Abstract:Aquatic products are very susceptible to spoilage, which requires certain measures to inhibit spoilage and deterioration. As a new and efficient broad-spectrum cold sterilization technology, cold plasma (CP) can achieve uniform and stable discharge under atmospheric pressure, and has a good killing effect on the common pathogenic and spoilage bacteria in aquatic products, which can extend the shelf life of aquatic products. The generation modes, the mechanism of microorganism inactivation and the factors affecting the sterilization effect of CP were reviewed in this paper. Meanwhile, the killing effect of CP on different kinds of microorganisms and the effect on the quality of aquatic products were also discussed, aiming to provide the reference for the application of CP in the preservation of aquatic products.

Abstract:The unique flavor and biological functions of coffee make it one of the top three beverages in the world. The high daily consumption per capita makes it one of the food sources with high acrylamide intake. Therefore, taking effective measures to reduce the content of acrylamide in coffee drinks has always been a hot issue of global concern. The acrylamide content in the final product could be affected by all the processing stages of coffee beverage production (including raw material selection, roasting, milling, brewing, conditions of storage, and etc.). This review summarized the reduction measures of acrylamide in all aspects of coffee beverage production, focusing on the methods to reduce the content of acrylamide precursor in raw coffee beans, the roasting conditions to inhibit the formation of acrylamide, and the measures to reduce the retention of acrylamide in coffee drinks, with an aim to provide beneficial enlightenment for the production of safe and healthy coffee drinks.

Abstract:Butyric acid is the preferred energy source for colon epithelial cells, which improves the integrity of the intestinal barrier and promotes human intestinal health. It has been reported that Hericium erinaceus β -glucan (HEBG) promotes the production of butyric acid by human intestinal flora, but the regulatory mechanism remains unclear. In this paper, the preparation methods of HEBG and the obtained HEBG with different structural characteristics were reviewed. Then, this paper summarized the bacteria with the characteristic of producing butyric acid in human feces, and reviewed the research progress of the mechanism of β-glucan regulating the intestinal bacteria producing butyric acid from different sources. It is concluded that Hericium erinaceus β-glucan is an excellent dietary fiber, which may promote the production of butyric acid by human intestinal flora through direct or indirect mode. This review has guiding significance for the development of the probiotics of β-glucan and the creation of healthy food of Hericium erinaceus.

Abstract:This study aimed to use the waste shrimp shell meal as a nitrogen source for the production of single cell protein from Clostridium tyrobutyricum. We investigated the effects of different amount of shrimp shell meal on the growth and production of short-chain fatty acids (acetic acid and butyric acid) of the strain, and determined the content of crude protein, crude fiber, crude fat and the composition of amino acid in the single-cell protein obtained by fermentation of shrimp shell meal by Clostridium tyrobutyricum to comprehensively evaluated the nutritional value of the protein feed. The results showed that the best growth performance was achieved at a carbon to nitrogen ratio of 8∶1.75 between glucose and shrimp shell meal, which produced 1.68 g/L of acetic acid and 3.45 g/L of butyric acid. After the fermentation of shrimp shell meal, the content of crude protein, crude fat and crude fiber increased by 7%, 117% and 92%, respectively, while the content of ash decreased by 13%, compared with those of shrimp shell meal. In addition, the feed contained a rich variety of amino acids, and 12 of the 16 amino acids were increased accordingly compared to the raw material. Finally, combined with the gain of nutritional composition before and after fermentation and the increase of short-chain fatty acids among them, the single-cell protein feed produced by Clostridium tyrobutyricum fermentation of shrimp shell meal is rich in nutritional value, green in production and cheap in cost, which is a novel potential protein feed.

Abstract:Phosphoenolpyruvate, the precursor of L-threonine synthesis, is consumed by the nitrogen phosphotransferase system (PTSNtr) of Escherichia coli, so the deletion of genes related to PTSNtr may affect the synthesis of L-threonine. In this study, ptsP, ptsO and ptsN genes encoding the component proteins of PTSNtr in E.coli MG1655 were deleted using CRISPR-Cas9 system, and the corresponding mutants MZ001, MZ002 and MZ003 were constructed. The results showed that the single deletion of ptsP、ptsO or ptsN led to slower growth in the early stage and longer lag period. The mutant strains grew fast in the later stable stage and their biomass accumulation was greater than that of the original strain. Then, the expression plasmid pFW01-thrA*BC-rhtC, which contained thrA*、thrB and thrC encoding threonine synthesis as well as rhtC encoding threonine transporter, was introduced into the original and mutant strains. In comparison with MG1655/pFW01-thrA*BC-rhtC, the L-threonine titer of MZ001/pFW01-thrA*BC-rhtC, MZ002/pFW01-thrA*BC-rhtC and MZ003/pFW01-thrA*BC-rhtC significantly increased by 3.805 g/L, 1.722 g/L and 3.091 g/L, respectively. The results showed that the deletion of genes related to PTSNtr of E. coli promoted the synthesis of L-threonine

Abstract:In order to explore the effect of glutenin, gliadin and their different proportions on the quality of bread, gluten, the extracted glutenin and gliadin from wheat gluten were respectively added into bread, and the qulity of bread was evaluated based on the specific volume of various breads. The results showed that all of them could increase bread specific volume. The improvement effect of glutenin and gliadin was comparable when they were added at a mass fraction of 1.5% (calculated on the amount of flour). The glutenin and gliadin were then added into the bread at a new ratio. The specific volume increased by 11.4% and the hardness of bread decreased, compared with that of the blank group, when the ratio of glutenin/gliadin was 3:1 and they were added at a mass fraction of 1.1% (calculated on the amount of flour). After 5-day storage, the hardness increment of bread was 13.1% which was lower than that of the blank group, indicating an inhibition on bread aging. This anti-staling effect was more effective than that of bread with gluten added at a mass fraction of 1.5% (calculated on the amount of flour).

Abstract:The preparation of selenium nanoparticles from microorganism had low toxicity, mild synthesis and other advantages, showing broad application prospects. A strain which could reduce sodium selenite to selenium nanoparticles was isolated and purified from the soil with supplemental selenium fertilizer in Wuhan. The strain was identified, and its selenium tolerance and growth kinetics curve were determined. The selenium nanoparticles were characterized by scanning electron microscope, and the inhibitory activity of selenium nanoparticles and the secondary metabolites on α-glucosidase were preliminarily explored. The results showed that among the 16 strains isolated and purified, the maximum tolerance concentration of Cytobacillus firmus N4 to sodium selenite was 36 mg/mL with the selenium nanoparticle size of 150~220 nm. When the concentration of selenium nanoparticles was 0.625 mg/mL, the inhibition rate of α-glucosidase was 25.42%±0.69%, and the inhibition rate reached to 73.83%±4.63% when the concentration of secondary metabolites was 2.500 mg/mL. Cytobacillus firmus N4 has high selenite-tolerance, providing the basis for the biotransformation of selenium nanoparticles, and its secondary metabolites show certain α-glucosidase inhibitory activity, which is worthy of further study.

Abstract:Pediococcus damnosus(P. damnosus) is one of the most commonly-found beer-spoilage bacteria in breweries. This study compared the ability of biofilm and planktonic cells of beer-spoilage P. damnosus to enter a viable but putatively non-culturable (VBNC) state. Planktonic and biofilm cells of five beer-spoilage P. damnosus were cultured at 26 ℃ in the lager beer. The results showed that both biofilm and planktonic cells could be induced to enter the VBNC state, however, the state-transition time was variable. It took a minimum of 70 days for the biofilm cells to enter the VBNC state, while 126~189 days for the planktonic cells. The presence of VBNC cells in biofilms was further confirmed by PCR coupled with propidium monoazide pretreatment that amplified genes 16S rDNA and horA. In addition, the biofilm cells were more resistant to 0.025 mol/L NaOH comparing to the planktonic cells, while the biofilm cells in the VBNC state showed more endurance comparing to the planktonic cells under the same state. In conclusion, this study confirmed that in the brewing process, compared to the planktonic cells, the biofilm of P. damnosus could be more easily induced into VBNC state and had stronger tolerance to alkali under low pH, high concentration of bitter hops, ethanol and other pressure conditions.

Abstract:The differences of volatile specific aroma substances in kiwifruit wine of different ages were compared. This study provided new ideas to establish the identification methods of kiwifruit wine of different ages, and to further establish the quality evaluation of kiwifruit wine of different ages. Gas chromatography-ion mobility spectrometry (GC-IMS) was used to detect the volatile substances in kiwifruit wine of different ages, and to compare the changes in compositions. Principal Component Analysis (PCA) and "Nearest Neighbor" Fingerprint Analysis (NNFA) were used to analyze the differences of volatile substances. GC-IMS fingerprints showed that there were differences in the volatile substances in kiwifruit wine of different ages. There were 29 kinds of definite volatile compounds, including monomers and dimers of some substances. Furfural, 3-methylbutanal, ethyl 2-methylbutanoate and ethyl 3-methylbutyrate could be used as the specific volatile substances of five-year-old kiwifruit wine. Benzaldehyde could be used as the specific volatile substances of four-year-old kiwifruit wine. Butyl acetate, 2-methylpropyl acetate and acetic acid could be used as the specific volatile substances of three-year-old kiwifruit wine. The results of PCA and NNFA showed that the samples were well separated. The GC-IMS technology combined with cluster analysis could identify the differences of volatile substances in kiwifruit wine of different ages, providing ideas for the identification of kiwifruit wine of different ages

Abstract:To achieve rapid and efficient peeling of frozen grapes, the effects of infrared surface heating pretreatment combined with freezing on automatic peeling of grapes with different treated duration were explored. Two methods including infrared surface heating before freezing and infrared surface heating after freezing were applied in this study. The results showed that the infrared surface heating treatment for more than 5 minutes before freezing could cause obvious cracking of the grape peel, and the automatic peeling effect was obvious. However, the long-term infrared processing caused the decrease of grape hardness, color and other indicators. The short-term infrared treatment after freezing could better maintain the grape quality. The grapes were cracked without thawing could be ensured by 1 minute of infrared surface heating, therefore various methods could be used to automatically peel the grapes in the subsequent steps.

Abstract:In order to investigate and compare the similarities and differences of chemical composition of Rehmanniae radix, four-kind Rehmanniae radix (i.e., Radix rehmanniae, Radix rehmanniae preparata, Radix rehmanniae charcoal, and Radix rehmanniae preparata charcoal, shorted for RR, RRP, RRC and RRPC, respectively) were studied by infrared spectroscopy (FTIR) and their second derivative spectra were calculated. Their thermal performance changes during heat treatment were analyzed with a comprehensive thermal analyzer, and their surface chemical element content and microstructure were analyzed by X-ray energy spectrometer and scanning electron microscope (SEM). The results showed that four types of Rehmanniae radix had similar absorption peak position and shape, however, their absorption peak intensity was different. They all had absorption peaks of -OH, -CH, C=O and -NH of polysaccharides, alcohols and amino acid groups of Rehmanniae radix, among which the content of polysaccharide was higher in the dry root of Rehmanniae radix, while the absorption strength of RRC and RRPC significantly reduced in many peaks. The intensity and shape of second derivative of infrared spectra of four-kind Rehmanniae radix were quite different at the 1 200-500 cm-1 band. The four-kind Rehmanniae radix showed thermal weight loss due to the thermal decomposition of various polysaccharides, alcohols and amino acids under 190 ℃ ~ 350 ℃, and RR and RRP had significant thermal weight loss than that of RRC and RRPC. Compared with RR and RRP, RRC and RRPC had lower O element atomic content and higher C element atomic content were higher. These studies showed that the chemical composition was similar for four-kinds Rehmanniae radix, and RR and RRP had similar chemical composition and micro-structure, while RRC and RRPC had similar chemical composition and micro-structure. The content of polysaccharides and alcohols and amino acid in RRC and RRPC were significantly lower than that of RR and RRP.

Abstract:The effects of different drying methods on the structure and functional properties of Fritillaria thunbergii starch were studied. The bulbs of Fritillaria thunbergii were treated by vacuum freeze-drying, hot air drying and infrared hot air drying. The starch was extracted by enzyme. The basic components (moisture, protein, total starch, amylose and amylopectin) and physicochemical properties (solubility, swelling, freeze-thaw stability, transparency, sedimentation and aging value) were measured, and SEM, the particle size distribution of LS, FTIR, XRD and DSC were analyzed. The vacuum freeze-drying group had the highest starch content, the least damage to starch particles, and the strongest anticoagulation. The infrared hot air-drying group had the largest proportion of particle size volume and surface area, the lowest solubility, the highest coagulability and crystallinity, and the best freeze-thaw stability. There was insignificant difference in starch swelling and transparency among the three drying methods. Vacuum freeze-drying technology is more suitable for the utilization of starch resources and product development of Fritillaria thunbergii.

Abstract:In order to explore the mechanism of toxicity induced by citrinin in Monascus, the databases of Swiss Target Prediction, Similarity ensemble approach, Comparative Toxicogenomics Database and GeneCards were searched, and the software of Metascape, Kobas 3.0, Cytoscape 3.7.2 and AutoDock were employed for network pharmacology analysis. The results showed that a total of 110 potential targets, which showed the relationship between citrinin and liver toxicity as well as kidney toxicity, were achieved after filter and deduplication. There were 496 items enriched by GO analysis, including 97 molecular function, 354 biological process and 45 cell composition. The KEGG signal pathways with more enriched targets and higher significance mainly included MicroRNAs in cancer, Patyways in cancer, Hepatitis B and so on. Citrinin might induce hepatorenal toxicity through targets of TP53, CASP3, MAPK3 and ALB, and the molecular docking experiments showed that citrinin could bind to these targets. The potential targets and related signal pathways of citrinin-induced hepatorenal toxicity were revealed, providing theoretical reference for further study on the mechanism of citrinin-induced toxicity and health protection.

Abstract:The mechanism of metal antimicrobial peptide SIF4 against cell permeability of Staphylococcus aureus (S.aureus) was explored based on extracellular alkaline phosphatase activity (AKP), cell surface potential (CSP), cell surface hydrophobicity (CSH), cell inner membrane permeability (CIMP) and intracellular macromolecular leakage (IML). The results showed that SIF4 could destroy cell wall structural integrity. With the increasing of antibacterial peptide concentration and incubation time, the activity of extracellular AKP also increased simultaneously, and there was insignificant difference between 2MIC group and TritonX-100 group (P>0.05). The SIF4 concentration had a negative correlation with CSP, and a good dose-effect positive correlation with CSH. Moreover, CIMP and IML had a positive correlation with the antibacterial peptide concentration and incubation time. There was a significant difference in IML (P<0.05) after incubation for 1 h, while there was insignificant difference between the 2MIC and TritonX-100 groups(P>0.05) after 3 h incubation. The findings suggested that SIF4 could enhance cell permea- bility, cause IML leakage, enhance CSH and reduce CSP, inducing cell aggregation and apoptosis.

Abstract:The effects of selenium-enriched bacterium C5, Live Combined Bifidobacterium, Lactobacillus and Enterococcus Capsules, and Bacillus licheniformis Capsule on intestinal flora in mice were investigated. The mice were divided into the probiotics group A (Live Combined Bifidobacterium, Lactobacillus and Enterococcus Capsules group), the probiotics group B (Bacillus licheniformis Capsule + Live Combined Bifidobacterium, Lactobacillus and Enterococcus Capsules group), the experimental group C (selenium-enriched bacterium C5 group) and the blank group D. Mice feces were collected after 4 weeks of feeding. The V3-V4 region of 16S rDNA gene was amplified by PCR. Illumina Hiseq 2500 high-throughput sequencing was performed. The species abundance table at different taxonomic levels was generated by QIIME2 software, and the alpha-diversity index was evaluated and beta diversity was analyzed. Selenium-enriched bacterium C5 could regulate the abundance and diversity of intestinal flora in mice, which was comparable to the regulation produced by Live Combined Bifidobacterium, Lactobacillus and Enterococcus Capsules as well as Bacillus licheniformis Capsule. The alpha-diversity of ACE, Chao1 and Shannon were all increased (P＜0.05). Selenium-enriched bacterium C5 could increase the relative abundance of Firmicutes and Lactobacillus in the intestinal flora of mice, reduce the Staphylococcus and increase the relative abundance of Agathobacter in Lachnospiraceae(P＜0.05). Selenium-enriched bacterium C5 could improve the intestinal microecology of body and therefore it has certain application value in microbial agents to improve the health of intestinal flora.