Abstract:Pectin is widely used as a health food colloid with its demand growth for years. Recovery of pectin from the process water of mandarin canning is the important new way for pectin production. The different parameters in canning process， such as fruit size classification， acidic and alkaline process for segment membrane removal， will affect the following recovered pectin. Thus， pectin extraction from mandarin segment membrane with three fruit sizes （diameter of 7.3-7.7， 5.9-6.3 cm and 5.0-5.4 cm）， under three extraction processes， that is， high temperature acidic extraction （commercial pectin process）， low temperature acidic extraction （mandarin canning acidic process）， and low temperature alkaline extraction （mandarin canning alkaline process） were conducted. The results show that the extraction methods significantly affect pectin properties. Low-temperature alkaline extraction pectin has the highest of neutral sugar content and molecular weight， while high temperature acidic extraction pectin ranks the lowest of the above indexes. The fruit size has a small influence on the pectin. Large mandarin contains less acid soluble pectin and more alkali soluble pectin comparing to the small mandarin. In addition， the molecular weight of large mandarin pectin is smaller. Thus， extraction method and mandarin raw material differences will affect the properties of pectin. This work provides an important knowledge for pectin extraction.

Abstract:Pulsed light is a novel non-thermal sterilization technology. In order to study and predict the sterilization effect of pulsed light on Aspergillus flavus （A. flavus） spores， A. flavus spores on solid medium were treated by pulsed light with intensities of 2.86， 1.60， 1.08 and 0.93 W/cm2 from 1 s to 60 s. Micro morphology of the spores with and with out treatments were observed by scanning electron microscope（SEM）. Log-linear model， Weibull model and Weibull+tail model were used to fit the kinetics model. The results showed that with the increase of irradiation intensity and time， the inactivation effect of pulsed light on A. flavus spores was enhanced. After 19 s of treatment under intensity of 2.86 W/cm2， all the spores with initial population of 5.15 lg（CFU/mL） were inactivated. SEM demonstrated the structure of spores collapsed after the treatment. Compared with the Log-linear model， both Weibull+tail model and Weibull model could fit the inactivation curves better （R2>0.95）. But Weibull+tail model was more accurate （R2=0.9727）.

Abstract:Zein was known by good film-forming property， but zein film mechanical properties problem affect its effectiveness in practical applications， modification was the effective way to solve the problem. In this paper， acetic acid， lactic acid， succinic acid， malic acid， tartaric acid and citric acid were used to modify zein. When the zein content was 0.1 g/mL； the ethanol volume fraction was 90%； the carboxylic acid amount was added 0.03 g/mL； the alkali-modified solution pH was 5.0； the reaction temperature was 60 ℃； the reaction time was 30 min. The results showed that non-alkali malic acid modified zein film extending rate was （228.17 ± 26.53）%， which increased 154% compared to the control group， but its tensile strength was only （0.70 ± 0.05） MPa. Alkali catalytic citric acid modified zein film tensile strength increased from （7.18 ± 0.54） MPa to （12.73 ± 1.05） MPa， its extension rate was （3.65 ± 0.21）%， which had no significant difference with the control group. The modified zein film had good mechanical properties which not only laid a foundation for its application in food preservation， but also facilitated the extension of China’s corn industry chain and promotes industrial maturity.

Abstract:In food industry， emulsifiers are commonly used to control the physical properties and processing properties of plastic fats， where glyceride monostearate （GMS） is widely used as emulsifier. The effects of GMS （1%， 2% and 4%） on SFC， hardness， and microstructure of palm stearin were investigated at different temperatures， respectively. It was observed that SFC and hardness of palm stearin with/without GMS remarkably decreased with the increase of temperature. The influence of GMS on SFC of palm stearin was more obvious at higher temperature （21.1-33.3 ℃）， and when the amount of GMS in palm stearin was higher than 1%， SFC of palm stearin increased as the concentration of GMS increasing. When the temperature ranged from 15 ℃ to 30 ℃， the hardness of palm stearin containing 4% GMS was significantly higher than those of the other samples， and more small fat crystal and denser crystal network was formed. The results showed that when the temperature was higher than 30 ℃， the addition of GMS could increase SFC and hardness of palm stearin， and reduce the size of fat crystals to form a denser network， which provides an effective basis for the storage， transportation and quality improvement of palm stearin-based plastic fats in higher temperature season.

Abstract:The aim of this study was to investigate the effect of sweeping frequency ultrasound pretreatment duration on the antioxidant activity of peptides prepared by β-lactoglobulin. The ultrasound pretreatment of different duration （0， 10， 20， 30， 60， 90 min） impacts on β-lactoglobulin （β-LG） hydrolysis and structural characteristics. The enzymatic hydrolysis characteristics of β-LG， such as the antioxidant activity， the surface hydrophobicity， the molecular weight distribution and the composition of amino acids of β-lactoglobulin hydrolysates were studied. The particle size， surface hydrophobicity and microstructure of β-LG after sweeping frequency ultrasound pretreatment were also determined. The results showed that sweeping frequency ultrasound pretreatment significantly improved the DPPH· scavenging rate， ABTS· scavenging rate and Fe2+ complexation rate. The antioxidant activity of β-LG hydrolysates increased significantly （P<0.05） with short time ultrasound pretreatment and decreased over a longer period （60，90 min）. After sweeping frequency ultrasound pretreatments， the surface hydrophobicity of enzymatic hydrolysates increased which indicated that more hydrophobic substances were released and polypeptides with molecular weight 200-2 000 u increased significantly which improved the antioxidant activity of β-LG hydrolysates. The amino acid profile analysis indicated sweeping frequency ultrasound pretreatment could increase the concentration of hydrophobic amino acids of the β-LG hydrolysates. Short time （< 30 min） ultrasound induced the particle size largely increased. After long-time sweeping frequency ultrasound （60， 90 min） treatment， the particle size of β-LG increased， which indicated that the exposed tryptophan residues aggregated into the protein.

Abstract:Based on the phenomenon that the passivation rate of ultrasonic wave on polyphenol oxidase and peroxidase in mango juice was significantly lower than that on mango crude enzyme solution， the possible factors affecting the passivation effect of ultrasonic wave were discussed by adjusting the content of food components and medium viscosity in the crude enzyme solution. The treatment conditions were 45 ℃， 799.31 W/cm2 and 15 min. It was found that the passivation rates of PPO and POD by ultrasound in crude enzyme solution with a sugar content of 5.0-20 Brix were decreased by 20.67%-29.36% and 40.34%-46.22% （P＜0.05） respectively， compared with the original crude enzyme solution with a sugar content of 4.4 Brix. Similarly， the passivation rates of PPO and POD by ultrasound in crude enzyme solution with an additional amount of 0.5%-2.5% were decreased by 24.55%-30.9% and 42.36%-47.19% （P＜0.05）， respectively， compared with the original crude enzyme solution. The viscosity of the crude enzyme solution was adjusted by adding different thickeners， it was found that the passivation rates of PPO and POD by ultrasound in crude enzyme solution with the viscosity of 17.6-27.1 mPa·s were decreased by 27% and 30% （P＜0.05）， respectively， compared with the unadjusted group with viscosity of 15.2 mPa·s， but the ultrasonic inactivation effect among different thickeners was similar （P＞0.05）. The pH of the crude enzyme solution was adjusted by adding citric acid， it was found that the passivation rates of PPO and POD by ultrasound in crude enzyme solution with the pH of 4 and 5 were decreased by 22.73%-27.19% and 34.58%-41.32% （P＜0.05）， respectively， compared with the unadjusted group with pH of 5.2. The results indicated that food components， pH and medium viscosity could affect the enzymes inactivation ratio of ultrasound.

Abstract:The purpose was to explore the structural characteristics and physicochemical properties of different varieties kidney bean starch and resistant starch. Using kidney beans as raw materials， kidney beans starch and resistant starch were prepared by alkaline method and autoclaved enzymolysis respectively， the molecular structure and physicochemical properties of them were studied by scanning electron microscope， Fourier infrared spectrometer， RVA viscosity meter， etc. The results showed that compared with the original starch， the morphology and crystal structure of the resistant starch particles changed； the functional groups and chemical bond composition of kidney bean starch were the same as resistant starch. Red kidney bean starch had the lowest gelatinization temperature， higher final viscosity and higher regeneration value. Compared with starch， the gelatinization temperature of each resistant starch significantly increased， and the paste viscosity decreased. The solubility and swelling of kidney bean starch and resistant starch were all related to temperature with a positive correlation， and the freeze-thaw stability of kidney bean resistant starch decreased. Conclusion： Different varieties of kidney beans have the same molecular structural characteristics and different physical and chemical properties； autoclaved enzymatic hydrolysis changes the morphology and crystal structure of resistant starch granules； different varieties of kidney beans have different physical and chemical properties.

Abstract:O-benzoquinones， generated by the oxidation of polyphenols， are highly electrophilic compounds and may react with many kinds of nucleophiles in food systems， and therefore cause nutrient losses and food safety problems. The interaction of quercetin quinone with five kinds of amines， two kinds of thiols and bovine serum albumin （BSA） were investigated at pH 5.0， 7.0 and 8.0 by electrochemical workstation. Quercetin quinone reacted with selected nucleophiles more efficiently at pH 7.0 and 8.0 than that at pH 5.0. In addition， reaction of quercetin quinone with thiols was found to be faster than that with amines. At pH 7.0 and scan rate of 10 mV/s， amines（16.0 mmol/L） reaction with quercetin quinone （0.08 mmol/L） followed the order： L-lysine （55.13% ± 5.37%） > L-arginine （39.58% ± 4.64%） > L-methionine （17.80% ± 2.72%） > glycine （~0.00%）≈Nα-acetyl-L-lysine （~0.00%）. Thiols （0.048 mmol/L） reaction with quercetin quinone （0.08 mmol/L） under the same conditions followed the order： L-cysteine （63.17% ± 1.51%） > Nα-acetyl-L-cysteine（54.28% ± 2.60%）>BSA （37.55% ± 5.98%）. These data proved that O-benzoquinone formed by the oxidation of quercetin could modified proteins and eliminated essential amino-acids.

Abstract:Objective： This study was undertaken to determine the effectiveness of tea polyphenols （TP） in preventing cadmium chloride（CdCl2） induced hepatotoxicity and hematotoxicity in mice. Methods： Eight-week-old male Kunming mice were chosen. Control， Cd-treated （a single injection of 30 μmol/L Cd2+/kg， i.p.）， Cd + TP （after Cd treated， administered to mice daily for 5 days at 100 mg/kg， i.p.） and group of TP per se were used. Erythrocyte fragility， the influence on cellular biochemical components， lipid peroxidation level， morphological changes， the levels of cytosolic enzymes in serum， the extent of oxidative damage and levels of the key antioxidant enzymes in liver， and hepatic histopathology in mice were evaluated. Results： The levels of Cd（Ⅱ） in liver and blood， the activities of transaminases in serum and osmotic fragility were increased by comparison with the control， while the activities of superoxide dismutase and catalase decreased significantly in the Cd-treated group. However， treating mice with TP alleviate Cd-induced oxidative damaging effects， stabilize cell membrane， prevent the changes of hepatic histopathology. Conclusion： TP not only chelates with Cd， but also plays an antioxidant role to weaken the biotoxicity of CdCl2. TP supplementation may be favorable to avoid Cd-induced hematotoxicity and hepatotoxicity for humans.

Abstract:The effect and mechanisms of DNJ on high-fat diet-induced obese mice were investigated， aiming to provide theoretical basis for the development of health food. Obesity model of mice were established by high fat diet， then all mice were treated with DNJ by oral gavage at different doses for 40 d. Then， the serum- and liver-related indicators were determined. Compared with the high-fat control group， 8.0 mg/kg bw/d of DNJ treatment significantly reduced the weight， abdominal fat factor， content of liver fat， and the levels of total cholesterol （TC）， triglyceride （TG）， low density lipoprotein cholesterol （LDL-C） and free fatty acid （FFA）， visfatin （P＜0.05）. 8.0 mg/kg bw/d of DNJ treatment also significantly increased content of high density liptein cholesterol （HDL-C）， adiponectin （ADP） （P＜0.05）， reduced the activity of enzymes involved in promote fat synthesis fatty acid synthetasein （FAS） and acetyl Coa carboxylasec （ACC）， and significantly increased activity of enzymes in decomposition related Acyl-CoA oxidase （ACO） and carnitine palmitoyl transferase-1 （CPT-1） （P＜0.05）. Conclusion： DNJ could regulate lipid metabolism in obese mice by inhibiting fat synthesis and promote its decomposition through controlling the secretion of adipokine and the activity of enzyme related with lipid metabolism.

Abstract:This experiment studied the recovery of Streptococcus lactis L16 on mice intestinal flora of Staphylococcus aureus after infection. The 16S rRNA gene sequencing library of mouse intestinal microbiota was constructed by high throughput sequencing technique， the composition and biodiversity of the prevention group， the treatment group， the control group and the model group were analyzed， by the bacterial community structures， rank-abundance distribution curves， heatmaps， rarefaction curve， Venn diagrams. Results： In the model group， the deferribacteres （12.67%） was significantly increased and the flora structure was abnormal. The relative abundance of the main phyla of firmicutes（49.03%） and the bacteroidetes （43.15%） in the prevention group was close to the control group （44.75%， 42.08%）. Conclusion： Streptococcus lactis L16 prevents intestinal infection of Staphylococcus aureus in mice and regulates the structure of intestinal flora.

Abstract:The newly harvested rice has poor sensory quality which can be improved by natural aging （3-6 months）. However， physical methods could accelerate rice aging while save aging time and reduce storage costs. In this study， rice was treated by microwave （540 W treatment for 30-50 seconds）， and subsequently the changes of gelatinization， texture and tissue structure were analyzed. After microwave treatment， a significant increase in final viscosity and setback was found. Meanwhile， the hardness of cooked rice was increased and the adhesiveness was decreased. These results indicated that microwave treatment could accelerate rice aging. Tissue structure analysis showed that after microwave treatment， disulfide bond of rice protein was increased， while an increase in intracellular cleavage and decrease in intercellular cleavage was noticed by observing the transverse section of rice grain， which indicated that microwave treatment reduced the mechanical strength of endosperm cell wall. The content of free fatty acids in rice was decreased after microwave treatment， which was different from the trends of increasing in content of free fatty acids during natural aging process， thus reducing the off-flavor of rice. In conclusion， appropriate microwave treatment accelerated the rice aging and reduced the off-flavor of rice. Microwave treated rice aging was related to the changes of endosperm cell wall and disulfide bond.

Abstract:Objective： The microcapsules of synbiotic Lactobacillus casei/ lactitol were prepared by enzymatic method. The effect of lactitol concentration on the microcapsules characteristic was studied， and the application of the microcapsules was assessed. Method： Synbiotic L. casei/ lactitol was microencapsulated in casein using internal emulsion technique with Zea mays transglutaminase （TGZ） induced gelation and alginate coating. The particle size of microcapsules and the survivability of L. casei in casein beads coated with alginate in simulated gastrointestinal conditions were studied to determine the amount of lactitol. Moreover， the morphology of microcapsules was observed by scanning electron microscope （SEM）. Finally， prepared microcapsules were added into orange juice to evaluate the survival of L. casei in low temperature storage. Result： TGZ could used as an enzyme to cross-link casein to encapsulated L. casei/lactitol. The small particle size and high encapsulation efficiency （61.73%） achieved with the addition of 1.0 g/100 mL lactitol. In simulated gastrointestinal tests， the survivability of L. casei was improved by 1.0 g/100 mL lactitol. Result from SEM observations showed complete encapsulation of probiotic cells in the wall materials， suggesting that the protection was provided by the strong penetration-resistant physical barriers of the microcapsules. The storage experiment indicated that the number of cells with lactitol were higher than those of without lactitol by 0.56 logarithmic number. Conclusion： The double-layer microcapsule has a very good protective effect on the survival of Lactobacillus， and the existence of lactitol can also improve the survival rate of probiotics， so probiotics/ lactitol synbiotics microcapsules have a broad application in food， especially in functional food.

Abstract:NFC （Not from concentration） juice is caught widely attention at present because of its rich nutrition. ‘Ralls’ apples were used as the raw materials to produce NFC cloudy apple juice in this study. The primary production process includes pulping， enzyme hydrolysis， filtration and sterilization， with the purpose of discussion the effects of process on fruit juice nutritional qualities. The research results showed that， the contents of soluble sugar and reducing sugar were increased as a whole. The contents of soluble protein， and pectin were decreased gradually during processing. The contents of soluble solids， polyphenols and flavonoids increased firstly， and then decreased. The changes of several nutritional indexes were significantly correlated during processing. Soluble protein and soluble pectin were significantly affected by the enzymatic hydrolysis process. Filtration had a greater impact on the contents of protein， pectin and flavonoids， which were the particle components in juice. Total phenols， flavonoids and other bioactive substances were significantly reduced after the sterilization process. This research could provide some theoretical reference on keeping nutrients of NFC cloudy apple juice during processing and lay a theoretical foundation for the application of processing technique on ‘Ralls’ apple.

Abstract:Grains stillage， rich in cellulose and hemicellulose， is a favorable resource of raw materials for the preparation of microcrystalline cellulose （MCC）. In order to make full use of the cellulose components in grains stillage， the preparation parameters of high purity MCC from grains distillers （GSMCC） were investigated based on acid hydrolysis method， followed by the extraction of crude fibers by nitric acid-ethanol method， and the structural characterization during isolation of GSMCC were determined. The technological parameters， such as hydrochloric acid concentration， temperature， liquid-solid ratio and hydrolysis time， were optimized by response surface method with the index of purity and yield. The results showed that the optimal preparation conditions of GSMCC were as follows： time of 2 h， temperature of 72.3 ℃， hydrochloric acid mass fraction of 7.5% and liquid-solid ratio of 25 ∶ 1（mL/g）. Under the optimal conditions， the yield， purity and degree of polymerization （DP） were 89.25%， 92.57% and 276.39， respectively. The purity of GSMCC was increased to 93.31% after bleaching， and the degree of polymerization was reduced to 255.86. The results of structure characterization by using SEM， FTIR and XRD showed that the microstructure of GSMCC is irregular granular type， which has a typical functional group of cellulose with characteristics of cellulose Ⅰ crystal. The degree of crystallinity is 67.49%. TGA shows that the heat stability of GSMCC is nice， indicating that the preparation of food additive microcrystalline cellulose from grains stillage is feasible.

Abstract:In order to investigate the influence of Monascus purpureus and Saccharomyces cerevisiae co-fermentation on the flavor of sweet red yeast rice wine， the two different strains in various proportions were combined and used for rice wine fermentation. The dynamic changes of microorganisms， organic acids and volatile aroma components were monitored during fermentation， aiming to reveal the causal relation between microbial fermentation and flavor compounds production. Microbial count showed that yeast increased in the early 12 h and then began to decrease， and Monascus correspondingly decreased in the beginning and then increased gradually during fermentation. But addition of Monascus obviously promoted yeast proliferation. Moreover， the alcohol content increased slowly as sugars were consumed during fermentation， and more organic acids were produced after 36 h of fermentation， which were mainly composed of lactic acid， acetic acid， citric acid， and tartaric acid. Remarkably， higher inoculum size of Monascus used in fermentation resulted in more sugar consumption and more alcohol and organic acids production in rice wine. Furthermore， 47 volatile components in total were detected during fermentation， including 6 alcohols， 14 acids， 12 esters， 8 ethers， 4 aldoketones， 2 quinones， and 1 phenol， in which higher alcohols （2-phenylethanol， vanillyl alcohol， isobutanol） and esters accounted for the highest content. The relative contents of acids decrease constantly， while the relative contents of alcohols， esters， and ethers increased during fermentation. Besides， addition of Monascus prominently led to a rapid increase in esters production in early fermentation and a final higher concentration of esters. To sum up， addition of Monascus in rice wine fermentation promoted the proliferation of yeast and the generation and enrichment of diverse organic acids and volatile components， especially the esters. Co-fermentation of M. purpureus and S. cerevisiae significantly contributed to the abundant flavor compounds in sweet red yeast rice wine.

Abstract:This study aimed to explore the dynamic changes of color and pigments content of the Huangjinya fresh tea leaves during processing， with a view to providing theoretical guidance for the processing and production of the fresh tea leaves of Huangjinya as well as this kind of albino tea cultivars. Taking Jiukeng， a conventional tea cultivar， as control， the changes of appearance color and intrinsic pigments contents of Huangjinya during thermal processing were analyzed and the pigments content was determined by UPLC method. Results showed that the appearance color transformed from yellow to green and the value of chromatism a* changed from positive （red） to negative （green） after fixing of Huangjinya fresh tea leaves， since the content of yellow pigments represented by lutein decreased significantly， which resulting in a significant increase in the relative content of green pigments. However， the piling process was able to make the appearance color of tea return to yellow due to the significant improvement in the relative content of yellow pigments caused by the reduction of chlorophyll a/b content. Thus， the appearance color and pigments content of tea products after piling were more similar to those of fresh leaves， so that the color advantage of fresh leaves of Huangjinya cultivars can be fully highlighted.

Abstract:By analyzing the interaction effect between SiO32- and the main taste sensation， the internal mechanism of SiO32- affecting the taste quality of tea soup was explored. The study showed that with the increase of SiO32- mass concentration， the sweetness intensity of tea soup increases， the intensity of umami， bitterness and astringency decreases， and the overall taste quality of tea soup decreases. The decreased content of catechins， tea polyphenols， amino acids， epigallocatechin gallate （EGCG） and Ca2+， K+， Mg2+ plasma leach in tea soup is the reason why SiO32- leads to the decrease of taste quality of tea soup. The results showed that SiO32- could enhance the taste of sodium glutamate solution and sweet taste of sucrose solution， and weaken the bitter taste of caffeine solution and the bitter and astringent taste of EGCG solution， with obvious taste interaction effect. It is recommended that water containing SiO32- （＜48 mg/L） should be used for daily brewing of black tea.

Abstract:The flavor stability of green tea beverages has always been a technical problem that restricts the rapid development of high-quality green tea beverages. In order to improve the flavor stability of green tea beverages， the study investigated the change of sensory quality and physical and chemical components of green tea beverages with different sucrose additions （0， 1%， 2%， 4% and 8%） during sterilization （135 ℃， 15 s） and storage （4， 25， 38 ℃； 0~60 d） during green tea processing. The results showed that the addition of sucrose during green tea processing made the taste of green tea beverages more fresh， sweet mellow and the concentration of aroma increased compared to the control. After sterilization， compared to control （no sucrose treatment）， the aroma and taste quality of the green tea beverages were improved after adding sucrose； the concentration of epicatechins increased and non-epicatechins decreased. Compared to the control， the flavor quality of green tea beverages significantly improved during storage. The brightness of the infusion color increased， the quality of aroma and taste were enhanced and concentration of tea polyphenols， amino acids， caffeine as well as catechins increased. It was available that adding sucrose within 42 days after storage can obviously increase the stability of the flavor quality of green tea beverages， and the addition of 2% and 4% sucrose could better improve the flavor quality of green tea beverages. The study showed that adding sucrose can better improve the flavor quality of green tea beverages meanwhile preserve their stability during certain storage conditions.

Abstract:Cordyceps militaris， as a novel food， is rich in water-soluble novel carotenoids. The aim of this study is to screen a safe solvent for extracting novel carotenoids from C. militaris fruiting bodies and a method of cell breakage without environmental pollution. The main purpose of this study is to obtain the optimum extraction conditions of C. militaris novel carotenoids. With the yield of carotenoids as the index， seven different solvents were used to extract carotenoids from C. militaris fruiting bodies， and the ethanol solution was determined as the optimum extraction solvent. Carotenoids were extracted by ultrasonic fragmentation method and thermal-acid method respectively， and it was confirmed that the ultrasonic fragmentation method was more conducive to the extraction of carotenoids than the thermal-acid method. Based on the single factor experiment， ethanol concentration， extraction time， and extraction temperature were taken as independent variables. The Box-Behnken design was used to establish the regression model. The optimum extraction coniditions of C. militaris novel carotenoids were obtained as follows： ethanol volume fraction of 73.4%， extraction time of 30.4 min， and extraction temperature of 54.4 ℃. Under optimal conditions， the predicted yield of carotenoids was 2 969.23 μg/g， and the experimental yield of carotenoids was 3 017.31 μg/g. There was no significant difference between the RSM-predicted yield and the experimental yield of carotenoids， and the regression model was well fitted.

Abstract:Objective： A fungal with high activity of chitosanase was isolated from soil samples and named as M7a. Then， optimize solid fermentation conditions of the strain M7a for chitosanase production. Method： The strain M7a was identified based on its morphological characters and 18S rDNA sequence. The single factor and response surface test were used to determine it’s optimum solid fermentation conditions for chitosanase production. Result： The strain M7a was identified as Purpureocillium lilacinum. The optimum solid fermentation conditions were confirmed as follows： 10 g/L colloidal chitosan + 5 g/L glucose， 10 g/L peptone， the mass ratio of soybean meal was 7 ∶ 5， the initial pH of the medium was 6.0， 33 ℃ for 5.5 d. The final chitosanase activity reached 16.80 U/mL， which was 5.1 folds higher than the beginning after optimization. SDS-PAGE and zymography analysis showed that the strain M7a secreted a 40 ku chitosanase without isozyme. Conclusion： This study screened and identified a novel strain of Purpureocillium lilacinum M7a with high chitosanase activity， and greatly improved the chitosanase production level of solid fermentation. The results can provide a theoretical basis for purification and application of the chitosanase from Purpureocillium lilacinum.

Abstract:Natural astaxanthin has outstanding biological activity and high economic value. However， many studies are still limited to the astaxanthin extraction with organic solvents such as acetone， which causes great pressure on the environment， and reduces the production safety. To explore an efficient and green process for astaxanthin extraction， novel ionic liquid （IL）-based aqueous biphasic systems （ABSs） were constructed. The effects of IL， temperature， pH on the phase behavior of the ABSs and astaxanthin distribution were investigated. The results showed that tributyloctylphosphonium bromide （[P4448]Br）， tributyloctylphosphonium chlorine （[P4448]Cl）， tetrabutylphosphonium bromide （[P4444]Br）， tetrabutylphosphonium chloride [P4444]Cl， tetrabutylphosphonium trifluoroacetate （[P4444]CF3COO）， and tetrabutylammonium bromide （[N4444]Br） could form low critical solution temperature （LCST）-type ABSs with K2HPO4/KH2PO4. [P4448]Br has the strongest ability to form ABS and the [P4448]Br-based ABS showed the highest extraction yield of astaxanthin. When the ultrasonic power of 75 W and ultrasonic time of 60 min， the extraction yield of astaxanthin in obtained from Haematococcus pluvialis by [P4448]Br-K2HPO4/KH2PO4 ABS was 96.09%. The results help us to understand the correlation between the phase behavior of the ABS and the extraction of biomolecule， and provide an important theoretical basis for the astaxanthin extraction from bioresources.

Abstract:Stinky mandarin fish was fermented at low temperature （8 ℃） with mandarin fish as raw material. The dependences of texture， color and volatile compounds in stinky mandarin fish during fermentation were studied. The results showed that the color， texture and volatile compounds of mandarin fish exhibited reasonable changes during fermentation. The lightness of fish increased first and then decreased slightly throughout the whole fermentation； both a* and b* showed a gradual decline trend. The comprehensive change of color index made the fish white and bright after fermentation. The trend of hardness， cohesiveness， gumminess， chewiness and resilience were all decreased first and then increased； adhesiveness was increased significantly at the beginning of the fermentation and then stabilized， but springing was increased gradually. The hardness of smelly mandarin fish was slightly lower than that of the fresh mandarin fish， others were increased. The composition and content of volatile compounds were gradually increasing. The fermented mature fish contained many kinds of aromatic components such as linalool， limonene， alpha-terpineol and 4-methyl-2-pentanone more components et al.

Abstract:The effect of ultrasonic pretreatment on drying properties of lemon slices was studied， with the dry base moisture content， drying rate， rehydration rate and vitamin C content as the main indicators. Results showed that the drying rate of hot-air drying lemon slices increased， the drying time decreased by at least 20% and the energy consumption of hot air drying stage significantly reduced after ultrasonic pretreatment. The shorter the probe ultrasonic pretreatment time within the experimental range， the higher the drying rate. However， the longer the ultrasonic cleaning pretreatment time within a certain range， the higher the drying rate. Ultrasonic pretreatment not only reduced the loss of vitamin C during hot air drying of lemon slices， but also improved the rehydration rate of dried products. The longer the time of probe ultrasonic pretreatment， the greater the loss of vitamin C， and the lower the rehydration ratio， so the pretreatment time should be shortened in the application. With the increase of ultrasonic cleaning pretreatment time， content of vitamin C in dried lemon slices decreased gently and the rehydration ratio gradually increased， while there was no significant change after the ultrasonic pretreatment time increased to 11 min （P<0.05）. The content of vitamin C in dried lemon slices pretreated with probe ultrasound for 3 min and dried by hot air for 160 min was 32.93 mg/100 g and the rehydration ratio was 4.61 ± 0.08. Moreover， the content of vitamin C in dried lemon slices pretreated with ultrasound cleaning for 11 min and hot-air drying for 160 min was 29.70 mg/100 g and the rehydration ratio was 4.60 ± 0.13.

Abstract:The growth of Salmonella in food is a major threat to public health. The objective of this study was to develop growth prediction models of Salmonella in tuna sashimi under static and dynamic conditions. The growth of Salmonella in tuna sashimi was investigated under constant temperature conditions （8-35 ℃） to evaluate the effect of temperature on growth rates and lag times. Duplicated experiments were conducted， and the data set from one replicate was used to directly construct both primary model （Huang model and Baranyi model） and secondary model （Huang Square-Root model， HSR） through one-step kinetic analysis. The Fourth order Runge-Kutta method and nonlinear least square method were combined to searching the parameters of the models. The data set from the other replicate under constant temperatures and newly designed dynamic temperature conditions were chosen for model validation. The results showed that one-step approach can be used to analyze the growth curves of Salmonella in tuna sashimi. Though both Huang-HSR models and Baranyi-HSR models had an equal goodness of fit， the former was the recommended model in this study， because of the explicit form of definition for the lag phase in Huang model. The minimum growth temperature of Salmonella was 6.91 ℃， and the maximum cell density of Salmonella was 9.15 lg（CFU/g）. The root-mean-square errors （RMSE） of validation at isothermal condition and dynamic condition were only 0.37 lg（CFU/g） and 0.44 lg（CFU/g）， with the residual errors of predictions following Normal distribution and Laplace distribution， respectively. This study showed that one-step kinetic analysis is a useful and efficient method to directly construct primary and secondary growth models. The models developed in this study can be used to predict the growth of Salmonella in tuna sashimi and conduct risk assessment.

Abstract:Fresh common bean is an important vegetable to supplement plant protein. However， postharvest senescence and lignification seriously lead to the loss of consumer acceptance and eating quality of fresh common bean. To understand the effect of 1-MCP on postharvest lignocellulose of fresh common bean. The effects of 1-MCP on physiology， cellulose， lignin and related enzymes of fresh common bean cv. Baibangdou， Wujinbaibangdou and Qingbangdou were investigated. The results showed that the effects of 1-MCP on postharvest lignocellulose of different varieties of P. vulgaris L. were different. 1-MCP treatment inhibited the conversion of reducing sugar to cellulose by reducing the activities of sucrose phosphate synthase （SPS） and sucrose synthase（SuSy）. 1-MCP treatment reduced the synthesis of lignin monomers by inhibiting the activities of phenylalanine ammonia lyase （PAL）， 4-coumarate： coenzyme A ligase （4CL）， cinnamyl-alcohol dehydrogenase （CAD）， and inhibited the polymerization of lignin monomers by suppressing the peroxidase （POD） activity and the conversion of O2·- to H2O2， and ultimately inhibiting the lignin fibrosis of fresh common bean.

Abstract:Objective： Heterocyclic aromatic amines， represented by PhIP were carcinogens that could be often formed in meat products. Black peppers， a commonly used spice in meat processing industry， which was proved to affect the formation of PhIP， with significant differences in its effect. Therefore， it is important to explicit the key compounds that affect the inhibitory of PhIP formation in the black pepper. Method： In this study， the extract solvents for black pepper extraction were decided by comparing the PhIP inhibitory efficiency of different extracts， before preparing a group of certain extract. Then the compound peaks in HPLC spectrograms represented the key compounds that affect the PhIP inhibitory efficiency were screened and identified by principle component analysis （PCA）. Results： Compared to other extracts， the ethanol extracts in black pepper have the highest PhIP inhibitory activities. And the top PhIP inhibitory efficiency was achieved when the extract extracted by 100% ethanol under ultrasonic for 60 min were added. Two key peaks in HPLC spectrograms were screened using PCA， modeling the peak area from 24 ethanol extract prepared by different extract conditions and the PhIP inhibitory efficiencies. The key compounds peaks were finally identified as eugenol and quercetin by using HPLC-TOF-MS. Conclusion： The ethanol extracts from black pepper were a kind of good PhIP inhibitor of meat products， in which the core compounds that mostly affect the inhibitory activities were eugenol and quercetin. The results obtained in this research could offer fundamental basis for the proper usage of the black pepper which were proved to be a nature PhIP inhibitor.

Abstract:The chlorogenic acid reference material was prepared using honeysuckle as raw material by the method of water extraction and ethanol precipitation combined with medium pressure preparative liquid chromatography and further analyzed and identified. Firstly， the identification on chemical structure of the obtained reference material was carried out by FT-IR spectroscopy， UV spectroscopy， MS， NMR H and C spectra. Furthermore， the homogeneity （inter- and intra-bottle difference） and short-term （one week， room temperature， 4 ℃， -20 ℃） and long-term （six months， -20 ℃） stability of the obtained standard reference material were evaluated using HPLC with UV detector. Finally， the multi-lab joint determination method was used to certificate the reference substance and the uncertainty of the certification results was evaluated. The obtained experimental results show that the purity value of the prepared chlorogenic acid is above 99%， and the effective period is at least 6 months （-20 ℃）. This reference chlorogenic acid has high purity， good homogeneity and stability， and can be used for confirming and evaluating the analysis method of chlorogenic acid in the honeysuckle.

Abstract:In order to evaluate the effect of heavy metal artificial antigen， heterocyclic bifunctional chelators（BFCs），2-S-（4-Aminobenzyl）-1，4，7-triazacyclononane-1，4，7-triacetic acid（P-NH2-Bn-NOTA）and heavy metal Pb2+ were selected. The Pb2+ was conjugated to bovine serum albumin （BSA） and ovalbumin （OVA） with glutaraldehyde method to produce the artificial antigen based on the bifunctional chelators NOTA， respectively. The conjugation ratio was 9 and 7 for the Pb2+-NOTA-BSA conjugate and the Pb2+-NOTA-OVA conjugate， respectively. The polyclonal antibody （PcAb） was obtained after immune rabbits. Based on the PcAb， an indirect ELISA was established and its linear regression equation was y=12.127ln（x）-11.386 （R2=0.9961）. According to the ELISA， the value of detection limit （IC20） and IC50 were 13.30 and 157.89 ng/mL， respectively. The specificity analysis showed that the cross-reactivities（CR） were all less 5.3% except Cd2+ was 12.3%， which indicated that the PcAb was specific for Pb2+. The produced Pb2+ artificial antigen and the PcAb could lay the foundation for rapid analysis of heavy metal residue using the BFCs.

Abstract:Based on near-infrared spectroscopy and chemometrics methods， a non-destructive classification method for different brands and counterfeit soybean milk powder was established in this paper. A total of 132 spectra of counterfeit， domestic and foreign brands were collected. Continuous wavelet transform method was used for the elimination of background and baseline interference. Characteristic wavelengths selection was achieved based on the standard deviation and relative standard deviation. Then principal component analysis method was applied to analyze the spectra of different brands and counterfeit samples. The results show that the baseline interference was effectively eliminated by the continuous wavelet transform method， and discrimination ability was greatly improved by the wavelength screening method. The classification accuracy among counterfeit， domestic and foreign brands is 100%， and the classification accuracy of different brands samples is 93.94%. The results show the classification of counterfeit and different brands of soybean milk powder samples can be achieved by the proposed method， which provides a new idea for the rapid and non-destructive analysis of soybean milk powder samples.

Abstract:Objective： This study describes preparing genomic DNA samples of foodborne pathogens which meet the requirements of national nucleic acid reference materials with independent intellectual property rights by using the domestic bacterial genomic DNA extraction kit. Methods： Four foodborne pathogens， Escherichia coli O157：H7， Listeria monocytogenes， Salmonella enteritidis and Staphylococcus aureus were used in this study. The imported OMEGA bacterial genomic DNA extraction kit and the domestic TIANGEN bacterial genomic DNA extraction kit were used to extract the genomic DNAs of the four pathogens. And the genomic DNA extraction methods of E. coli O157：H7， S. enteritidis and S. aureus with low concentration and purity extracted from domestic TIANGEN kit were optimized. Finally， the integrity and purity of the genomic DNAs of the four pathogens were detected by agarose gel electrophoresis， and the characteristic virulence genes of the four pathogens were verified by PCR amplification. Results： The genomic DNAs’ mass concentrations of the four pathogens extracted by the domestic TIANGEN bacterial genomic DNA extraction kit were greater than or equal to 50 ng/μL， and the values of A260/A280 and A260/A230 were between 1.7-2.0. The bands of the genomic DNAs are clear， free of RNA and protein contamination， and the characteristic virulence genes of each strain are positive. Conclusion： Through the optimization of genomic DNA extraction method， four pathogen genomic samples conforming to the requirements of national nucleic acid standard materials were obtained， which laid a foundation for the subsequent preparation of large quantities of nucleic acid standard samples.

Abstract:Pyrethroid accumulation in body will cause harm to human nerves and skin， and even mutation， resulting in birth defects and cancer. λ-Cyhalothrin is a typical pyrethroid insecticide， and the residue in food has attracted widespread public attention. An analytical method was established for the determination of λ-cyhalothrin residues in tea by high performance liquid chromatography. The chromatographic conditions was chosen Inertsil ODS-C18（150 mm × 4.6 mm， 4.6 μm）， chromatographic column using water （1% formic acid） -methanol （15 ∶ 85， V/V） as mobile phases， detection wavelength was 210 nm and velocity was 0.5 mL/min. The optimum ultrasonic conditions are as follows： the ratio of material to liquid is 1 ∶ 10 （g/mL）， the ultrasonic power is 80 kHz， the ultrasonic time is 40 min， and the ultrasonic temperature is 20 ℃. The results showed that the linear range of λ-cyhalothrin was 1~100 μg/L and the correlation coefficient was 0.9998. The average recoveries ranged from 76% to 103% with relative standard deviation less than 3.853%， the LOD and LOQ were 0.2 μg/L and 1 μg/L， respectively.

Abstract:Chickpeas（Cicer arietinum L） are highly nutritious legumes， in order to better understand its nutritional value， phenolics were extracted with 80% methanol solution， the content and antioxidant activity of phenolic compounds in different existing forms in the extract were determined， and analyze on qualitative， quantitative of 80% methanol solution. The results showed that the contents of total phenols and antioxidant activity in different forms of chickpeas were different， the phenolic content of glycoside phenolic compounds was the highest （0.81 mg/g）， the content of free phenolic flavonoids was the highest （0.26 mg/g）. The 80% methanol extracts were separated by UPLC-QTOF-MS， and identify 24 compounds including 4 phenolic acids and 12 flavonoids. Quantitative analysis by HPLC-QQQ-MS showed that p-hydroxybenzoic acid， coumalic acid and protocatechuic acid compounds are rich in chickpeas.

Abstract:The smoked horse sausage is a traditional meat product which is popular among Kazakhs， and both the cooked smoked horse sausage and mature liquid are well welcomed. In order to quantify the taste and flavor change of the smoked horse sausage during cooking， the main flavor， free amino acids， taste characteristics and volatile flavor substances of samples sampled at different cooking time were analyzed. Results showed that the total amount of free amino acids in soup presented an increasing trend， the total free amino acids of products cooked for 105 min and 120 min were significantly higher than that of the initial sample （P<0.05）. The influences of cooking time on the proportion of umami taste amino acid， sweet taste amino acid and bitter taste amino acid was not significant （P>0.05）. The saltiness value， umami value， richness， bitterness value and bitter aftertaste value of the soup showed an increasing trend with the prolongation of cooking time， while the astringency value and the astringency aftertaste value showed no obvious change. The volatile components of the soup were significantly different in different cooking times， the total amount of volatile substances showed a trend of decreasing after increasing. The variance contribution rate of the main flavor components of the soup on PC1 and PC2 was 97.06%， each product had its own flavor characteristics， and the variance contribution rate on LD1 and LD2 was 85.27%， which mean the different samples could be effectively distinguished by principal component analysis. The content of free amino acid was higher when cooked for 105 min， the main flavor was maintained to some extent， and the degree of astringency was not significantly increased. Suitable processing parameter was obtained after cooking for 105 min， the results provide reference for cooking， processing and consumption of smoked horse sausage， as well as for further research on the flavor and taste of smoked horse sausage.

Abstract:The volatile compounds of Jiaozi steamed bread （JSB） and yeast steamed bread （YSB） were collected by simultaneous distillation and extraction （SDE） and headspace solid phase microextraction （HS-SPME）. The volatile compounds and aroma characteristics were analyzed by GC-MS and GC-O. The results showed that SDE absorbent was suitable for fractionation and concentration； the optimum conditions for HS-SPME： adsorption temperature was 55 ℃， adsorption time was 30 min and desorption time was 6 min. GC-MS analysis showed that there were 23 components in the two kinds of steamed breads. The main components were ethanol， 3-methyl-1-butanol， n-hexanol， 2-pentyl-furan， （E）-2-nonylaldehyde， 2-pentylfuran， naphthalene， benzaldehyde， amylbenzene， nonanal and geranyl acetone. The relative content of the common components in JSB was higher （>60%） than that in YSB （<50%）， and the relative content of ethanol in JSB was the highest （63%）. The relative contents of acids， benzenes and heterocyclic compounds in JSB were higher than those in YSB， showing mellow， fruity and nutty flavor. However， alkenes， aldehydes， esters and ketones in YSB are higher than those in JSB， and their aroma is not as strong as JSB. There are obvious differences in the types and relative contents of volatile substances between JSB and YSB， which lead to their different aroma characteristics.

Abstract:High Fischer ratio oligopeptides are small peptide systems with a low aromatic amino acid and highly branched-chain amino acids. Due to its unique amino acid composition， high Fischer ratio oligopeptides have their unique physiological functions. This review summarized the current status of production of high Fischer ratio oligopeptides and their mechanism of enzymatic production. The present problems existing in production of high Fischer ratio oligopeptides are discussed， and the mechanism of how to achieve efficient enzymatic hydrolysis of producing high Fischer ratio oligopeptides based on endopeptidase and exopeptidase system are also discussed.

Abstract:Due to the unique chemical structure， saponins have shown many physiological effects such as anti-tumor， anti-inflammatory， immune regulation， antiviral， liver protection， et al.， and have been widely used in the field of food and medicine. Meanwhile， as everyone knows that protein is an important part of various food systems. The interaction between saponin and protein can change the structure and function of protein， and then affects the quality of food， which has aroused widespread concern in academic circles. In this paper， the mechanism， influencing factors， and analysis methods of the interaction， as while as the effects of the interaction on protein structure and functional properties are reviewed in order to provide a theoretical basis for the influence of saponin and protein interaction in complex food systems.

Abstract:The food-borne oligopeptides （generally 2-10 amino acids）， derived from edible protein， can be absorbed without digestion or a little digestion. In additional， the food-borne oligopeptides with less than 1 000 u have various physiological functions including antioxidative effect， antimicrobial effect and anti-angiotensin converting enzyme activities， and in recent years， they have been widely used in food， health care products and cosmetics industries. However， at least 5 amino acids are required to form epitopes， and food-borne oligopeptides may theoretically present a potential risk of IgE-mediated allergy by forming epitopes. Accordingly， this paper analyzed the factors that may cause the allergenic risks of food-borne oligopeptides， such as the presence of antigenic epitopes and possible cross-allergic reactions， and reviewed the methods that may be used to evaluate the sensitization of food-borne oligopeptides， finally， this paper discussed how to reduce the allergenic risks of food-borne oligopeptides. This will provide a theoretical basis for the wider application of food-borne oligopeptides.