carbon source) 7.5%， sodium nitrate (nitrogen source) 0.65%， and potassium chloride 4.5%. Under the optimized fermentation conditions， the bacteriostasis rate reached 54.4% against the suspension of Psychrophile bacteria(1×105 CFU/mL). Two antibacterial active components(FS-IV and FS-VI) were isolated and identified. The molecular mass of component FS-IV and FS-VI were 1 630.8 u and 840.5 u， respectively， which might imply the existence of heteropolysaccharide derivative compounds and amide derivative compounds. Antibacterial compounds could inhibit the growth of some foodborne bacteria， including Pseudomonas， Shewanella and Psychrophile. They were stable to heat and acid-base conditions.

Abstract:Flavonoids are a kind of polyphenolic compounds with 2-phenyl flavone structure， which are widely found in fruits， vegetables and tea leaves， and have the functions of anti-oxidation， reducing blood lipids， regulating blood glucose and inhibiting inflammation. Numerous studies have corroborated that the metabolic absorption and physiological function of flavonoids in vivo are closely related to gut microbiota. In this paper， we elucidated the interaction between flavonoids and gut microbiota from the structure and function of gut microbiota， types and products of microorganisms involved in metabolism， types and activities of metabolic enzymes and other aspects， summarized the mechanism of flavonoids in preventing obesity， diabetes， irritable bowel syndrome， cardiovascular disease and Alzheimer's disease by regulating gut microbiota， so as to provide theoretical basis for the application of flavonoids in functional foods.

Abstract:Obesity is associated with an increasing tendency which is a typical metabolic syndrome resulting from metabolic disorders due to the excessive food intake， and thus leading to a citical threat to human health. Studies were proved that food reward was an important factor affecting feeding behavior and played a key role in the occurrence and development of obesity. Recent studies indicated that brain-gut peptide， leptin， insulin and gut microflora could directly or indirectly regulate appetite and stabilize body weight through dialogue between intestine and brain， which mediated a crucial role in preventing obesity. Therefore， this review highlighted the role of the dialogue between intestine and brain in food reward and expanded strategies for the prevention and treatment of obesity.

Abstract:Frying is a traditional food processing method， which is widely used in home cooking and food industry. The process of frying is complicated and violent. If not properly controlled， it is easy to generate some processing hazards， thus adversely affecting the health of consumers. This paper mainly introduced the latest research progress of several typical hazardous substances in fried food， including the formation pathways， influencing factors， potential hazards and control measures of trans-fatty acids， acrylamide， polycyclic aromatic hydrocarbons and heterocyclic amines， in order to provide scientific guidance for the reasonable adjustment of consumer's diet structure and the transformation and promotion of fried food industry.

Abstract:Bacteria utilize quorum sensing system to exchange intraspecific and interspecific information and regulate the physiological characteristics， including the biofilm formation， movement， secretion of toxins， production of bacteriocins and antibiotics. Therefore， quorum sensing system runs through the whole process of bacterial growth and reproduction， and plays an important role in the stability of bacterial population. Recently， more and more quorum sensing systems have been discovered and studied， and their regulatory mechanisms have been elucidated gradually， providing the foundation for the practical application of quorum sensing systems. In this paper， four kinds of bacterial quorum sensing systems were reviewed， and those of typical strains were analyzed. In addition， the quorum-sensing inhibitors and the quorum quenching mechanisms were summarized. The purpose of this paper was to provide a reference for the further study of the regulation mechanism of quorum sensing system and the development of new antibacterial agents.

Abstract:Sialic acid is an acidic monosaccharide with a 9-carbon skeleton， which is usually located at the end of non reducing oligosaccharides. Human milk is rich in sialic acid， which plays an important role in promoting the brain and cognitive development of infants and young children， antivirus and other aspects. At present， sialic acid is mainly prepared by microbial fermentation in industry. This paper analyzed the principle， method and prospect of sialic acid in infant food from the aspects of its properties， distribution， function and preparation methods， so as to provide theoretical support for improving the application of sialic acid in maternal and infant food.

Abstract:Burdock is a kind of plant with excellent food and nutritional value， commonly known as "Orient Ginseng". Burdock root is rich in inulin， dietary fiber， chlorogenic acid and other bioactive constituents， which possesses physiological functions such as lowering blood fat and blood sugar， anti-cancer， antibacterial， anti-inflammatory and liver protection. The objective of this paper was to summarize bioactive components， nutritional effects and the current status of deep processing in burdock and to provide scientific basis for the precise processing of its functional ingredients， and propose a theoretical support for the further development and utilization of burdock root resources. It also could outlook future research directions and application prospects and supply new insights into the early prevention of chronic non-communicable diseases of obesity， hyperlipidemia， type 2 diabetes， and colitis.