Abstract:The quorum sensing system is a gene expression regulation system widely existing in a variety of microorganisms. It can realize the targeted regulation of related genes by the density perception of specific signal molecules, and exhibit different behaviors and characteristics in comparison with that in low density conditions, which helps to adapt the changes of environment. Due to the obvious biological universality, unique mechanism and high efficiency of quorum sensing regulation, it had become a research hotspot in the field of microbiology in recent years. As an important research object in food industry, microorganisms played important roles in research fields such as food preservation, probiotics production, food fermentation, green biosynthesis, microbial preservative and flavor agent production, etc. Therefore, to clarify the role of quorum sensing system in the above fields might be helpful to promote the further development of microorganisms in food production. This review focused on the main types of quorum sensing and the related regulatory mechanisms and summarized its important role in food spoilage and potential application in the future food industry. The future development of quorum sensing in food research was prospected, which might provide theoretical basis for the development of new food related technology based on quorum sensing.

Abstract:Probiotics are living microorganisms, and when consumed in sufficient quantities, they are beneficial to the host. Studies have found that breast milk contains living microorganisms, so probiotics for infants and young children are widely concerned. At present, there is no world widely clear and unified definition and consensus on “probiotics for infants and young children”. This paper described the types, common strains, safety and clinical research status of probiotics for infants and young children, and pointed out that the most studies focused on Lactobacillus and Bifidobacterium. Many reports showed that the safety of probiotics was good, but most function researches were from animal experiments, and there were few probiotics strains with mature and clear health function, especially lacking of sufficient clinical research.There were three challenges in the research and industry of infant probiotics:the contradiction between the new discovery of modern intestinal dominant flora and traditional probiotic strains, the lack of accurate mechanism analysis of health function in a deeper level like drugs, and the contradiction between the regulations of infant probiotics and clinical trial research of new strains. Although there were many problems,the incomplete gastrointestinal function and immune system of infants determined the bright prospect of probiotics development especially in China.

Abstract:The oral cavity is a complex and complete micro-ecosystem. Various factors such as lifestyle and pathogenshave adversely affected oral microbiome and perturbed the symbiosis between the microbiome and host, and this micro-ecological disorder could cause dental caries, periodontitis, gingivitis, halitosis and other oral diseases. Probiotics are living microorganisms that have beneficial effects on human body. Traditionally, probiotics have been widely used in various fields such as functional food, medicine, health care, and animal feed. The most common usages of probiotics are to treat or prevent gastrointestinal infections and diseases, and improve intestinal health. In the recent decade, probiotics was suggested to be used for oral health purposes due to positive improvement of various oral diseases via inhibiting the growth of pathogenic bacteria, improving oral microbial flora, regulating oral immunity, etc. In this review, we summarized the potential mechanism of oral probiotics in oral diseases, and described the important issues of using oral probiotics in the prevention and treatment of oral diseases, as well as the future development trends and development directions of oral probiotics. These insights might help build a theoretical basis for deep study of oral probiotics and improving its development and application in food industry.

Abstract:strains of lactic acid bacteria were isolated from mud of Baijiu and identified by 16S rDNA gene sequence homology analysis. There were 1 strain of Lactobacillus brevis, 1 strain of Lactobacillus rhamnosus, 2 strains of Lactobacillus casei and 7 strains of Enterococcus casseliflavus. Lactic acid production was analyzed using MRS medium fermented by 11 strains, respectively. And the results showed that lactic acid production was positively correlated with bacterial growth. The lactic acid yields of the strains Lactobacillus rhamnosus L₉, Lactobacillus casei L₁₀ and L₁₁ were relatively higher, which were 15.74,5.58,4.74g/L, respectively. The fermentated volatile flavor components from sorghum medium by each lactic acid bacteria were analyzed. There were 13 kinds of substances, including the important aroma components of Baijiu, such as acetic acid, caproic acid, phenylethyl acetate and phenylethyl alcohol. The relative content of acetic acid and caproic acid was relatively higher. The volatile flavor compounds produced by each bacterium were significantly different:Lactobacillus brevis L₅ could produce alkanes(27.91%), Enterococcus casseliflavus L₈ could produce alcohol compounds(43.14%), Lactobacillus rhamnosus L₉ produced esters(7.35%), ketones(3.61%) and pyrazines(3.3%), Lactobacillus casei L₁₁ had strong ability to produce acids(27.98%) and aromatic compounds(5.96%). Tetramethylpyrazine was produced by Lactobacillus brevis L₅ only, ethanol was obviously produced by strains of L₅ and L₈, and 3-hydroxy-2-butanone was produced by strains of L₉ and L₁₁. All the substances above strongly influenced the flavor and taste of Baijiu. Previous studies had shown that various lactic acid bacteria in the mud had different characteristics and effects on Baijiu brewing. This study provided a basis for further tapping the functional microbes of Baijiu brewing and expanded the application of lactic acid bacteria.

Abstract:Yellow water, the main by-product of Baijiu brewing, was rich in a variety of organic matter. It can be used to prepare esterification liquid, which can promote the aroma of Baijiu, and improve its utilization. Monascus sanguineus X1, a high esterifying enzyme-producing strain, was used to optimize the enzyme activity by single factor and orthogonal experiments from four aspects:carbon source, carbon-nitrogen ratio, inoculation amount and pH. Then, the esterifying solution was prepared by treating the yellow water with an esterifying enzyme solution, and the influence of the addition amount of the esterified precursors such as yellow water, ethanol and caproic acid on the preparation of the esterification liquid was studied. The results showed that the optimum fermentation medium for Monascus was (per 100mL) rice flour 7.0g, soybean peptone 2.0g, NaNO₃ 0.2g, KH₂PO₄ 0.15g, MgSO₄·7H₂O 0.1g, initial pH 5.0 and inoculation volume 10% (volume fraction). Under these conditions, adding 10% yellow water by volume and 4% ethanol by volume, the enzyme activity could reach 745.80U/mL. After adding 0.8% caproic acid and 20% ethanol by volume to the esterifying enzyme solution for 1 day, the volume fraction of ethyl caproate in the esterifying solution could reach 0.121%, while after adding 10% by volume yellow water to the esterifying enzyme solution, the volume fraction of ethyl caproate and ethyl lactate could reach 0.055% and 0.032%, respectively. The results is intended to provided a reference for the study of yellow water resources for Baijiu flavor enhancement.

Abstract:Oat, as a unique nutritional crop, is a new attempt for Huangjiu fermentation. In order to further explore the higher alcohols, microbial community structure and the correlations in oat Huangjiu, and study the characteristics of oat Huangjiu, the changes of higher alcohols during fermentation of oat Huangjiu were quantitatively analyzed by headspace solid phase micro-extraction and gas chromatography-mass spectrometry. And the alteration of microbial community structure during fermentation of oat Huangjiu was detected by high-throughput sequencing. The correlation between higher alcohols and microorganisms was predicted using statistical principles. Eighteen kinds of higher alcohols such as β-phenylethyl alcohol and 3-methyl-1-butanol were detected in oat Huangjiu. Firmicutes and Ascomycota were the highest relative abundant of bacterium and fungal on phylum level, respectively. Lactococcus and Saccharomyces were the highest relative abundant of bacterium and fungal on genus level, respectively. A total of 869 correlations were established between higher alcohols and microorganisms. Correlation analysis revealed that 297 genera might be involved in the metabolism of higher alcohols. Fermenting Huangjiu with oat not only increased the variety and raw material source of Huangjiu, but also improved the nutritional value of Huangjiu. In addition, the correlation analysis between higher alcohols and microorganism predicted the biological mechanism of quality characteristics of oat Huangjiu.

Abstract:In this experiment, the effects of Gastrodin elata extract, Fagopyrum tataricum extract and their mixtures on the growth and extracellular polysaccharide synthesis of Grifola frondosa were studied. The dynamic changes of residual sugar (reducing sugar) content and pH value in the fermentation system after adding the compound solution were also detected. The results showed that the best effect was observed after addition of Gastrodin elata extract and Fagopyrum tataricum extract at concentrations of 7g/L and 5g/L, respectively. Compared with the blank group (without adding extract) and the single addition group(Gastrodin elata or Fagopyrum tataricum), the yield of extracellular polysaccharide in compounding group was increased by 49.08%, 13.76% and 33.88%, respectively,and the mycelial biomass was increased by 51.10%, 11.35% and 26.69%, respectively, which were significantly higher than those in the blank group (P<0.01) and the single addition group(P<0.05).Fermentation kinetics analysis showed that the growth of Grifola frondosa and the production of extracellular polysaccharides peaked on the 7th day, and the compounding group could consume more carbohydrate than the blank group to promote the synthesis of extracellular polysaccharides. Therefore, the active ingredients in Gastrodia elata and Fagopyrum tataricum can significantly promote the growth of Grifola frondosa and the synthesis of extracellular polysaccharides.

Abstract:Bacillus natto can convert sodium selenite into organic selenium. The growth curve of a strain of Bacillus natto was measured, and the optimum time and addition amounts of sodium selenite were determined. Using B.natto BSN424 as original strain, based on screening of Se-tolerance and Se-enri-ching, a genetic stable mutant strain BN-44 was obtained by atmospheric and room temperature plasma mutagenesis system. The results showed that the optimum time for selenium addition was at the 3rd hour in the culture period, and then the culture was continued to 24 hours. The optimum mass concentration of selenium in culture medium was 6μg/mL. The power of atmospheric and room temperature plasma mutagenesis system was 100W and the mutagenic time was 25s. After mutagenization, the BN-44 was eventually selected as the best strain with a high selenium content. Compared to the original strain, the selenium content after shaking and fermentation by BN-44 was increased from 742.12μg/g to 1136.43μg/g, which was increased by 53.13%. The results had shown that the atmospheric and room temperature plasma mutagenesis breeding method could mutagenize Bacillus natto BSN424 effectively, which provided a basis for the search of Se-enriching probiotic vector and its mutation breeding in organic selenium biotransformation.

Abstract:Proanthocyanidins (PC) with high anti-oxidative activity are broad categories of polyphenol compounds that widely exist in plants and are widely used in food, medicine and other fields. However, PC has low bioavailability due to its poor stability, and improving its stability will help expand its application range.A kind of monodisperse mesoporous silica nanoparticles (MSNs) was prepared by aerosol method using tetraethoxysilane (TEOS) as silica precursor and cetyl and trimethyl ammonium bromide (CTAB) as template. PC was subsequently loaded into MSNs to prepare PC-MSNs complexes using dipping method, and the loading effects of temperature, PC mass fraction, processing time, and MSNs addition amount were examined. The release of PC-MSNs was studied by simulating the gastrointestinal tract (GIT) conditions. The results showed that the most suitable conditions were as follows:MSNs addition amount was 5mg/mL, PC mass fraction was 4mg/mL, and the alternating treatment program of variable temperature was 30℃ for 0.5h, then 4℃ for 0.5h and repeated this process twice. In this condition, the loading mass was highest, and MSNs loading capacity was 512mg/g.According to Brunauer-Emmett-Teller (BET) analysis method, specific surface area and pore volume were decreased significantly, indicating that PC was successfully loaded into MSNs particles.Unloaded PC only retained 50.2% at the end of intestinal digestion, while loading PC on MSNs system could prevent it from damage by gastric acid and successfully arrived in small intestine. There was 77.1% PC retained at the end of intestinal digestion, indicating that MSNs could significantly increase the PC mass in small intestinal juice and improve its bioavailability.

Abstract:The present study aimed to investigate the anti-aging effect of black rice anthocyanin (BRA) on Drosophila melanogaster and its underlying mechanism. Two-day-old wild Drosophila melanogaster were fed with different concentrations of BRA (0,1, 5mg/mL). Longevity test, gustatory assay and climbing assay were carried out to detect the effects of BRA on the life span and health span of fruit flies. The effects of BRA on intestinal integrity of Drosophila melanogaster were analyzed by Smurf assay. The mRNA expression of antioxidant-related genes, namely SOD, CAT and Rpn11, were measured by real time-PCR. BRA prolonged the life span and health span of fruit flies compared with those in control group, which also had a protective effect on intestinal integrity of fruit flies. The mRNA expression level of antioxidant-related genes were significantly increased (Cu/Zn-SOD, P<0.01; Mn-SOD, CAT and Rpn11, P<0.05).The anti-aging and antioxidant effects of BRA might be achieved by up-regulating endogenous antioxidant genes.

Abstract:In this study, the activity of amylase was measured to discuss whether Nippon hawthorn (Crataegus cuneata) and Chinese hawthorn (Crataegus pinnatifida) could promote digestion by improving the activity of amylase. After the preparation of hawthorn extracts at different temperatures (30,0, 80℃), the intestinal environment was simulated and the effects of hawthorn water extracts on amylase were investigated at different reaction temperatures (25,7, 45℃), different pH (6.5,6.8), and ion conditions (C₂O2-₄, Zn²⁺). The results demonstrated that the activity of amylase could be increased by hawthorn extracts at each reaction temperature and pH. Among them, the extracts from Chinese hawthorn under 60℃ showed the strongest promoting effect on activity of amylase under the reaction conditions of 37℃ and pH 6.5. C₂O2-₄ had the promoting effect on the reaction of amylase with the Chinese hawthorn, while Zn²⁺ showed the inhibitory effect of extracts from Nippon hawthorn and Chinese hawthorn on promotion of amylase activity.

Abstract:Fresh sirloin beef was taken as research object, after vacuum packaging, it was heated to center temperature at 60℃ (lasting 28-32min) , 65℃ (lasting 46-50min) , 70℃ (lasting 60-65min) and 75℃ (lasting 82-86min) in water bath. And the control group was heated to 100℃ (lasting 165-170min). The quality indicators such as tenderness, water retention, pH, color, protein, fat and moisture of each beef sample were measured, and the quality evaluation model of beef with sous vide cooking was constructed using principal component analysis (PCA). The results showed that the pH, color and moisture content of beef were significantly affected by heating temperature (P<0.05). Tenderness, water retention and color intensity of beef heated at 65℃ were optimal for shearing force of 12.82N, water retention of 86.71%, color intensity of 7.33. The characteristic roots of the first, second and third principal components were greater than 1 by PCA method, and the cumulative contribution rate reached 96.514%, which could better reflect the original information of beef quality index. According to the model, the order of heating temperature corresponding to quality of beef with sous vide cooking were as follows:65,0,70,5,100℃, having a good agreement and significant positive correlation with fuzzy mathematical sensory scores (P<0.01), which further confirmed the objective reliability of this model.

Abstract:The ultrasound-assisted extraction process of polysaccharides from the bee pollen of wolfberry was optimized by response surface methodology based on Box-Behnken design with the extraction rate as the observation indexes. The antioxidant activity of polysaccharides extracted by the optimal process was studied in vitro. The optimal extraction conditions were obtained as follows:solid-liquid ratio 1∶25 (g/mL), temperature 90℃, ultrasonic power 240W, and ultrasonic time 20min. Under these conditions, the yield of polysaccharides was 0.89%-0.91%, which was insistent with the predicted value, and it indicated that the model was good and the optimization process was feasible. The results of antioxidant activity in vitro were showed that the polysaccharide extracted from bee pollen of wolfberry had good DPPH radicals and ABTS⁺· scavenging activities, however, the FRAP value was low. The results provided a basis for the research, development, and utilization of polysaccharide extracted from bee pollen of wolfberry.

Abstract:In order to shorten the reaction time and improve the stability of Channa argus short peptide-zinc (CASP-Zn), the ultrasonic technology was employed to analyze the effects of different time (0,5, 10,5, 30,5, 60,5, 90,0min) and different ultrasonic power (0,0, 240,0, 480W) on the chelating rate, spectral structure, microstructure and antioxidant activity of CASP-Zn. The results showed that the ultrasonic treatment significantly affected the chelating rate of CASP-Zn , and the chelating rate of CASP-Zn was the strongest and around 93.0% after ultrasonic treatment with the power of 360W. In a short time (15min), the chelating rate of CASP-Zn after ultrasonic treatment with different power reached a higher value. Compared with other ultrasonic treatment groups, the maximum UV-VIS absorption peak and fluorescence spectrum intensity of CASP-Zn treated with the power of 360W were the highest. Scanning electron micrograph analysis showed that the ultrasonic treatment group of 360W had the closest combination. CASP-Zn also had certain antioxidant activity. Among them, CASP-Zn treated with different ultrasonic power had no significant influence on superoxide anion free radical and H₂O₂ scavenging rate, while CASP-Zn after ultrasonic treatment with power of 360W had a strong DPPH free radical scavenging rate. It showed that the antioxidant activity was positively correlated with the stability of chelate complex. Ultrasonic technology could promote the chelation reaction and enhance the stability and antioxidant activity of peptide-zinc complex.

Abstract:Using regular brown rice, red rice and black rice as raw material, the radial expansion rate, water soluble index, water absorption index, dispersion time, agglomerate rate,paste viscosity, gelatinization degree, reducing sugar and protein contents of brown rice flour produced by thermostable α-amylase assisted extrusion treatment was measured. The results showed that after thermostable α-amylase assisted extrusion treatment, the radial expansion rate and gelatinization degree in three types of whole brown rice were reduced significantly(P<0.05). The water soluble index was increased(P<0.05) by 2.51 times, 1.89 times and 2.73 times, respectively. And the water absorbent index was decreased significantly(P<0.05) by 77.29%, 33.41% and 67.44%.The dispersion time and agglomeration rate were also reduced significantly(P<0.05). The dispersion time was reduced by 64.60%, 60.66% and 65.40%, respectively. The agglomeration rate was reduced by 75.57%, 84.64% and 75.24%. The dissoving viscosity decreased significantly(P<0.05). The whole brown rice flour treated with enzyme had lower viscosity at low shear rate, and its viscosity curve tended to be straight. The content of reducing sugar and soluble protein was increased significantly(P<0.05), while the content of total protein had on obvious change(P>0.05).

Abstract:Microbial food cultures (MFC) usually used as starter cultures or food raw materials(also known as probiotics) plays highly significant roles in food industry. In order to establish standardization for MFC management, especially to ensure the safety of MFC used in food,different countries and regions have developed various management models based on their unique conditions and management system characteristics.The standards and regulations of MFC in China were summarized. Different management agencies, their responsibilities and extent of competence, distinguishing features of management models, as well as contents, procedures and requirements on risk assessment were elaborated and analyzed respectively through horizontal comparison of management regulations in European Union, United States of America, Australia, New Zealand, Canada, etc. Based on the administration situation of MFC management in China, the definition and management of “novel MFC”and characteristics of specific management measures such as general requirements for safety assessment in different international organizations, countries and regions were compared.The system of MFC management had been established but still faced many challenges in China. In order to provide references for the improvement of management model and promote management efficiency, the advices encountered in the MFC management were put forward, including suggestions of improving requirements for risk assessment, establishing a post-market follow-up evaluation mechanism, and improving food labeling standards.