Abstract:Lychee, as a typical fruit of South China, was popular in domestic and oversea markets for its delicious tastes and health promoting effects. In recent years, a lot of studies have focused on the bioactive components and health effects of lychee. This paper summarized the chemical structures and distribution characteristics of polyphenols and polysaccharides in lychee pulp. Procyanidines and flavonoids were the main polyphenols in lychee pulp while heteropolysaccharides were the main polysaccharides, which possessed a large number of fractions with different molecular weights and structures. Lychee pulp with different cultivars had different polyphenols and polysaccharides contents while feizixiao and nuomici were the best cultivars. The antioxidant, hepatic protection, lipid metabolism improvement, and immunomodulatory activities and their action mechanisms of polyphenols and polysaccharides were summarized. Moreover, changes of polyphenols and polysaccharides during the process of lychee were introduced. This review will provide inferences for the lychee's intensive process.

Abstract:Edible mushroom is a kind of macrofungi with different varieties, which is rich in nutrition and has delicious taste and abundant active substances. Some significant breakthroughs have been made for the breeding and industrialized cultivation techniques of edible mushroom in the last ten years in China, leading to the rapid increase of edible mushroom production. However, fresh edible mushroom is still the main consumption pattern in China, which accompanied with the weak processing chain, low processing rate, less processed products, and low-value products of edible mushroom. These lead to the overstock of fresh mushroom and the instability for mushroom industry. Less profits of edible mushroom during foreign exports and domestic market seriously restrict the further development of the edible mushroom industry. This article has reviewed the main problems and the current development situation of the edible mushroom industry in China, and then analyzed the development tendency and prospects for the edible mushroom processing industry. This paper will provide guidances for the stable and healthy development of edible mushroom industry in future.

Abstract:Edible mushrooms are delicious and healthy foodstuffs. Wild edible mushrooms are favored for their texture and flavor as well as for their nutritional points. Environmental pollution of cadmium, lead, mercury, and arsenic is becoming more and more serious. The main exposure route of humans to harmful pollutants in the environment is by ingestion though food chain. So, cadmium, lead, mercury, and arsenic are considered as typical toxic elements in foods. Compared with vascular plants, macrofungi showed high contents of heavy metal elements, including cadmium, lead, mercury, and arsenic. This paper mainly summarized the levels of cadmium, lead, mercury, and arsenic in edible mushrooms, the distribution of heavy metals in fruiting body, and the bioaccumulation of edible mushroom to heavy metals. It specially focused on the research status of the bioaccumulation of wild edible mushrooms to cadmium, lead, mercury, and arsenic. From the studies, the cultivated edible mushrooms could show low contents of cadmium, lead, mercury, and arsenic, by breeding superior varieties and improving production conductions and cultivation techniques. According to the standards, cultivated samples have high qualification rates. However, wild edible mushrooms have a lot of varieties, and their growth conditions are uncontrolled. It is necessary to carry out further researches on the risk assessment of food safety of wild edible mushrooms, and develop quality control technologies of products from wild edible mushrooms to protect consumer’s health.

Abstract:Cross-linked enzyme aggregates (CLEAs) of alkaline protease play a crucial role in food, medicine, brewing, silk, leather, and other industries CLEAs were successfully prepared and characterized in this paper. Under the optimum preparation conditions (90% tert-butanol as the precipitant, precipitated time of 15min, glutaraldehyde concentration of 33mmol/L and cross-linking time of 6h), the activity recovery of CLEAs recorded 22.6%. In addition, the CLEAs displayed a shift in optimal pH towards the alkaline side from 7.5 to 8.0, and their optimal temperature was also improved to a certain extent compared to free enzyme from 60℃ to 65℃. The enzymatic kinetics studies indicated that the CLEAs (4.3min-1) were more efficient than the free enzyme (3.7min-1) in catalyzing casein hydrolysis. Although the V_max of CLEAs (9.8mg/(mL·min)) was lower than that of free enzyme(13.3mg/(mL·min)), the substrate affinity of CLEAs(2.3mg/mL)increased compared with the free enzyme (3.6mg/mL). The CLEAs also enhanced the thermal and pH stability of alkaline protease. Moreover, after being used repeatedly for 5 and 8 batches in phosphate buffer, CLEAs retained 82.5% and 56.5% of their initial activity.

Abstract:In order to achieve high expression of Trichoderma viride β-glucosidase in recombinant Pichia pastoris,the fermentation conditions of the P. pastoris KM71/pPIC9K-bgl1/pPICZ A-pdi were optimized in a 3.6L bioreactor. When the optimal conditions were the induction temperature 28℃, initial cell density 50g/L, and methanol volume fraction 1.0%, fermentation of P. pastoris KM71/ pPIC9K-bgl1/pPICZ A-pdi yielded an enzyme activity of 1452U/mL. β-glucosidase from the recombinant strain was immobilized on chitosan cross-linked with glutaraldehyde. When the optimal conditions of immobilization were 0.03g/mL chitosan, 0.008g/mL glutaraldehyde, 400U/g chitosan beads, and adsorption time 20h, the immobilization efficiency reached up to 65.4%. The yield ratio was still up to 15.2% after 6 times of continuous conversion and it showed a good operational stability and a high productivity of gentiooligosaccharides.

Abstract:The β-glucosidase gene bglHi, bglAa and bglAn, derived from Humicolainsolens, Aspergillus aculeatus and Aspergillus niger were heterologously expressed in Pichia pastoris GS115, respectively. The pNPG was selected as the substrate to investigate the properties of three enzymes.The optimum reaction temperature ranged from 55℃ to 65℃ while the pH value ranged from 5.0 to 6.0. The enzyme activity of BglAn was the highest, which was up to 90.83U/mg.Three enzymes with different concentrations were used to hydrolyze mogroside V under the conditions as follows:pH 6.0, temperature 50℃ and enzyme amount 2U. The results showed that there was significant difference among the substrate specificity of different β-glucosidases. The conversion rate of mogroside V to mogroside ⅢE of BglHi and BglAa was only 5%-7%. Meanwhile, the conversion of 1mg/mL substrates by BglAn was 96.5% when the enzymatic time was 20 min. When the concentration of substrate was increased to 5mg/mL, the conversion rate could reach 97.9% at 1h. This study could provide a novel strategy for the development of mogroside sweeteners with different structures and functions.

Abstract:In this study, four strains of lactic acid bacteria were obtained from four kinds of traditional royal cheese using gradient dilution method and scribing purification method, and then rescreened by acid production experiment and catalase experiment. Through morphological observation and molecular identification of 16S rDNA sequence, two strains were identified as Enterococcus faecium (MRSA1 and MRSB1), and the other two strains were identified as Leuconostoc lactis (MRSA2 and MRSD3). The bacteriostatic test showed that Leuconostoc lactis(MRSA2) had good antibacterial properties against Escherichia coli, Shigella and Salmonella. All four strains had antioxidant activities, and the DPPH radical scavenging ability and hydroxyl radical scavenging ability of the bacterial suspension were higher than those of cell-free extracts. The DPPH and hydroxyl radical scavenging ability of MRSA2 suspension were 60.67% and 31.86%. The strains of lactic acid bacteria (MRSA2) with antibacterial and antioxidative activities obtained in this study provided a foundation for their application in functional dairy foods.

Abstract:D-Psicose can be converted from D-fructose catalyzed by D-psicose-3-epimerase. To realize the heterologous expression of D-psicose-3-epimerase (DPEase), the primers were designed to clone and isolate the gene. The DNA sequences and structural characteristics of DPEase were analyzed by bioinformatics. The results showed the gene possessed 870bp open reading frame and encoded 289 amino acids. Alpha helix, beta folding, and random coil respectively accounted for 38.41%, 47.06%,and 14.53% in the secondary structure of the protein. The protein located at the cell membrane belonged to a hydrophilic protein without the signal peptide and transmembrane region. The prokaryotic expression vector was constructed and transferred into the E. coli BL21. The molecular weight of DPEase was appropriately 33kDa. After an induction of 1mmol/L IPTG for 28h, the protein amount and enzymatic activity of the recombinant E. coli BL21 were 0.32g/L and 3.8U/mL. The DPEase gene of A. tumefaciens could be expressed in the engineered E. coli.

Abstract:In order to investigate the diversity of the bacterial community in fermented fish products, the bacterial community were investigated by 16S rDNA V4-V5 region sequence and phylogenetic relationship analysis using the Illumina HiSeq sequencing platform. The average number of sequences obtained from samples was 46463. Operational taxonomic units (OTUs) of fresh and salted samples were 1064 and 952. OTUs of samples fermented for 5,0, 20, and 25 days were 454,2, 327,2, and 356, respectively. The overall bacterial composition of the seven groups samples was complicated,including 196 family in 38 phyla, and Firmicutes was absolutely dominant,followed by Proteobacteria and Cyanobacteria, and the main dominant family were Enterobacteriaceae, Enterococcaceae, Leuconostocaceae, Lactobacillaceae, and Streptococceae.We found that there were diversities in the abundance of bacterial species in each sample and the microfloral composition was closely related to the production process.This method might provide a scientific support for the traditional industry.

Abstract:The volatile aroma compounds of apple brandy with different aging time in oak barrel were determined by liquid-liquid extraction and gas chromatography-mass spectrometry and analyzed by cluster analysis methods. The results showed that 90 kinds of compounds were identified in apple brandy during the aging process, including 43 kinds of esters,32 kinds of alcohols, and 15 kinds of acids. With the prolonging of aging process, the quantity and total content of the common esters and acids of apple brandy were increased, while the total content of common alcohols were decreased. And trends of the number of acid aroma components were increased firstly and then decreased. In the process of aging, the aroma components in apple brandy have a dynamic process of generation, replacement and disappearance. The results of cluster analysis showed that the whole aging process was clustered into 3 groups with the change of volatile aroma compounds. Different kinds of apple brandy showed the different flavor characteristics.

Abstract:Based on the optimized process for aflatoxin B₁(AFB₁)removal through the ultra high pressure-assisted enzyme treatment, the quality of rice bran polypeptides has been evaluated. Under the ultra high pressure of 300MPa, the yield, degree of hydrolysis, solubility, foaming stability, emulsification and emulsifying stability of polypeptides increased first and then decrease when the treatment time increased from 0 to 9min. The foamability and oil retention of polypeptides significantly improved while the water retention decreased. The process could remove aflatoxin from rice bran polypeptides and improve the quality of rice bran.

Abstract:The combined application of transglutaminase (TGase) and glucono-δ-lactone (GDL) in the preparation of color soft tofu was optimized by the response surface methodology. Vegetable juice was added into soymilk as natural dyes. Using the springiness and cohesiveness of color soft tofu as key response values, the response surface model about the concentration of coagulants and the temperature for soymilk coagulation were set up. The most important effect on texture of color soft tofu was the temperature of coagulation. The models were reliable and could be used to predict the springiness and cohesiveness of color soft tofu. The optimum conditions of the color soft tofu preparation were confirmed as follows:TGase concentration of 1.4g/L, GDL concentration of 1.7g/L, and the coagulation temperature for soymilk gel formation of 53℃. Verified by the sensory evaluation experiment and texture profile analysis, the color soft tofu showed better characteristics than lactone tofu in the market. This optimal conditions for color soft tofu preparation could be helpful to diversify tofu products.

Abstract:An ultra performance liquid chromatography-tandem mass spectrometry (UPLC- MS /MS) method for the determination of five carbamate pesticides in spinach was established. Samples were homogenized and extracted by ultrasonic with acetonitrile-water(50∶50 in volume ratio), and then salted out and purified with primary secondary amine sorbent. Under the electrospray ionization (ESI+mode), data of the target parent ions and product ions were collected with mass spectrometric multi-response monitoring scanning detection. The matrix calibration curves of five carbamate pesticides showed the good linearity within the concentrations of 0.1-20.0μg/L with the good correlation coefficient (r＞0.9991). The average recoveries of three spiked levels ranged from 91.0%-101.0%, while the limits of detection and limits of quantitation were 0.10-0.20μg/kg and 0.25-0.50μg/kg, respectively. The relative standard deviations were 2.15%-5.57%. This method has good sensitivity and high precision, which is suitable for practical determination of five carbamate pesticides in spinach.

Abstract:Complementary foods is one of the important nutrient sources for infants and young children, and most countries have formulated standards or regulations for complementary foods. The similarities and differences of complementary food standards of CAC and of main developed countries have been summarized and compared with related standards of China, including the legislative body, coverage of standard, regulatory effects, product categories, raw material requirements, nutrient ingredients, contaminants,and analyzed these similarities and differences between them. This study could provide references for the revision of national food safety standards for complementary foods for infant and young children.