Abstract:The probiotics industry is vigorous, and fermented dairy products, as an important carrier of probiotics, are constantly upgraded. With the deep research on intestinal flora, new understandings on human nutrition and health regulation addressed. Therefore, it has become a consensus that the use of healthy diet such as probiotics fermented dairy products to regulate intestinal health and thus prevent and treat chronic diseases of the human. This paper reviews the research progress and industrialization status of probiotics fermented dairy products in recent years, and emphasize on the function of probiotics fermented dairy products in intestinal diseases, tumors and intestinal-X axis, which is expected to provide a theoretical basis for the research and development of probiotics fermented dairy products.
Abstract:Low-dosage glycerol monolaurate (GML) administration was able to induce dyslipidemia and low grade inflammation in mice. Lactobacillus plantarum ZJUFT34 (T34) was used to regulate the serum lipids, insulin and cytokines in overweight mice induced by GML, in order to address potential health risks associated with GML consumption. Male C57BL/6 mice were divided into two groups, fed with basic diet and basic diet containing 150 mg/kg GML, respectively. T34 was administered to mice after they exhibited significant body weight gain induced by GML. Blood samples were collected after a three-week T34 treatment. The levels of lipids, fasting glucose, insulin and cytokines in serum were determined. The results showed that the administration of T34 could maintain the significant body weight gain of the mice induced by GML and the final body weight was 2.48 g (approximately 9.3%) higher than the control group. T34 in combination with GML significantly elevated the ratio of high-density lipoprotein-cholesterol to low-density lipoprotein-cholesterol (HDL-C / LDL-C), ameliorated insulin resistance, decreased the pro-inflammatory cytokine interleukin-6 (IL-6) level, and upregulated the anti-inflammatory cytokine transforming growth factor-β (TGF-β) level. T34 in combination with GML not only exert the beneficial effects of GML to promote mice growth, but also reduce the potential harm of GML and maintain health of mice.
Abstract:Objective: To investigate the protective effects and mechanism of Zhenjiang aromatic vinegar (ZAV) on nonalcoholic fatty liver disease (NAFLD) in mice. Methods: The model mice were made by feeding with high fat diet for eight weeks, and ZAV were given by intragastric administration at the same time, once a day. Eight weeks later, the levels of serum glucose, lipid and free fatty acid, the activities of antioxidant enzymes and the content of malondialdehyde in the liver were measured. The levels of serum insulin and inflammatory cytokines were measured by ELISA. The histopathological changes of hepatic tissue were observed by hematoxylin and eosin staining. Results: Compared with the model group, ZAV significantly reduced body weight and fat weight, significantly reduced the levels of triglyceride, free fatty acids, glucose and insulin in serum, increased antioxidant capacity and reduced the levels of inflammatory factors in mice. The hepatic tissue histopathological changes of ZAV treated groups were significantly improved. Conclusion: ZAV had obvious protective effects on NAFLD in mice, which perhaps related to its effects of regulating serum lipids and reducing insulin resistance and oxidative stress and inflammatory reaction.
Abstract:Probiotic character and safety assessment of 20 lactic acid bacteria isolated from Shanxi aged vinegar was investigated in the present work. The results showed that L. plantarum 172, 173 and L. fermenti 179 were potential probiotics with strong ability of DPPH scavenging, cholesterol removal, biogenic amine degradation and ACE-I activity. Also, the higher producing property of bacteriocin, GABA and acetoin were observed in the three strains. The virulence genes PCR results showed that most of the strains were negative, with only a few strains showing hyl (2/20) and ace (2/20) positive. The most detected antimicrobial resistance genes were ermB (70%, 14/20) and tetM (65%, 13/20). blaZ and vanX were detected in two strains of L. amylovorus. Additionally, 7 strains carried tdc genes (tyrosine decarboxylase), 5 strains carried odc (ornithine decarboxilase) genes, and the hdc (histidine decarboxylase) genes were not detected in this study. All of strains were negative in the test of indole, nitrate reductase and D-lactic acid producing. The mice toxicology test furtherly demonstrated the safety of L. plantarum 172, 173 and L. fermenti 179, which provided a scientific basis for future research and application.
Abstract:Objective: This article was designed to study the antioxidant activities of two kinds of stevia residue extracts on D-galactose(D-gal) induced aging mice. Methods: Eighty mice were randomly divided into control group, D-gal group, low, medium and high dose of two kinds of stevia residue extracts(100, 200, 500 mg/kg bw) groups. The aging model was established by subcutaneous injection with D-gal(500 mg/kg bw), and the mice in the control group were injected subcutaneously with the same volume of normal saline. The mice in the sample groups were given different doses of stevia residue extracts by gavage. After 11 weeks, the activity of superoxide dismutase (SOD), glutathione peroxidase (GPx), and the content of malondialdehyde (MDA) in serum, liver and brain, and the relative expression of antioxidant enzyme gene in brain tissues were measured. Results: Compared with D-gal group, two kinds of stevia residue extracts could increase the activity of serum, liver and brain antioxidant enzymes (SOD and GPx) and decrease the content of MDA in different degree, and the effect was the most obvious at high dose (500 mg/kg bw). The relative expression of antioxidant enzyme genes (Nrf-2, SOD1, GPx1, HO-1) in brain tissue of mice in the high dose group (500 mg/kg bw) was significantly increased. Conclusion: The two kinds of stevia residue extracts can increase the activity of antioxidant enzymes and decrease the MDA level in mice by promoting the gene expression level of antioxidant enzymes and possess potential anti-aging effect.
陈琦;郭静科;许明明;俞晓卫;陈汉;刘树滔;柯李晶;周建武;饶平凡
Abstract:Free radical is a perssad with unpaired electrons. Previous studies indicated free radical levels correlate with bioelectricity, which further influence on electrophysiological signals of body surface (e.g. electrical potential difference between acupuncture meridian acupoints). The oxidation-reduction potential and antioxidative activities of lapsang tea infusion were measured and compared to those of tea polyphenols solution and tea polysaccharides solution in this study, whose content is same to its counterpart in lapsang tea infusion, respectively. The electrophysiological signals of 30 volunteers before and after drinking lapsang tea infusion, tea polyphenols solution, tea polysaccharides solution and water were measured and tracked in 90 minutes. The results indicated that the electrophysiological signals of body surface showed obvious changes within 90 minutes after drinking, but varied significantly among the results caused by drinking tea infusion, tea polyphenols and tea polysaccharides solution, respectively, which imply there were remarkable differences in antioxidative capacity, location and even mechanism among this three solutions in vivo. The determination of electrophysiological signals on body surface might be able to become a new approach for fast and direct reflection of food-human interaction, providing a new insight for the studies of food effective ingredients.
Abstract:In this study, non-small cell lung cancer A549 was used as a model to determine the mechanism by which C-phycocyanin (C-PC) regulated the biological behavior of A549 cells. MTT assay, clonal formation assay, flow cytometry and scratch assay were used to examine the effects of C-PC on cell proliferation and migration. The key gene receptor interacting protein kinase 1 (RIPK1) was screened by transcriptome sequencing analysis, the silencing efficiency was detected by real-time PCR and western blot, and the effect of cell proliferation and migration capacity in vitro was verified by transfecting RIPK1 small interfering RNA. The C-PC reduced cell survival rate, growth rate, and cell colony formation ability. After transfecting RIPK1 siRNA, the expression level of RIPK1 was inhibited. Meanwhile, cell growth rate, colony formation and migration ability were suppressed. The cell cycle exerted G1 phase arrest. This work indicated that C-PC could inhibit the proliferation and migration of A549 cells by down-regulating RIPK1 expression level, which laid a foundation for the deep utilization of new anti-cancer functional food colorants. It also provides the necessary theory for the safe treatment of non-small cell lung cancer.
Abstract:In vitro cell models were used in this study to investigate the effect of different phenolics extracts of Chinese sumac (Rhus chinensis Mill.) fruits on cellular oxidative damage and 3T3-L1 differentiation at the cellular level. The results indicated that the three different solvent extracts and free phenolic fraction of Rhus chinensis Mill. fruits had good protection effects on the H2O2 induced oxidative damage of HepG2 cells and could significantly reduce the cellular ROS and apoptosis. In addition, those phenolic fractions could also significantly inhibit the differentiation of 3T3-L1 MBX preadipocytes. Results of the present work may supply scientific basis for further application of Rhus chinensis Mill. fruits.
Abstract:Wheat protein hydrolysis rich in glutamine were obtained by two(PWGH) or three-enzymes (AWGH) combined hydrolyzed methods. Then their abilities in resisting the oxidative stress of intestinal cells (Caco-2) were studied after the digestion in vitro. The results showed that both of PWGH and AWGH could alleviate the decrease of cell survival rate, and reduce the degree of cells damage. Moreover, the hydrolysis still maintained their activities after digestion, but the digestion of wheat protein showed no effect on the cell survival rate. PWGH and AWGH both improved the cellular antioxidant capacity, with an increase of intracellular GSH and decrease of lipid oxidation of damaged cells. The PWGH still had the function after digestion, but AWGH had no effect on the cellular antioxidant capacity and the level of GSH on damaged cells after digestion. It indicated that some active fragment in AWGH might be damaged after digestion, but not for the digestion of PWGH. Besides, it is worthy to note although the digestion of wheat protein could reduce the lipid oxidation of damaged cells, it had no effect on the cellular antioxidant capacity and GSH level.
Abstract:Different concentrations of malondialdehyde were used to oxidize rice bran protein, and then the rice bran protein was heat-treated in a condition of 95 ℃ water bath to investigate the effect of heat treatment on in vitro pepsin digestibility of rice bran protein and antioxidant activity of rice bran protein hydrolysates. The results showed that as concentration of malondialdehyde increased, the content of carbonyl and disulfide bonds of rice bran protein increased, and the content of free sulfhydryl decreased, which confirmed that oxidative modification by malondialdehyde resulted in oxidation of rice bran protein. As malondialdehyde concentration increased, pepsin digestibility, initial digestion rate of rice bran protein, and content of peptides with molecular weight distribution of 500-1 500 u in the pepsin digestion products gradually deceased. In addition, free radical scavenging abilities on ABTS+·, DPPH·, ·OH, O2-·, metal chelating ability and reducing power of rice bran protein in vitro pepsin hydrolysates gradually deceased. Heat treatment could increase pepsin digestibility, initial digestion rate of rice bran protein as well as active peptide content and antioxidant activity of rice bran protein in vitro pepsin hydrolysates. The results indicated that oxidative modification by malondialdehyde lead to decease of rice bran protein digestibility and antioxidant activity of rice bran protein in vitro pepsin hydrolysates, and the moderate heat treatment could result in increase of rice bran protein digestibility and antioxidant activity of rice bran protein in vitro pepsin hydrolysates.
苏东林;李培骏;张丽萍;袁洪燕;朱玲风;谢秋涛;潘蒋娟;刘伟;朱向荣;张菊华;李高阳;单杨
Abstract:In this present study, surfactant-mediated ultrasound-assisted extraction(S-UAE) was applied to extract pectin from citrus peel. The effect of extraction pH, ultrasound time, and liquid solid ratio (LSR) on yield, galacturonic acid (GA) content, and degree of esterification (DE) of extracted pectin from the citrus peel was investigated. The highest pectin yield (but only 17.1%) was obtained under pH of 0.6, ultrasound irradiation time of 15.0 min, and LSR of 21.0 mL/g by using response surface methodology. And on this basis, synergistic actions by surfactants and ultrasound assisted extraction were studied for pectin extraction in the work. When sodium dodecyl sulfate (SDS) (8 g/L) was added to the extraction media before ultrasound irradiation, the yield of pectin increased by 55.0% (PY of 26.4% ± 0.8%) compared with control. Furthermore, the yields and physicochemical properties, e.g. GA content, DE and average molecular weight(Mw) of extracted pectin by using conventional extraction, UAE, and S-UAE were compared. So, S-UAE has been proved to be an efficient and cost-effective method for citrus peel pectin extraction. In addition, high methoxyl citrus pectin was used to produce an amidated pectin under low temperature, parameters such as reaction temperature, pH value and pectin concentration were studied. The results indicated that DA 13%-22%, DE 29%-39%, GA 69%-84%, intrinsic viscosity 136-172 mPa·s and Mw 148-173 ku of the amidated product under the optimized conditions (reaction temperature 10 ℃, pH 11.5, pectin mass concentration 20 g/L, and reaction time 100-180 min), meet the domestic and foreign standards requirements. This study provides a positive and useful reference for the high value utilization of citrus by-products in China.
Abstract:In order to study the effects of refining treatments on the apple alcohol-insoluble residue. The cloudy apple juice was treated by wet-superfine grinding and high pressure homogenization. The characteristics of AIR extracted from the cloudy apple juice were analyzed including galacturonic acid (GalA) content, degree of methoxylation (DM), weight average molar mass (Mw), number average molecular weight (Mn), neutral sugar content and structural functional groups. The results showed that the GalA content increased with the increment of homogenization cycle and inlet temperature. The DM showed an increasing trend with the increment of homogenization pressure, cycle and inlet temperature. The DM of all refined samples were greater than 60%, than was, each sample was high esterification pectin. With the increment of homogenization pressure, the Mw showed a decreasing trend, while the Mw/Mn had the same tendency except for the homogenization pressure of 30 MPa. With the increment of the homogenization cycle, the Mw/Mn showed a decreasing trend. With the increment of inlet temperature, the Mw showed an increasing trend. For the neutral sugar contents of all samples, the content of glucose was the highest, and the galactose was the secondary compound. The above results revealed that different refining treatments had effects on the structural characteristics of AIR. The results from the present study could provide theoretical basis for the subsequent production of high-nutrient juices.
Abstract:Trypsin hydrolysis is an effective method to produce functional liquid egg yolk. Pasteurization is necessary for microbiological safety in liquid egg production. This study investigated the effects of different heat treatments (60, 64, 68 ℃ and 72 ℃, 4 min) on the functional properties and thermal stability of liquid egg yolk hydrolyzed with trypsin. The results showed that functional properties of liquid egg yolk hydrolyzed with trypsin, such as emulsifying activities and emulsion stability, protein solubility, the water absorption capacity and the oil absorption capacity, foaming capacity and foam stability, were significantly higher (P < 0.05) than that of liquid egg yolk without trypsin hydrolysis. Emulsifying activities, protein solubility and foaming capacity of liquid egg yolk with/without trypsin hydrolysis showed significantly decreasing with the temperature increasing. The result of SDS-PAGE illustrated that trypsin hydrolysis could obviously change the distribution of protein molecular weight in liquid egg yolk, and higher temperature heat treatment (68 ℃ and 72 ℃) resulted in significant protein aggregation. Fourier transform infrared spectroscopy results confirmed that trypsin hydrolysis and heat treatment had a significantly effect on egg yolk -OH functional groups.
Abstract:The Lactococcus lactis K6 isolated from mussel is able to produce Nisin Z. In order to obtain the optimized conditions of Nisin Z production, a systematic optimization experiment in our study was conducted by using minimum inhibitory concentration (MIC50) as an evaluation index against Staphylococcus aureus. Initially, the effects of single factors including different culture media, initial pH of culture broth, inoculum amount, and incubation temperature and incubation period on Nisin Z were explored. Results showed that initial pH of culture broth, incubation temperature and incubation period had significant effects on the production of Nisin Z. Subsequently, response surface analysis based on the previously study on the three significant variables were used to optimize the conditions for Nisin Z production. The optimal conditions were obtained as follows: inoculum cultural amount was 0.5% (V/V), initial pH of broth was 7.5, incubation temperature was 29.8 ℃ for 9 hours. Under these conditions, the MIC50 of Nisin Z reached 0.625 BU/mL that was 8-fold increasing against S. aureus compared to the original conditions. Importantly, Nisin Z showed complete killing (bacteriocide) mechanisms against S. aureus with 8 h. The predicted values were close to the actual values, indicating the established model in this study is applicable for the massive production of Nisin Z.
Abstract:In the study, 55 strains of lactic acid bacteria which were isolated from Tibetan air-dried meat and Bameng Zhongqi beef and mutton samples were screened by lipid plate method, a strain TR1-1-3 of lipase with high lipase activity was isolated and identified as Lactobacillus helveticus by 16S rDNA molecular biology. The fermentation enzyme production conditions of the strain were optimized by Box-Behnken response surface method on the basis of single factor experiment (inoculation amount, temperature, pH value, culture time, metal ions). The results showed that the optimal solution could be obtained by Box-Behnken quadratic multivariate regression model equation, the optimum conditions were inoculation amount 2%, 36.2 ℃, pH 5.84, 48 h. Under these conditions, the enzyme activity was 10.92 U/mL, which was higher than before optimization. Moreover, the inoculum had the greatest influence on the enzyme production of the strain, followed by pH value and temperature. The interaction of the three factors was more significant, while the metal ions had less effect on it. Fe2+ and Mn2+ activated the enzyme production and Ca2+, Mg2+, Cu2+ have different degrees of inhibition.
Abstract:In this paper, Phaseolus radiates L. starch as the raw material, the Phaseolus radiates L. resistant dextrin were prepared by acid hydrolysis method, and were purified by the sequential simulated moving chromatography (SSMB). The optimized process parameters were: feed rate 455 g/h, water consumption 682 mL/h, circulation quantity 346 mL. Under these conditions, the purified Phaseolus radiates L. resistant dextrin concentration was 24.6%, the purity was 99.17%, and the yield was 91.31%. Molecular characteristics of Phaseolus radiates L. resistant dextrin were analyzed by the SEM, FTIR, XRD, SEC-MALS and GC-MS, it had high purity and excellent molecular characteristics, it could provide theoretical principle for the development and utilization of resistant dextrin.
Abstract:As a water-soluble plant polysaccharide, soy hull polysaccharide (SHP) not only has good gelling, stability and thickening properties, but also present certain probiotic function. In order to explore the application effect of SHP added in cherry jam, the influence of SHP with different molecular weight on the rheological properties of cherry jam was firstly investigated, and the commercial pectin was placed as a control group. Then, response surface method was used to optimize the concentration ratio, sweetener and amount of SHP in cherry jam, and the better jam technology and formula was obtained. The results showed that, compared to the cherry jam with commercial pectin added, the energy storage modulus of the cherry jam with high molecular weight SHP was slightly lower than that with commercial pectin, and their viscosity were similar. The cherry jam with high molecular weight SHP presented better rheological properties. Therefore, SHP with high molecular weight was more suitable to be added into the cherry jam compare with other two kinds of molecular weight. The sensory score of cherry jam was the highest when the concentration ratio of jam was 45%, xylitol 25%, and high molecular weight SHP 0.6%. This study could provide theoretical reference for expanding the application scope of SHP.
Abstract:The effects of drying temperature, slice thickness and drying time on the flavor quality of garlic flavoring were studied in order to optimize the preparation conditions of garlic flavoring powder, and high-quality garlic flavoring powder was prepared by using hot air drying method. Box-Behnken design and response surface method were used to experiment with sensory score as response value. The results of the response surface method were mutually verified by the combination of artificial neural network and genetic algorithm. The results indicated that the optimal conditions for the preparation of garlic flavoring powder were as follows: the drying temperature was 61 ℃, the drying time was 5.9 h, and the slice thickness was 2.7 mm. The sensory score of the product obtained under this condition was 18.70 points and the relative error from the model’s predicted value was 0.74%. The predicted value calculated by the GA-BP artificial neural network model was 18.5622 points. This means that the experimental value fits well with the predicted value of the model. Therefore, artificial neural network combined with genetic algorithm is a reasonable and feasible method for the preparation conditions of flavoring garlic powder.
Abstract:In order to realize the high value utilization of fish meal pressed liquor, the fermentation preparation conditions of fish juice were optimized by single factor and orthogonal experiment on the basis of enzymatic hydrolysis of fish meal pressed liquor. The quality of fish juice was analyzed by physical and chemical tests and sensory evaluation. The results showed that the optimum technology conditions were hydrolysates were fermentation at 40 ℃ for 18 d with 9 g/100 mL Qu addition amount and 18 g/100 mL salt. The prepared fish juice had strong soy-sauce flavor, fresh delicious taste and no other bad smell, which form and color were similar to the marketed fish sauce. Although the contents of amino acid nitrogen, total nitrogen and amino acid in fish juice were lower than those of marketed fish sauce, its contents of salt and biogenic amines were significantly decrease as well as with higher taurine content. The above results indicated the prepared fish juice had good nutrition and safety, and could be used as the base material of seafood seasoning, which provides a new approach to improve the comprehensive utilization by-products of fish meal processing.
Abstract:In order to develop fermented egg cheese products, the texture and flavor of fermented egg cheese were studied. On the basis of single factor experiment, the effects of the addition amount of whole egg powder, egg white powder, carrageenan, gelatin, lactic acid bacteria and fermentation time on the fermented egg cheese texture (hardness, viscosity, cohesion, elasticity, adhesiveness and chewiness) were studied through the uniform design experiment. The results showed that the optimal fermentation conditions for the texture of fermented egg cheese were: 5% of total egg powder, 5% of egg white powder, 0.5% of carrageenan, 1% of Streptococcus thermophiles and simultaneous fermentation for 3.5 h. Flavor substances of fermented egg cheese were determined under optimal texture by GC-O-MS. There were 10 kinds of pleasant flavor substances, 5 kinds of unpleasant flavor substances, 4 kinds of neutral flavor substances and pleasant flavor dominated.
Abstract:In order to improve the lack of sensory and flavor of fermented foods made by active dry yeast, this study takes Lactobacillus sanfranciscensis isolated from traditional fermented sourdough as the research object. L. sanfranciscensis strain with high-yield exopolysaccharide was screened and applied to the production of steamed bread. The research indicated that among 51 strains of L. sanfranciscensis, the highest yield of exopolysaccharide of L. sanfranciscensis Ls-1001 was 190.32 mg/L. Through the determination of various indexes in the dough fermentation process, the results showed that during the steamed bread production, the adding of L. sanfranciscensis could reduce the moisture of the steamed bread, increase the specific volume, reduce the pH value of the sourdough, increase the total acidity. The sensory quality of steamed bread made by active dry yeast been significantly improved. The research of this project is expected to promote the development of traditional fermented pasta products industrialization, and provide traditional fermented pasta with higher quality and nutritional value for the consumers.
Abstract:Using 3,5-dinitrosalicylic acid spectrophotometry, bengal red medium and MRS solid medium, the amount of sweet koji addition (0.5%-3.0%) on rice wine reducing sugar, pH, amylase activity, yeast was studied. The effects of the total number of bacteria and lactic acid bacteria, combined with the specific volume, texture and sensory score of the steamed bread, were comprehensively analyzed. The results showed that when the amount of sweet koji added was constant, the content of reducing sugar, amylase, total yeast and total lactic acid bacteria increased first and then decreased with the increase of time. The pH decreased first and then gradually decreased;the amount of sweet koji addition was 1.5%, and the protease activity in rice wine reached the maximum at 48 h. When the amount of sweet koji is less than 1.0%, the pH is higher, between 4.0-4.8. With the increase of the amount of rice wine sweet koji, the specific volume of steamed bread first increased and then decreased. The amount of sweet koji addition was 1.5%, the hardness and chewiness of steamed bread were the smallest, the recovery was the best, and the adhesion was the best (P < 0.05), the sensory score reached 92.0.
Abstract:Black rice effervescent tablets were prepared by acid and alkali separation wet granulation process, and the product formula of black rice effervescent tablets was optimized by orthogonal test. The results showed that the best puffing conditions was moisture content 16%, extrusion temperature 130 ℃, 28 Hz for the screw rotation, and the optimal formula of black rice effervescent tablet was composed of 7.5% puffing black rice powder, NaHCO3 and citric acid mass ratio of 1 ∶ 1, 8% xylitol, in order to improve the taste, also added 0.3% sucralose, 32.2% maltodextrin. Under the conditions, the effervescent tablets were weakly acidic and could be rapidly disintegrated. The amount of foam was 12.6 mL/g, and the solution was purplish red with certain precipitation.
Abstract:It is of practical significance to investigate the stability of vitamin C in complex vitamins (CVC) under different conditions, which will be helpful to improve the stability of vitamin C (VC) in the food system containing complex vitamins. In the present study, the content of vitamin C was determined by fluorescence analysis, and then the stability of CVC and VC was compared in different conditions including temperature, pH value, metal ions, light, redox reagents and carbohydrates, etc. The results showed that CVC displayed stronger heat resistance, alkali resistance and light stability than VC. The residue rate of CVC and VC decreased significantly as the hydrogen peroxide level increased, and was close to 0% after incubation with volume fraction 2.7% hydrogen peroxide. Moreover, epigallocatechin gallate didn't show concentration-dependence on improving the stability of CVC and VC, but lessened more CVC content than VC. Additionally, the effect of metal ions on CVC and VC stability was diverse, the residue rate of CVC was minimally affected by Mg2+ and Zn2+, but maximally by Fe3+ and Na+. However, the residue rate of VC was minimally affected by Na+, but maximally by Zn2+. Low concentration of glucose (≤5%) could only improve CVC stability, and high concentration of glucose (≥10%) could improve both CVC and VC stability. Together, these results indicated that CVC and VC exhibited different stability. Therefore, it should be adjusted processing conditions according to addition of the type of vitamin C in the food industry.
Abstract:PVA film is fully degradable, but it is weak in water resistance. In this study, nano-TiO2, acetic acid, urea and MgCl2 were added to PVA to improve the film property of water resistance. The mechanical, thermodynamics, microstructure and antibacterial properties of the films were investigated. It was found that the water resistance of the film had been greatly enhanced. The dissolution rate of the PVA-TiO2-MgCl2 film decreased about 73.32% compared to the PVA film, and the contact angle increased about 51.49%. The microstructure was observed by SEM and AFM, and found that the nanoparticles were evenly dispersed in the film. The bacteriostatic rate of the Mg2+ modified film for Escherichia coli and Staphylococcus aureus at the 24 h reached 34.98%, and 39.90%, respectively.
Abstract:There are kinds of food preservatives applied in the food industry, however, most of them only aim at gram-positive bacteria and have no effects on gram-negative bacteria. In order to develop new food preservatives with good antibacterial activity, molecular docking was carried out using UCSF DOCK6.5. The penicillin-binding protein 3 (PBP3) of Pseudomonas aeruginosa and PBP1b, PBP4 and PBP5 of Escherichia coli were chosen as the targets. ZINC database, containing 5 800 000 drug-like small molecules, was used for the virtual screening. After analysis, one of the hits was selected as lead compound and subjected to organic synthesis and food preservation. Compared with potassium sorbate, the lead compound was more effective on the control of pH value, total number of bacterial colonies, drop loss and TVB-N of chilled pork except color protection. But both of them had better results than control group. The research results proved that the lead compound had a better preservation effect on chilled pork, and it was expected to further develop it into a new food preservative.
Abstract:The synergistic effects of carvacrol, a quorum sensing inhibitor, combined with protamine on quality of turbot fillets during the cold storage were studied in this paper. The results showed that the treatment group could delay the deterioration of turbot fillets effectively, and total viable counts (TVCs), TBA, K value and TVB-N were lower than those of control group, and the inhibitory effect of compound preservatives was the best. The treatment group could maintain hardness and texture characteristics of turbot fillets, which could reduce the formation of free water, enhance the binding force of fish to water, and control the water distribution of fish. Carvacrol treatment group could extend the shelf-life about 2-3 d compared with the control group, and compound treatment group of the carvacrol and protamine could prolong the shelf-life about 6-7 d. Thus, carvacrol and protamine had synergistic preservative effects, which could inhibit the spoilage of chilled turbot effectively during chilled storage, and keep the good quality of turbot fillets.
Abstract:The effect of EPE vibration-damping packaging on the quality of blueberry during logistics transportation was studied, and the basis was provided for the logistics transportation and preservation of blueberry. First, the properties of three types of vibration-damping materials: EPE, bubble cushion and polystyrene (EPS) were compared, finding that the cushioning performance of EPE damping material was better than bubble cushion and EPS. Therefore, EPE materials with different thicknesses (4, 6, 8 mm) were used to study the vibration storage of blueberries. Compared with the control group, at the end of storage, the blueberry decay rate of 8 mm EPE vibration-damping material was only 17.2%, which was 0.51 times that of the control group, which could effectively reduce the blueberry fruit decay rate. The weight loss rate of the blueberry 8 mm EPE material treatment group at the end of storage was only that of the control group 39%. It delayed the increase in weight loss rate, titratable acid and soluble solids gradually decreased with storage time. At the end of storage, the 8 mm EPE group had the highest TSS content, which was 75.4% of the initial storage period, while the control group content was 37.4% of the initial storage period. The hardness change of the blueberry group of 8 mm EPE vibration-damping material was delayed. The anthocyanin content of the control group was the most abundant when stored for 14 d, the content was 1.96 mg/g, while the EPE group reached the highest content on the 28th day, which was 1.88, 1.93, 1.96 mg/g. The total phenol content of the control group reached the peak value of 5.675 mg/g on the 7th day, and the EPE treatment group had the highest content after 21 days of storage, and the 8 mm EPE damping material content was the highest. At the end of storage, the contents of MDA in each group were 17.5, 12.3, 11.5 μmol/L and 10 μmol/L, respectively. The content of EPE group was lower than that of control group, while 8 mm EPE group had the lowest content, which was the lowest of control group 57.1%, indicating that 8 mm EPE damping material cuuld reduce the changes in anthocyanins, total phenols and malondialdehyde content with storage time, which was helpful for the subsequent storage and preservation of blueberries.
Abstract:It is aimed to investigate the applicability for identifying Staphylococcus argenteus by GB 4789.10-2016 method, and then to establish a complementary method. Total 193 isolates of Staphylococcus aureus and 6 isolates of Staphylococcus argenteus were used in the identification with the both methods either recommended in GB 4789.10-2016 or PCR amplification of nuc1 and NRPS genes. And according to the results of biochemical characteristics and PCR amplification, it was unfortunate that S. argenteus strains were all falsely detected as S. aureus with the method recommended in GB 4789.10-2016 and the nuc1-PCR method, however, the NRPS-PCR method established in this study can distinguish these two species. Therefore, a new protocol was established based on the combination of GB 4789.10-2016 and NRPS-PCR to identify and distinguish S. aureus and S. argenteus.
Abstract:The toxicological properties of the new products in the pathway of sugar inhibition of PhIP was investigated by Discovery Studio(TOPKAT) toxicity prediction software, providing basic data for the comprehensive evaluation of food safety after reduction of heterocyclic aromatic amines. The results showed that the toxicity of the reaction products of α-dicarbonyl compounds with creatinine/PhIP did not change compared with PhIP in the mutagenicity (Ames test) and skin sensitization assessment. In the assessment of developmental toxicity potential (DTP), the toxicity of the reaction product of α-dicarbonyl compound with creatinine was enhanced compared with that of PhIP, while toxicity of α-dicarbonyl compound and PhIP reaction product did not change compared with that of PhIP. In the rat oral LD50 and rat chronic oral LOAEL toxicity level assessment, the majority of the reaction products of α-dicarbonyl compounds and creatinine showed greater toxicity than PhIP, whereas toxicity of α-dicarbonyl compounds and PhIP reaction products was weaker than that of PhIP. In rat inhalation LC50 assessment, the most of the reaction products of α-dicarbonyl compounds and creatinine/PhIP showed stronger toxicity than PhIP. Thus, the formation of α-dicarbonyl compounds and creatinine/PhIP reaction products have altered their toxicity.
Abstract:In order to evaluate the effect of heavy metal artificial antigen using heterocyclic Bifunctional Chelators(BFCs),S-2-(4-Aminobenzyl)-1,4,7,10-tetraazacyclododecane tetraacetic acid(P-NH2-Bn-DOTA, eg. DOTA)and heavy metal Pb2+ were selected. The artificial antigens were produced by glutaraldehyde method based on the Bifunctional Chelators DOTA. The conjugation ratios were 13 ∶ 1 and 9 ∶ 1 for immunizing antigen and coating antigen, respectively. The polyclonal antibody(PcAb) was obtained after immuring to rabbits. Based on the PcAb, an indirect competitive ELISA (ic-ELISA) was established and its linear regression equation was y=12.014ln(x)-13.249 (R2=0.9951). According to the ic-ELISA, the value of IC50 and IC20 were 193.4 ng/mL and 15.9 ng/mL, respectively. The specificity analysis showed that the cross-reactivities (CR) were all less 6.4% except Cd2+ was 18%, which indicated that the PcAb was specific for Pb2+. The produced Cu2+ artificial antigen and the PcAb could lay the foundation for rapid analysis of heavy metal residue using the BFCs.
Abstract:Tea polyphenols and phytic acid both can be used as food preservative. In this paper, the mixed solutions concentrations of tea polyphenols and phytic acid were simultaneously determined by spectrophotometr, and the interference was eliminated. The results showed that phytic acid had no effect on the coloration of tea polyphenols, and the concentration of tea polyphenols in the mixed solution could be determined immediately by ferrous tartrate coloration method. Tea polyphenols and phytic acid both had color development when the polyferric chloride-sulfosalicylic acid was a chromogenic agent, and the color development ability of phytic acid were affected by the mass concentration of tea polyphenols in the mixed solution. The interference of tea polyphenols on the color development ability of phytic acid could be eliminated by the mathematical simulation method, and the standard curve of phytic acid were obtained. By this method, the optimal determination range was the tea polyphenol mass concentration of 0-0.300 mg/mL, the phytic acid mass concentration of 0-3.000 mg/mL, and the recovery rate of 96%-103%. The method is simple to operate and has high accuracy, and it can provide a theoretical basis for simultaneous determination of mixed components.
Abstract:The application of Streptococcus thermophilus S10 and probiotics Lactobacillus plantarum P-8 compound fermented soymilk (S10+P-8), compared with commercial starter culture 1 and 2. Solid phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS) and relative area normalization method were used to study the fermented soybean milk sample, the volatile flavor compounds were studied by principal component analysis and cluster analysis. The results showed that 124 volatile compounds, including acids, ketones, aldehydes, alcohols, esters, hydrocarbons and nitrogen-containing compounds were detected, the main compounds were acids, ketones, aldehydes, and alcohols compounds. Compared with other samples, the volatile compounds in the S10+P-8 group had higher total peak area, numbers of volatile compounds and lower total amount of the compounds of beany flavor, and less hexanal content was 5.62%, the difference was significant(P<0.05). The results of principal component analysis of the samples with volatile flavor substances showed that the S10+P-8 group was significantly different from other samples, and positively correlated with ketones compounds and nitrogen-containing. The principal component analysis and cluster analysis results of samples and main volatile flavors indicated: the S10+P-8 group of samples were positively correlated with 2,3-butanedione, acetoin, acetic acid, caproic acid and acetaldehyde, these substances could present a characteristic aroma or fragrance of beans. It was clearly distinguished from other samples, significant difference (P<0.05).
Abstract:The aim to explore the bile salt deconjugation ability of lactic acid bacteria (LAB) strains from traditional fermented dairies in Western China included Qinghai, Gansu, Xinjiang, Tibet and Inner Mongolia, to provide reference for the effective development of microbial resources. The bile salt deconjugation ability of 275 LAB strains isolated from western traditional fermented dairies were determined by HPLC, analysis the different bile salt deconjugation ability among the different species and isolates’ sources, screening excellent strains. At the same time, the ability to produce γ-aminobutyric acid was determined for the selected strains, which provided a reference for the exploration of new resources of lactic acid bacteria and industrial production of gamma-aminobutyric acid. The results showed that, ①83 LAB strains were with bile salt deconjugation ability, and there had differences of isolating rates among different sources and species, Tibetan milk dregs showed a higher positive strain screening rate, strains L. paracasei, L. plantarum, L. breris and L. casei showed higher positive strains screening rate. ②There were significant differences of the bile salt deconjugation ability for GCA, GDCA, GCDCA, TDCA, TCA and TCDCA among all the BSH-positive strains (P<0.05), the deconjugation ability of glycine conjugating bile salt of were higher than taurine conjugating bile salt. ③For the different regions, there were significant differences of 4 bile salt deconjugation index in different areas BSH-positive strains, the dissociation capacity of bile salts from positive strains from Xinjiang and Tibet was significantly higher than that from Qinghai and Inner Mongolia (P<0.05). ④ For the different types of fermented dairies, there were significant differences of 3 bile salt deconjugation index in different dairies BSH-positive strains, the dissociation capacity of total bile salts in the positive strains in milk residue was significantly higher than that in acid horse milk and acid milk (P<0.05). ⑤For the different dominant BSH-positive strains, there were significant differences of 5 bile salt deconjugation index in different dominant strains, the dissociation ability of L. breris and L. plantarum to total bile salts was significantly higher than that of L. paracasei and L. casei (P<0.05). ⑥Analysis of ability of four excellent strains to produce γ-aminobutyric acid: L. breris and L. plantarum have higher γ-aminobutyric acid capacity, while L. paracasei and L. casei do not produce γ-aminobutyric acid. In conclusion, because of different species and isolates’ sources, the bile salt deconjugation ability for LAB stains were different. For the different sources, isolates from Koumiss, Shubat in Xinjiang and milk dreg in Tibet was with the highest bile salt deconjugation ability. For the different dominant strains, L. breris and L. plantarum was with the higher bile salt deconjugation ability, and it has the ability to produce high γ-aminobutyric acid, which can provide a theoretical basis for the development of excellent lactic acid bacteria species.
Abstract:Objective: GC-MS technology was used to study the volatile flavor composition of fermented brown rice milk with different formulas, and evaluate the product quality of fermented brown rice milk by using sensory evaluation parameters as indicators, with the purpose of providing a theoretical basis for the development of new products of germinated brown rice milk and the improvement of sensory quality. Method: Germinated brown rice drinks of different formulations were collected, and gas chromatography-mass spectrometry (GC-MS) was used to analyze the volatile flavors of germinated brown rice milk. The correlation between sensory attributes and volatile flavor components was then evaluated by partial least square regression. Results: Potential biomarkers were screened out according to database searching and MS information matching. A total of 21 volatile flavors were identified. Conclusion: 2,3-butanedione, acetoin, 2,3-pentanedione,1-heptanol and butyric acid were detected by GC-MS, which were the main flavor substances of germinated brown rice milk, were significantly correlated to the milk aroma, rice flavor and sourness.
Abstract:The objective of this study was to compare the chemical and taste properties of thermal reaction chicken flavor of breast, thigh meat and skeleton from commercial spent laying hens (SLH), Chinese San Huang chickens (SHC) and Arbor Acres broiler(AAB). The ages of SLH, SHC and AAB were 72 weeks, 10 weeks and 7 weeks, respectively. The results revealed that several different characteristic features for the three breeds, the skeleton of SLH had the lowest content of moisture and protein and the highest content of fat, which were 68.74%, 15.32% and 14.49%, respectively. For all samples, the degree of hydrolysis were positive correlated with the content of protein. The results of taste evaluation showed that the thermal reaction chicken flavor of SLH had the highest score, especially in respect of mouthfulness, continuity, acceptability and boiled chicken flavor. Compare to the SHC and AAB, the SLH was more suitable for used to produce the thermal reaction chicken flavor.
Abstract:Illumina MiSeq high-throughput sequencing technology was used to study the abundance and dynamic change of the fungi community in the fermentation processes of Dacha and Ercha of the traditional light-aroma baijiu. A total of 488 956 and 642 670 effective sequences and 14 230 and 7 303 OTU were obtained, which were classified into 26 subphyla or class including of Ascomycota, Basidiomycota, Zygomycota and the unclassified in fungi domain. The results showed that the species and quantity of fungi in the fermentation processes of Dacha and Ercha of the traditional light-aroma baijiu were abundance and changed with environmental change and fermented time. Saccharomycopsis, Saccharomyces, Candida, Hanseniaspora and Torulaspora were predominated microorganisms in Dacha or Ercha fermentation processes. The research above would lay a foundation for the further excavation of functional microbiology during fermentation process of the traditional light-aroma baijiu.
Abstract:Listeria monocytogenes is an important foodborne pathogen with high mortality rates. A total of 437 samples with 4 kinds of agri-food (fresh meat, egg, milk and vegetable) were collected from supermarkets, farmers markets and production base in Shanghai. L. monocytogens were isolated from these samples by GB 4789.30-2010 standard method, and the isolates serogroup was identified by multiple PCR. Results showed that total detection rate of L. monocytogenes was 14.9% (65/437). The percentage distribution of the isolates was 27.2% (61/224), 3.4% (2/58), 2.0% (1/51) and 1.0% (1/104) for raw meat, egg, milk and vegetable, respectively. All of 79 isolates were serotyped into five serogroups: 1/2a or 3a (55.7%, n=44), 1/2c or 3c (21.5%, n=17), 1/2b or 3b or 7 (17.7%, n=14), 4a or 4c (3.8%, n=3) and 4b or 4d or 4c (1.3%, n=1). This research represents the different prevalence of L. monocytogens in raw-foods in Shanghai, and partial isolates belong to high-pathogenicity. Our results will provide the fundamental data for epidemiological monitoring of L. monocytogenes in Shanghai.
Abstract:The management of raw materials for health foods is a key and difficult point in the registration and record-keeping management of health foods. This paper sorts out the concepts and material management methods of health food in the United States, Canada, the European Union, South Korea, Japan and Australia, and puts forward specific suggestions from learning foreign management experience based on the current situation of raw materials for health foods in China. The purpose of this study is to improve the regulation of management of raw materials and better service for the registration and record-keeping of health food products in China.