Abstract:Engineering thermostability of lipase is a hot topic of improving properties of the enzyme. With the development of technology, more and more effective means are used in engineering thermostability of lipase. This paper summarizes the main factors influencing the thermostability of lipase, methods to improve it and the latest research results on it. It could provide a basis for further research on lipase and a reference for altering character of other enzymes.

Abstract:Based on upconversion fluorescence labeling, magnetic separation and immunological recognition, a novel detection method of Vibrio parahaemolyticus was constructed. Primarily, the NaY0.78F4: Yb0.20, Er0.02 upconversion nanoparticles(UCNPs) were synthesized through hydrothermal method, and then amino group was modified on the surface of UCNPs. Meanwhile, amino-modified MNPs were synthesized by one-step process. Secondly, the antibodies of Vibrio parahaemolyticus binding with MNPs and antibodies of flagellin binding with UCNPs were used as capture probes and signal probes, respectively. The composite of MNPs-target bacteria-UCNPs was obtain, and detected by 980 nm laser. Under the optimum conditions, the upconversion fluorescence was a good linear in the range of 5×103~5×105 cfu/mL of Vibrio parahaemolyticus, and the detection of limit was 1×103 cfu/mL. This method was accurate in the recovery text in the crucian.

Abstract:Isoamylase is able to cleave α-1, 6-linkages in amylopectin, which is essential for starch saccharification. Research on mechanism of Thermobifida fusca isoamylase(IAM) by instrumental analysis methods has not been reported. In this study, IAM was purified by affinity chromatography and used to hydrolyze amylopectin from maize(AP). Results of size exclusion chromatography (SEC) indicated that IAM hydrolyzed both inner and outer branching linkages of amylopectin. The polymer structure was completely destroyed by IAM and the mean molecular weight(Mw) decreased from 2 812 000 to 760 000 and 7.2 000 after 2 h, the ratio of large glucans to the small ones was 1∶4.4. The population of starch fragments released was characterized by high performance anion exchange chromatography with pulsed amperometric detector(HPAEC-PAD), the degree of polymerization(DP) of final hydrolysates distributed mainly in 15~35, released maltose and maltotriose demonstrated that the smallest units hydrolysed by IAM were side chains with 2~3 glucose residues. 1H nuclear magnetic resonance(1H-NMR) spectrum showed that IAM specifically and completely cleaved α-1, 6 glycosidic linkages and produced amylose chains or maltoligosaccharides with α- or β-anomeric reducing ends. The mechanism analysis of IAM could lay the foundation for its applications.

Abstract:According to the results of single factor experiments and response surface analysis of Box-Behnken experimental design principle, the factors that influence the extraction rate of the organic acids in grapes were optimized. The 3 factors were solid to liquid ratio, the volume fraction of ethanol and pH value. The results showed that the optimum extraction conditions for organic acids in grapes were as follows: the solid to liquid ratio was 1∶16(g/mL), the volume fraction of ethanol was 76.37% and the pH value was 11.87. Under this condition, the extraction mass fraction of organic acids in grapes was 216.907 μg/g. The absorption spectra of complexes that generated by citric acid, tartaric acid and malic acid with copper sulfate were overlapping seriously. So it's very difficult to separate each component with photometric method. In this paper, the partial least squares method was used for simultaneous determination of the simulation ofmixed citric acid, tartaric acid and malic acid complexes. And the method was also be used in the determination of organic acids in grapes. To the analog mixed sample the recovery rate was 99.6%~99.8%, and the RPEs was 0.64%~0.67%.

Abstract:Buckwheat protein isolate(BPI)-dextran covalent conjugate was prepared by the Maillard reaction in macromolecular crowding environment in aqueous solutions. The effects of reaction time on solubility and emulsification were researched at 60 ℃ and 70 ℃. The results show that the conjugates obtained at 70 ℃ for 6 h have better emulsification and thermal stability with little browning. Besides, the formation of covalent complexes was verified by SDS-PAGE with both protein and carbohydrate staining, the fluorescence spectra showed that the protein hydrophobicity was enhanced by heating process.

Abstract:Ultrasonic-assisted Saponificationmethod was used to extract carotenoids from wolfberry pomace and the contents of carotenoids were detected. Based on single factor tests of different potassium hydroxide congcentration, temperature, time and ultrasonic power, the optimum extration process was evaluated by Box-Behnken central composite experimental design and response surface methodology analysis. The results showed that the optimal saponification processing parameters of carotenoids as followed: concentration of potassium hydroxide 1.8 mol/L, saponification temperature 40 ℃, saponification time 1 h, ultrasonic power 205 W. Under these compared with the predicted value 128.099 mg/hg, which indicated the degree of fitting was good and the saponification processing was accurate and reliable.

Abstract:Compared to All-E lycopene, Z-isomers had higher biological activity and bioavailability, but tending to oxidative degradation and conversion to E-isomer. In the paper, YMC Carotenoid C30-HPLC system were used to detect the influence of temperature on isomers' stability. The results showed that the proportion of cis-isomer lycopene could reach 78-85% in ethyl acetate by combining refluxing-crystal techniques. Storage stability test showed that the lower the temperature was, the smaller of degradation rate constant(k) of lycopene isomers was, indicating that the slower rate of degradation, more stable the storage. While the model parameters indicated that under isothermal conditions, kAll-E＜k9-Z＜k13-Z. The activation energies of 9-Z, 13-Z, All-E and All-Z isomers were 46.42 kJ/mol, 29.19 kJ/mol, 56.94 kJ/mol and 32.45 kJ/mol during storage respectively. So stability order of three major lycopene isomers was: All-E＞9Z＞13Z. And the activation energy of high proportion of Z-lycopene isomer product was 33.76 kJ/mol.

Abstract:150 healthy Kunming mice were randomly divided into three batches(5 groups each batch) for loaded swimming test and biochemical analysis. We divided Maca into low, medium and high dose groups(0.03 g/ kg.bw.d, 0.30 g/kg.bw.d, 1.00 g/kg.bw.d), and the control group(saline), positive control group(YiKang capsules for 0.30 g/ kg.bw.d) respectively. Mice were administered ig daily for 30 d, then the loaded-swimming time, blood urea nitrogen, blood lactate, hemoglobin, lactate dehydrogenase and hepatic glycogen of them were measured．In addition, active ingredients related to anti-fatigue in Maca such as amino acids, polysaccharides, fructose and glucosinolates were quantitative detected through colorimetry or HPLC. Results show that, Maca is rich in amino acids(158.10 mg/g), total flavonoids(20.83 mg/g), polysaccharides(37.16 mg/g), fructose(31.27 mg/g), total alkaloids(4.22 mg/g), mustard oil glycosides(1.08 mg/g) and other ingredients. Animal testing results show that, the high, middle, low dose groups could all significantly prolong the time of loading swimming, increase the hemoglobin, lactate dehydrogenase and hepatic glycogen, decrease blood urea nitrogen and blood lactate in mice compared with negative control. Maca is rich in a variety of active ingredients related to anti-fatigue, and it has significant anti-fatigue function in healthy mice, may be ideal raw material for anti-fatigue functional foods.

Abstract:Mannose-oligosaccharides and mannose glycoprotein play an important role in many physiological processes, their synthesis is a vital branch of carbohydrate chemistry. Mannosyl trichloroacetimidate is a very efficient glycosyl donor in their synthesis. This paper investigated the new microwave assisted synthesis of mannosyl trichloroacetimidate, and optimized the traditional synthetic method. It was synthesized from D-mannose by benzoyl protection, hydrolysis and then reaction with trichloroacetonitril. Its existing methods were optimized and total yield was more than 85%. Meanwhile it was synthesized by the microwave assisted method firstly. The experiment result indicated the total yield in new method was more than 12% compared with that in traditional method, while the reaction time was shortened about 15 times.

Abstract:Acerola contains a lot of vitamin C, but vitamin C is very unstable and easily oxidized. Study the effects of different processing and storage conditions on the content of vitamin C in acerola turbid juice. Cooling and aseptic packaging process after UHT sterilization saves the highest rate of vitamin C, as 94.56%. Vitamin C of products packed in Tetra Pak packaging material saves the highest rate of 76.42%. In terms of storage temperature, it is not the lower, the better. And the ambient temperature of 15~20 ℃ saves the highest rate of vitamin C.

Abstract:The wild blueberry as raw materials was used to get its anthocyanins, and the anthocyanins were purified、heated at 121 ℃ for 6min and then got into simulated gastrointestinal environments. The antioxidant activity of the treated samples were measured and then take a comparative analysis, as to know the effects of the purity and external environment on the antioxidant activity of anthocyanins. The results showed that: under the same processing environments, the antioxidant activity of anthocyanins in aqueous solution enhanced significantly with the purity increasing. The activity of the secondary purified was about 4 times than that in crude extracts. But the effects from purity in simulated gastrointestinal environments were smaller. In the same purity, the antioxidant activity of the anthocyanins were reduced greatly after the heating treatment and simulated gastrointestinal environment, the anthocyanins activity in aqueous solution was 2 times above than that in simulated gastrointestinal environment. The antioxidant activity of anthocyanins were greatly reduced after heated at 121 ℃, and a loss of activity about half was occurred under the same conditions. However, this loss in simulated gastrointestinal environment was smaller. The crude anthocyanins activity in aqueous solution was 2.7 times than that which heated at 121 ℃.

Abstract:The optimization of the ultrasonic-assisted extraction of total alkaloids from Plumula Nelumbinis by response surface methodology was studied. Based on the single-factor test analysis, the Plackett-Burman experimental design and steepest ascent design, while take extracted amount of total alkaloids as the response value, response surface method was applyed to analyze the influence of various factors and their interaction on the extraction of total alkaloids, select an optimized progress to extract total alkaloids from Plumula Nelumbinis. In this study, nonlinear mathematical model fitting way make independent variables and the dependent variable relationship extend to curved surface, so that the experimental data become more precise. The experiments obtain an optimal ultrasound-assisted extraction of total alkaloids from Plumula Nelumbinis progress conditions: solid-liquid ratio as 1∶40.4; volume fraction of ethanol as 64.4 %; ultrasound extraction time as 40 min; model predict its productive yield can reach 128.695 mg/g. Under these conditions, extracted amount of total alkaloids from Plumula Nelumbinis can reach 128.673 mg/g, which is consistent with the predicted values.

Abstract:In order to improve the antibacterial effect of lysozyme on Escherichia coli and other gram negative bacteria, according to the single-factor experiments and orthogonal methodology was employed to optimize the Iodoacetamide modified lysozyme. The results show that 0.06 mol/L iodine acetamide and 5 mg/mL lysozyme bacteriostatic effect is best. The biggest inhibition zone diameter to the Escherichia coli is 25.7 mm when the reaction temperature is 45 ℃, reaction time is 30 min, and pH is 5. The antibacterial circle diameter is 2.7 times of the original. The biggest inhibition zone diameter to the salmonella is 24.1 mm when the reaction temperature is 55 ℃, reaction time is 70 min, and pH is 6. The antibacterial circle diameter is 2.6 times of the original. This was considered that egg white lysozyme after iodoacetamide modified, can be used for Gram-negative bacteria (E.coli K12, salmonella) inhibition, and the effect is good.

Abstract:The article has studied the inhibition effect of plant essential oil on common microorganisms in aquatic product. Method: Filter method is used to determine the bacteriostatic circle diameter of plant essential oil。As a result, three kinds of essential oils are selected. Then test-tube gradient dilution method is developed for the determination of three kinds of essential oil about bacteria minimal inhibitory concentration(MIC). Checkerboard dilution method is used for evaluating the joint bacteriostatic effect of oils by FICI value. Conclusion: Through the determination of bacteriostatic ring, cinnamon oil, Perilla oil and clove oil are selected. Each essential oil of antimicrobial MIC value range are: 0.313～0.625, 0.625～2.50, 0.625～2.50 μL/mL. Checkerboard dilution method results show that the distribution of essential oils for six antimicrobial showed synergistic and additive effect; there is no independent role and antagonism.

Abstract:Pu-erh tea is a kind of tea which uses sun dried green tea as its raw material and processed with a unique technology. Microbial fermentation plays a key role in the formation of Pu-erh tea quality. To improve the quality of Pu-erh tea and reduce fermentation time, some microbes with tea polyphenols conversion activity were isolated and identified from Pu-erh tea samples. After several rounds of screening, three strains with high ability of conversion tea polyphenols to theabrownin were obtained. After the three strains were inoculated to Pu-erh tea solid fermentation, the conversion process of tea polyphenols to tea pigments was obviously stimulated. Meanwhile, the ratio of three pigments have become better. The results of molecular identification showed that these three strains were Aspergillus niger, Candida blankii and Aspergillus awamori, respectively.

Abstract:To observe the long-term toxicity and its severity of Tibetan Radix Rhodiolae Changbaishan Wild Ginseng by rat experiment and provide safe dosage for its clinical usage. The rats were randomly divided into four groups: high(2.0 g/kg), middle(1.0 g/kg), low(0.5 g/kg) group and blank group. The drug group was given oral of Tibetan Radix Rhodiolae Changbaishan Wild Ginseng for 180 consecutive days and observe the changes of the rats' common condition、body weight、hematology、blood biochemistry 、liver and kidney function、coefficient of important organs 、histological during medication and the recovery condition within 30 days of stopping medication. Results shows the long-time use of Tibetan Radix Rhodiolae Changbaishan Wild Ginseng may have a certain impact on some indicators of live function、kidney function、creatine kinase、blood lipids and blood. This experiment indicates that the safe dose of its long-term use should not more than 0.5 g/kg daily.

Abstract:Environmental degradation has been a great concern for Chinese people. Sustainable management serves a critical avenue to solve environmental problems。The aim of this article is to propose an integrated evaluation framework through constructing a comparatively comprehensive set of indicators so as to measure food supply chain sustainability. The assessment methodology is the integration of Entropy and TOPSIS which are utilized to ascertain the weights of indicators and provide comparison and contrast amongst different food supply china. This article also provides a practical application of the methodology by comparing vegetable and chicken supply chains in China with those in Britain. Computational results show that vegetable and chicken supply chains in China is less sustainable compared with those in Britain. Scholars and practitioners in the sphere of sustainable research in China could utilize the findings of the article to take corresponding countermeasures to improve the sustainable performance of food supply chain so as to relieve the increasingly severe environmental problems.

Abstract:The financing efficiency of agro-food processing enterprises is related to investment in technological innovation, and directly affects food safety. This paper chooses the method of DEA-malmquist to access 30 agro-food processing enterprises' real condition of financing efficiency and technological innovation capability from 2007 to 2012, taking the listed companies' dynamic panel data of China as the research object. According to the analysis, this study puts forward following conclusions and suggestions: China's agro-food processing enterprises have ignored the importance of saving the cost of financing instead of being concerned about their own profitability and growth prospects, which resulted in lower debt financing efficiency , worse innovation capability and a risk of food safety.