This study investigated the membrane injury of Escherichia coli O157:H7 cells exposed to high hydrostatic pressure. Different pressure levels (200, 400 and 500 MPa) were used to evaluate the inactivation of the bacteria. The leakage of nucleic acids, K+ and Mg2+, and propidium iodide (PI) intake of the cells, as well as changes in Na+/K+-ATPase and Ca2+/Mg2+-ATPase activities were determined after pressure treatment. Results indicated that, after 200 and 400 MPa treatments for 5 min, the number of viable cells decreased from an initial level of 8.8 to 8.2 and 6.3 (lg(CFU/mL)), respectively. When treated at 500 MPa, no viable cells were detected on plate count agar. As the pressure level rose, the leakage of intratracellular constituents and the fluorescence (OD) of PI intake increased significantly and both enzyme activities significantly decreased. Ca2+/Mg2+-ATPase was more sensitive to pressure than Na+/K+-ATPase, and the enzyme activities were almost completely inactivated after pressurization at 500 MPa. High pressure treatment caused obvious damage to the membrane of E. coli O157:H7 cells. The major cause of E. coli O157:H7 death after high hydrostatic pressure treatment was the inactivation of Ca2+/Mg2+-ATPase.

The production of bacteriocin by Enterococcus faecium TRS5 was found to be maximum at 37 ℃ and pH 6.5 after 24 h of incubation in MRS broth. The presence of tryptone or glucose in the medium stimulated the bacteriocin production. Added maltose, lactose or mannose (20 g/L) resulted in a 50% reduction of bacteriocin activity. High levels of glycerol and Tween-80 (5 g/L) also repressed the bacteriocin production. The presence of K2HPO4 or vitamins VB1, VB2, VB6, or VC in the medium had no effect on the bacteriocin production. E. faecalis TRS5 was sensitive to erythromycin, chloramphenicol, vancomycin, teicoplanin, tetracycline and penicillin G. PCR amplification and sequencing demonstrated that E. faecalis TRS5 harbored enterocin P and L50-like structural genes.

Candida versatilis (called T yeast) and Zygosaccharomyces rouxii (called S yeast) are often used as starter cultures to enhance the flavor quality of high-salt liquid-state soy sauce. However, there are currently no auxotrophic strains available for the genetic manipulation of S yeast and T yeast. Therefore, ethylmethane sulfonate (EMS) and ultraviolet (UV) irradiation were used to mutagenize the yeasts obtain uracil auxotrophic strains. On the basis of mortality rate, the optimal concentration of EMS, EMS treatment time, UV irradiation distance, UV irradiation time, and yeast concentration were determined. In the end, the uracil auxotrophic strains were screened out and identified by gene sequencing, which will lay the foundation for molecular biology studies of salt tolerant yeast.

Crude flavonoid 3’-hydroxylase (F3’H) from fresh-cut Chinese water chestnut was extracted by Tris-HCl buffer (pH 7.5), and then isolated and purified successively by ammonium sulfate precipitation, dialysis, DEAE-cellulose ionexchange column chromatography and Sephardi G-100 gel filtration chromatography. After purification, the enzyme was finally purified 14.01 folds with a specific activity of 478.49 U/mg and a protein yield of 6.38%. The purified enzyme showed a single protein band with a molecular mass of about 53.09 kD as estimated via sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Further enzymatic characterization showed that the purified enzyme activity attained its maximal value at 30 ℃ and pH 7.5, and had a Km and vmax of 1.08 mmol/L and 416.67 U/(min·mL), respectively, using naringein as the substrate. The flavonoid 3′-hydroxylase activity was slightly inhibited by Ca2+ and citric acid and strongly inhibited by Na+. However, Fe2+, Mg2+, NADPH and ascorbic acid strongly activated its activity.

The antimicrobial peptide produced by Brevibacillus laterosporus shows efficient, broad-spectrum, and stable antimicrobial activities, which are closely associated with the endogenous plasmid in B. laterosporus S62-9. In order to study the feasibility of heterologous expression of B. laterosporus plasmid with antimicrobial peptide genes, B. laterosporus S62-9 plasmid was transferred into Bacillus subtilis Wb800 by electroporation. The positive transformants were screened and the expression products were characterized. The results showed that strain Z4 showed an antimicrobial activity after fermentation for 6 h, reaching the highest titer (620.96 AU/mL) during 12–20 h. Tricine-SDS-PAGE indicated that B. laterosporus plasmid was successfully expressed in B. subtilis. Reversed-phase high performance liquid chromatography (RP-HPLC) analysis showed that the expression products of strain Z4 and B. laterosporus antimicrobial peptide contained the same substances, which showed broad-spectrum antimicrobial activities with high stability. Both of them displayed strong antimicrobial activities against Gram-positive bacteria, Gram-negative bacteria and fungi, especially against Gram-positive bacteria. About 90% and 81% of the titer was retained after 20 min at 121 ℃ and after 60 min at 100 ℃, respectively. The antimicrobial activity showed a slight change in the pH range of 2–12. However, the antimicrobial peptide was more sensitive to proteases and the titer was reduced by about 40% after treatment with trypsin or proteinase K, and was also reduced after treatment with three other proteases. The establishment of strain Z4 may lay a foundation for the industrial production of antimicrobial peptide in the future, and provide evidence for positioning the B. laterosporus antimicrobial peptide gene on plasmid.

To find a new cheap and easily available source of tyrosinase and to provide an experimental basis for further research on inhibitors of tyrosinase from lettuce tip, electrophoretically pure tyrosinase was obtained from Yunnan-grown lettuce tip through consecutive homogenization, buffer extraction, ammonium sulfate fractionation, DEAE-Sepharose fast flow chromatography and Superdex-200 prep grade chromatography. The results showed that the specificity activity of the purified enzyme was 20.62 U/mg. The relative molecular weight of the tyrosinase was approximately 995.40 kD, in which the subunit molecular mass was roughly 65.23 kD. The enzymatic properties showed that the optimum temperature and pH for the tyrosinase were 60 ℃ and 8.0, respectively. The enzyme was stable in the pH range of 6.0–8.0 and in the temperature range of 20–40 ℃. Its apparent Km and vmax were 1.567 mmol/L and 0.037 6 μmol/(min·L), respectively. The tyrosinase activity was slightly affected by EDTA, urea, K+, Mg2+and Li+. The enzyme activity could be inhibited by ethanol, isopropanol, n-butanol, but activated by methanol, Co2+, Mn2+, Pb2+, Ag+, Cd2+, Ba2+, and Ca2+, and it could be obviously activated by Co2+, Mn2+. Ascorbic acid, Zn2+, Cu2+, and oxalic acid enhanced the enzyme activity at low concentrations but inhibited it at high concentrations.

In this study, the archaeal community structure in pit mud from cellars of different ages used for the production of Luzhou-flavor liquor was researched by high-throughput sequencing technology. The diversity of archaeal community was analyzed and cluster analysis of pit mud with different cellar ages was performed based on the obtained data. Also, we investigated the effect of environmental factors on the archaeal community structure of pit mud with different cellar ages. The results were obtained as follows. The main archaeal phylum in the pit mud samples was Euryarchaeota (99% of OTU), consisting of 7 genera. The diversity of archaeal community showed a decreasing trend with increasing age of pit mud. Similarly, the dominance of Methanobacterium and Methanocorpusculum showed a decreasing trend with increasing age of pit mud, contrary to Thermoplasmatales. Similarity of archaeal community structure between pit mud from 5-year-old cellars and pit mud from 100-year-old cellars was higher, while the diversity of archaeal community in pit mud from 30-year-old cellars was higher. The environmental factors with the greatest effect on the archaeal community structure of pit mud from different aged cellars were different. In summary, the archaeal community structure in pit mud with different cellar ages showed a significant difference, which might be part of what causes the different qualities of Luzhou-flavor liquor produced from pit mud with different cellar ages.

This study aimed to develop a new functional product by fermenting sea cucumber ovum, a by-product of sea cucumber processing, with Bacillus natto. Fibrinolysin (FIB) activity was measured as an index to optimize the fermentation condition. Results showed that the optimum carbon source was glucose at a concentration of 2%. The optimized results of other fermentation parameters were as follows: initial pH, 7; inoculum amount, 5%; fermentation temperature, 37 ℃; medium loading volume, 20%; solid-to-liquid ratio, 1:30 (g/mL); and rotational speed, 180 r/min. The fermentation supernatant, collected after centrifugation at 7 000 r/min for 20 min, demonstrated FIB activity as high as 6 723 FU/mL and ACE inhibition activity with a high inhibition percentage of 90% at a final protein concentration of 20 mg/mL. The time required for partial activation of thromboplastin and the thrombin time were significantly extended by the supernatant when the protein level was 5–20 mg/mL, and it also decreased FIB content while having no influence on prothrombin time. Furthermore, some proteases in the supernatant were observed by zymography. Therefore, the fermentation product of sea cucumber ovum showed relatively strong thrombolytic, antihypertensive and anticoagulation activities, demonstrating a potential auxiliary therapeutic agent for cardiovascular disease. Hence, it deserved further development.

Five different kinds of Fu tea were produced from oolong tea (Dahongpao), black tea, green tea, and tea leaves used for making two kinds of dark tea, Tianjian tea and Jinxiangyi brick tea, by fungal fermentation in a loose state. ‘Golden Floral’ fungi isolated from these Fu teas showed morphological differences. Further differences were investigated by microbiological methods. The isolated fungi were systematically identified by morphology and DNA sequence analysis. Meanwhile, the aflatoxin producing ability of these isolates was determined by high performance liquid chromatography (HPLC)-triple quadrupole tandem mass spectrometry. The results revealed that all the ‘Golden Floral’ fungi isolated were assigned to the same species and they were not different from the initial inoculum, which were classified as Eurotium cristatum in the Eumycota genus in the Eurotiaceae family in the Eurotiales order in the Euascomycetes subclass in the Ascomycetes class in the Eumycota phylum and its anamorph was identified as Aspergillus spiculosus Blaser. And the mass spectral data showed that AFB1, AFB2, AFG1 and AFG2 were not detected, indicating that the ‘Golden Floral’ fungi are not able to produce aflatoxins.

An anaerobic Clostridium strain designated HBUT-01was screened from river sludge. By 16S rDNA sequence analysis, the strain was identified as Clostridium butyricum and its 16S rDNA fragment shared 99% similarity with that of C. butyricum DSM 10702T (AQQF01000149). The response surface methodology (RSM) was used to optimize the fermentation medium for this isolated strain, and a quadratic regression model with yeast exact, CaCO3 and glucose as independent variables was established by Design-Expert 8.0 software. The optimum medium was determined as follows: glucose 1.60%, yeast extract 0.72%, peptone 2.50%, CaCO3 0.43%, K2HPO4 0.05%, MgSO4·7H2O 0.08%, and MnSO4·H2O 0.002%. Batch cultures were carried out in a 10-L bioreactor, and an increase in specific productivity of butyrate (qp) of 20% and an increase in biomass yield coefficient (Yx/s) of 132% were obtained as compared with that before optimization. The results suggested that the impact of acid stress on the cells was relieved effectively and cell activity was also maintained with the optimized medium, which resulted in an increased biomass, reaching 9.32×108 CFU/mL at 14 h, which was increased by 2.24 times as compared to that with the basic medium.

This study aimed to prepare a highly specific monoclonal antibody (mAb) against Vibrio parahaemolyticus for the purpose of solving the constraints on the development of immunological assays for this pathogenic microorganism. We injected Balb/c mice with V. parahaemolyticus ATCC 17802. The hybridoma cell line 3F7D7E8C4, which could stably secret mAb against ATCC 17802, was obtained after cell fusion and screening by indirect ELISA. By using a commercial kit, the mAb was identified to belong to the IgG1 subclass. The antibody titer of the ascites was 1:16 000. After purification with saturated ammonium sulfate precipitation and protein G affinity chromatography and purity analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), the titer of the antibody was 1:8 000 and the sensitivity (IC50) was 106 CFU/mL. The purified antibody could specifically bind to 12 V. parahaemolyticus strains, and had no cross-reaction with 9 non-V. parahaemolyticus foodborne pathogens.

An engineered strain producing high β-glucosidase activity was constructed and applied in the production of 2,6-dimethoxybenzoquinone. The β-glucosidase gene was amplified from the genomic DNA of Saccharomyces cerevisiae CS1401 using PCR. The amplified gene was then ligated to pPICZαA vector and transformed to Pichia pastoris X33 for expression under the induction of methanol. The activity of the recombinant enzyme was measured, and S. cerevisiae CS1401 and the recombinant strain were separately cultured in wheat germ medium for the production of 2,6-dimethoxybenzoquinone. The results indicated that the β-glucosidase gene of S. cerevisiae CS1401 was efficiently expressed in the engineered strain of P. pastoris X33, giving a β-glucosidase activity of up to 4.5 U/mL, which was 5 times higher than that of S. cerevisiae CS1401. Besides, the yield of 2,6-dimethoxybenzoquinone produced by the recombinant strain in shaking flasks reached 935.7 μg/g, which was 40% higher than that of S. cerevisiae CS1401. Therefore, this engineered strain has a promising prospect of application in the microbial production of 2,6-dimethoxybenzoquinone.

Lactic acid bacteria (LAB) were isolated from the intestine of 10 common kinds of marine animals collected from the South China Sea by the pour plate method. The antimicrobial activity of the LAB isolates was determined by Oxford cup diffusion method against five pathogenic indicator strains including E. coli, V. parahaemolytics, S. aureus, B. subtilis, and L. monocytogenes. The diversity analysis of these LAB strains was conducted by establishing phylogenetic tree based on 16S rRNA gene sequences. The results showed that 43 isolates, which presented soluble calcium circle and were positive by Gram staining and negative in catalase reaction, were identified as LAB according to morphological observation and partial physiological and biochemical experiments, and they all possessed antimicrobial activity in different degrees. Out of these, 13 strains were found to have stronger bacteriostatic ability and a wider antimicrobial spectrum, and they were further identified based on phyogenetical analysis of 16S rRNA sequence. The results indicated that they belonged to 6 genera in 4 families of Firmicutes. Although strain LY-87 and the type strain of Lactococcus lactis subsp. lactis shared 100% 16S rRNA gene sequence similarity, there were genetic differences between other LAB strains and the typical strains showing the closest phylogenetic relationship with them (similarity ranging from 95.7% to 99.9%). The similarity between strain PQ- 26 and the type strain of Pediococcus pentosaceus was only 95.7% suggesting that it is likely to be a potential new species of Pediococcus. This research indicates that LAB with antimicrobial activity are diverse and there may exist potential new species in the intestine of animals from the South China Sea in Zhanjiang. The antimicrobial substances produced by these bacteria need to be further studied and developed.

Ternary mixed starter cultures of Lactobacillus plantarum, L. rhamnosus, L. acidophilus and L. casei were used for the fermentation of germinated brown rice milk. The best starter culture was determined by evaluating acidity, viable cell count, syneresis susceptibility, proteolytic activity and rheological property after culture at 4 ℃ for 21 days. The results showed that germinated brown rice milk fermented by a starter culture consisting of L. plantarum, L. acidophilus and L. casei displayed good quality, and exhibited weak post-acidification during the subsequent 21 days of storage at 4 ℃, with the pH being reduced by only 0.71. Additionally, the viable cell count changed somewhat during the refrigerated storage, remaining higher than 8.7 (lg(CFU/mL)), and the average content of free amino acids was up to 0.86 mmol/L. The rheological measurement indicated that its shear thinning behavior was weaker. In consequence, the co-culture of L. plantarum, L. acidophilus and L. casei was suitable for the fermentation of germinated brown rice milk.

In order to investigate the relationship between the diversity of the bacterial community in solid-fermented fish products and their quality, bacterial numbers in four samples of traditional fermented fish produced by different procedures were examined by conventional count methods, and the structure and composition of the bacterial community were investigated by 16S DNA V4 region sequence and phylogenetic relationship analysis using Illumina HiSeq sequencing platform. Meanwhile, these samples were subjected to sensory evaluation and GC-MS analysis. The results obtained were as follows. The average number of sequences obtained from the sample was 59 250. A total of 1 053, 392, 428 and 498 operational taxonomic units (OTU) were observed for the samples zyA2, zyA5, zyB and zyC, respectively. The overall bacterial composition of the four samples was rather complicated, including more than 30 genera in 11 phyla，among which, Firmicutes was absolutely dominant, accounting for 66.25%–97.40% of the total number, followed by Proteobacteria and Bacteroides, and the main dominant genera were Staphylococcus, Enterococcus, Lactobacillus and Weissella. Compared to traditional methods, the information about bacterial community diversity provided by MiSeq sequencing was closer to the microflora in the samples. 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. The species and quantity of bacteria also affected the color and flavor of the product. In addition, we also detected a small amount of potentially harmful spoilage organisms like Pseudoalteromonas, Tenacibaculum, Corynebacterium and Psychrobacter and conditional pathogens in the samples. Therefore, the processing conditions must be strictly controlled under the existing mode of production to avoid food safety problems.

Vibrio harveyi is a main pathogenic bacterium that can induce vibriosis of shrimp and fish in the marine environment, causing huge economic losses in aquaculture. In this paper, 49 strains of lactic acid bacteria (LAB) were isolated from the marine fish intestine by the use of 1.0% CaCO3 MRS agar, including seabass, coilia ectenes, Paralichthys lethostigma and turbot. strain YP4-5 isolated from the intestine of Paralichthys lethostigma had strong antagonistic activity against V. harveyi using the method of Oxford cup agar diffusion, showing an inhibitory zone diameter of 18.26 mm. Antimicrobial substances of the cell-free supernatant (CFS) produced by strain YP4-5 were sensitive to protease, heat stable and effective within the pH range of 2.5–4.5, and they were preliminary determined as bacteriocins. The growth curve indicated that 74.74% of V. harveyi was inhibited by treatment with the CFS at a concentration of 0.4 MIC. Furthermore, cell integrity damage, cell membrane dissolution and intracellular component leakage were observed by scanning electron microscope. Strain YP4-5 was identified as Lactobacillus sakei according to physiological and biochemical characteristics and 16S rRNA sequence analysis. This research can provide a good source of probiotics to prevent and control V. harveyi infection in aquaculture.

Objective: To explore the structure and function of the five lactate dehydrogenase genes and their encoded proteins from Lactobacillus plantarum LY-78. Methods: Several bioinformatic tools were used to analyze and predict the gene sequences and amino acid sequences of lactate dehydrogenase from the strain. Results: The nucleotide and amino acid sequences of the five lactate dehydrogenases in L. plantarum LY-78 were all highly conserved. The five lactate dehydrogenase proteins showed thermal stability and were non-secretory and non-transmembrane proteins, which were located in the cytoplasm. All the four genes except ldhL3 had highly conserved functional sites and domains, and contained the highly conserved sequence GXGXXG, which had typical NAD+ binding sites. Conclusion: D1-LDH, D2-LDH, L1-LDH and L2-LDH manifest complete functional sites and domains, likely having a real activity of lactate dehydrogenase. Because of the lack of NAD+ binding domain and functional sites, L3-LDH may not have lactate dehydrogenase activity. These results are important for theoretical researches of genetic modification of the lactate dehydrogenase genes and the metabolic mechanism of phenyllactic acid in L. plantarum LY-78.

In this study, lactic acid bacteria (LAB) were isolated, purified and identified from naturally fermented northeast sauerkraut juice and used to develop a new fermented dried venison product with both good flavor and nutritional quality. We analyzed the fermentation characteristics of the LAB isolate and Debaryomyces hansendii, and we also used starter cultures consisting of mixtures of the two strains to ferment venison pieces and evaluated their fermentation characteristics. Optimization of the fermentation conditions was performed by the combined use of one-factor-at-a-time method, Plackett- Burman design and response surface methodology. The results showed that fermentation time, fermentation temperature and inoculum size had significant impacts on the fermentation characteristics of venison. The fermentation of venison by both strains rapidly produced sour substances, and favored the formation of flavor-active substances so that they were suitable to be used as starter cultures to produce fermented dried venison. A quadratic regression equation for the pH and sensory evaluation score of fermented venison was established as a function of fermentation time, fermentation temperature and inoculum size, respectively. The fermented dried venison had the highest sensory score and an average pH of 5.07 after 20.86 h fermentation time at 27.51 ℃ with an inoculum size of 2.16 mL/100 g.

themostable pullulanase-producing strain, designated as T-10, with enzymatic activity of 1.22 U/mL, was isolated from soil samples collected at a crater field. By applying morphological observation, physiological and biochemical tests and 16S rDNA sequence homology analysis, it was identified as Bacillus amyloliquefacienss. The optimum temperature for the pullulanase activity was 60 ℃ and more than 60% of its maximum activity was maintained after incubation at 70 ℃ for 4 h. The optimum pH value for the pullulanase activity was 6.0, and about 70% of its maximum activity was maintained in the range of 3.0?8.0 after incubation for 4 h. At present, only a few thermostable pullulanase-producing strains of B. amyloliquefaciens are available, and so this new strain of B. amyloliquefaciens has a good application prospect.

The contents of total phenolics (TPC) and total flavonoids (TFC) and antioxidant activities (1,1-diphenyl-2- picrylhydrazyl (DPPH) radical scavenging activity, reducing power and total antioxidant capacity) in different solvent extracts from Cyclocarya paliurus leaves (CPL) obtained with water, 70% ethanol, ethyl acetate and n-hexane were determined by the 96-well plate method. The correlation between phenolics contents and antioxidant activities was investigated and the main bioactive constituents were identified by using ultra performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UPLC-QTOF-MS/MS). There were significant differences in the contents of total phenolics and total flavonoids and antioxidant activities among different extracts. The 70% ethanol extract showed the highest contents of total phenolics (219.01 mg GAE/g) and total flavonoids (7.23 mg CE/g), and the strongest DPPH radical scavenging activity (35.46 mg TE/g) and reducing power (1.89 mmol FeSO4/g). Each bioactive component demonstrated positive correlations with DPPH radical scavenging ability and reducing power and negative correlations with total antioxidant capacity, indicating that polyphenols mainly account for the antioxidant activities of CPL extracts. The 70% ethanol extract was analyzed by UPLC-QTOF-MS/MS, and a total of 22 compounds, including 2 organic acids, 4 phenolic acids, 5 flavonoids, 8 triterpenoid saponins and 3 esters, were identified, among which, phenolic acids and flavonoids were the major antioxidant constituents, while organic acids, triterpenoid saponins and esters might be potential antioxidant components.

Maillard reaction products (MRPs) were prepared from a complex reaction system containing cysteine, xylose, and glycine under different initial pH values (4.5?7.5) and investigated for the measurement of absorbance at 420 nm and the final pH values, and the analysis of volatile compounds by solid phase micro extraction (SPME) and gas chromatographymass spectrometry (GC-MS). It turned out that the greater the initial pH value was, the greater the degree of browning was and the more significantly the final pH values decreased. The most predominant flavor compounds identified were sulfur-containing compounds, followed by nitrogen-containing heterocyclic compounds and oxygen-containing heterocyclic compounds. The abundant sulfur-containing compounds were 2-methyl-3-furanthiol, 3-mercapto-2-pentanone, 2-furfurylthiol, 2-thiophenethiol, and bis(2-methyl-3-furyl) disulfide, 2-methylthiophene, and 2-acetylthiazole. With the increase in initial pH value, both the total content of volatile compounds and the content of sulfur-containing compounds identified firstly increased and then decreased, reaching a peak at pH 5.5. However, the content of nitrogen-containing heterocyclic compounds increased gradually, and the content of oxygen-containing heterocyclic compounds decreased. Further, the MRPs from reaction at 90 ℃ for 1 h at an initial pH of 4.5 or 7.5 were analyzed by high performance liquid chromatography with evaporated light scattering detection (HPLC-ELSD) and liquid chromatography-mass spectrometry (LC-MS). It was concluded that the pathway to develop volatile flavors at an acidic initial pH differed from that under a basic initial pH. For the former, the pathway involved cysteine-Amadori degradation, while for the latter it involved both cysteine-Amadori degradation and the reaction of glycine-Amadori with cysteine. Since at a basic initial pH, the compounds with an amino group (such as amino acids, and ammonia) were more active, the Maillard reaction became faster, which led to greater amount of cysteine-Amadoris intermediates during the early stage of the reaction and consequently the generation of more melanoidins and pyrazine compounds during the middle and late stages of the reaction. However, the emergence of glycine-Amadori under a basic initial pH could not facilitate the production of sulfur-containing compounds, since glycine- Amadoris could react with cysteine to form stable thiazolidine derivatives, which can cause the Maillard reaction to develop sulfur flavor compounds.

Naturally fermented soybean pastes were prepared by the same method as that for traditional fermented soybean paste in northeast China with different fermentation periods, and they were investigated for changes in protein content and amino acid composition during the fermentation. In addition to the contents of protein, amino nitrogen, amino acids and non-protein nitrogen and hydrolysis index, amino acid score (AAS), chemical score (CS) and essential amino acid index (EAAI) were also analyzed. The results showed that the content of protein, non-protein nitrogen, and proteolysis index of soybean pastes were increased at first and then decreased, but amino nitrogen content was increased until reaching a plateau. A total of 17 kinds of amino acids were measured in the naturally fermented soybean pastes. It turned out that, with the fermentation, the contents of different amino acids were extremely different. The total amount of amino acids in the ripen soybean pastes remained at around 41.00 mg/g, which was significantly higher than that of raw soybean flour (11.42 mg/g) and cooked flour (11.06 mg/g). The ratio of essential amino acids to non-essential amino acids (E/N) was changed from 0.48 to 0.77, which proved that the soybean pastes contained high quality protein. Based on analysis of AAS, CS and EAAI, the EAAI reached the highest value of 29.41 on day 20 of fermentation and then was decreased to a stable level in the range from 16.16 to 17.40 during day 50 to 75. The contents of different taste-active amino acids were in the order of sweet amino acid > bitter amino acid > umami amino acid > tasteless amino acid.

Solid phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS) and relative odor activity value were used to study the key volatile compounds of fermented cow milk produced by pure and mixed cultures of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus. The results showed that 100 volatile compounds, including acids, ketones, aldehydes, alcohols, estersds, hydrocarbons and aromatic compounds were detected. Principal component analysis (PCA) indicated that 2,3-butanedione, nonanal and toluene were the characteristic aroma compounds of fermented cow milk produced by a pure culture of S. thermophiles while hexanal, butanoic acid-2- methylpropyl ester and 1-heptanol were the characteristic aroma compounds of fermented cow milk produced by a pure culture of L. bulgaricus. Acetaldehyde, 3-methyl-butanal, acetoin, 2-nonanone, 2-heptanone, acetic acid ethenyl ester, carbonic acid-heptyl phenyl ester, formic acid-ethenyl ester, and 2-nonanol were the characteristic aroma compounds of fermented cow milk produced by mixed cultures. Compare to fermented cow milk produced by pure cultures, the compositions of volatile compounds and their relative contents and the key volatile compounds were all changed in fermented cow milk produced by mixed cultures.

A comparison was performed of the flavor characteristics of three raw sauces fermented from rice dregs by pure and mixed starter cultures and raw soy sauce fermented by a pure starter culture in order to clarify the effects of cofermentation of Aspergillus oryzae with Zygosaccharomyces rouxii or Lactobacillus plantarum on sauce flavor. The results showed that the free amino acid content, taste active value (TAV), and the number and amount of volatile flavor components in raw soy sauce and raw rice dreg sauce fermented with mixed starter cultures were significantly higher than those of rice dreg sauce fermented with pure Aspergillus oryzae culture. Especially, the relative content of 4-vinylguaiacol in rice dreg sauce co-fermented with Aspergillus oryzae and Z. rouxii reached 9.71%. The results of electronic tongue showed that the principal components of four kinds of raw sauce differed obviously. The flavor of rice dreg sauce co-fermented with Z. rouxii was similar to that of soy sauce, both of which had good umami and weak sourness. Rice dreg sauce co-fermented with L. plantarum had a well-balanced taste and the best overall sensory quality. There were differences in overall flavor between rice dreg sauce and soybean sauce, but the optimized mixed culture fermentation significantly enhanced the flavor of rice dreg sauce.

Mulberry leaves, rich in nutrients and functional ingredients, is used as both food and medicine in China. In order to meet the demand for specialized edible mulberry varieties in the diversified development of mulberry trees, factor analysis method was applied to comprehensively evaluate the nutritional quality of leaves from 45 mulberry germplasms and varieties for the purpose of screening specialized mulberry varieties for edible leaves in this study. Results showed that 13 nutrients in leaves from 45 mulberry germplasms and varieties were obviously different and some nutrients had a significant correlation with each other, providing a theoretical basis for screening specialized mulberry varieties for edible leaves. In addition, the main factors influencing the nutritional quality of mulberry leaves were found to be harmful trace element factors, beneficial trace element factors, weight factors, carbohydrate factors and nutritional quality cofactors. The cumulative variance contribution rate of the seven factors above was up to 89%. Our results showed that Jialing No.20, Hongguo No.1 and Baiyuwang were ranked as the top three respectively based on comprehensive evaluation of the nutritional quality of mulberry leaves. Among these Jialing No.20 was the optimal candidate variety for a high yield of edible mulberry leaves.

The volatile components of 16 typical samples of Qingzhuan dark tea were analyzed using sensory evaluation and headspace solid-phase micro-extraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). The result showed that pure stale flavor as well as arohid or woody flavor was good for the aroma characteristics of Qingzhuan dark tea. A total of 72 aroma compounds were identified, and among them, hexanal, linalool, nonanal and toluene were the major components. Aldehydes and ketones were the principal aroma types. The aroma score obtained by sensory evaluation was correlated highly significantly with the levels of (E,E)-2,4-heptadienal, (Z)-linalool oxide, camphor, 1-methylnaphthalene and longicyclene (P < 0.01), and significantly with (E)-2-hexenal, 1-methoxy-4-methyl-benzene, (E)-2-nonenal, 2,2,6-trimethylcyclohexanone and the proportion of olefine aldehyde as an aliphatic aldehydes in total aldehydes (P < 0.05). Principal component analysis showed that the sixth principal components contributed 82.250% to the aroma quality of Qingzhuan dark tea, and the main representative components were β-cyclocitral, β-ionone, dihydro-β-ionone, hexanal, (E)-2-pentenal, (E)-2-hexenal, heptanal, nonanal, decanal, naphthalene, 1-methylnaphthalene, limonene and 6-methyl-5- heptene-2-one, suggesting that they are the key aroma constituents influencing the aroma quality of Qingzhuan dark tea, which can basically reflect the flavor characteristics of Qingzhuan dark tea.

Polysaccharides from bone, muscle, and skin of turbot (Scophthalmus maximus) were extracted by sequential hydrolysis with trypsin and papain followed by alkali extraction or the reverse sequence for functional food application. The disaccharide fragments from turbot polysaccharides were analyzed using high performance liquid chromatographytandem mass spectrometry (HPLC-MS/MS) after trifluoroacetic acid (TFA) hydrolysis and 1-phenyl-3-methyl-5-pyrazolone (PMP) derivatization. The crude polysaccharides from fish bone produced by enzymatic pretreatment and alkali extraction contained the highest amounts of neutral polysaccharides (6.79 mg/g dried weight) and sulfated polysaccharides (3.81 mg/g dried weight). The uronic acid polysaccharides (UACPs) from fish bone were identified mainly as chondroitin sulfate (CS) by comparing their retention time and mass spectral data with those of standards, the UACPs from fish mainly included hyaluronic acid and chondroitin sulfate, and the UACPs from fish muscle mainly consisted of hyaluronic acid, heparin, chondroitin sulfate, a polysaccharide comprised of GlcA(1→2)-Man repeated units (AGSP), and an unknown polysaccharide UACP1 with repeats of uronic acid linked to hexose.

This study aimed to develop a high performance liquid chromatography (HPLC) method for the simultaneous determination of the contents of five nucleoside (uridine, inosine, guanosine, adenosine and cordycepin) in cultured Cordyceps militaris. An ultrasonic-assisted ionic liquid microextraction procedure was proposed using [C4MIM]PF6-20% methanol as extraction solvent for sample pretreatment. The method was performed on an Inert Sustain C18 column (4.6 mm × 150 mm, 5 μm) with methanol-0.02 mol/L KH2PO4 solution as mobile phase at a flow rate of 0.6 mL/min by gradient elution. The column temperature was 30 ℃ and the detection wavelength was set at 254 nm. The highest extraction yields of five nucleosides were obtained by using 0.7 mol/L [C4MIM]PF6-20% methanol solution as extraction solvent at a solid-to-liquid ratio of 1:50 (g/L), pulverizing samples to pass through a 50-mesh sieve, ultrasonic irradiation for 50 min, and centrifugation at 3 000 r/min. A good linearity was observed in the range of 0.568?3.408, 0.284?1.704, 0.264?1.584, 0.232?1.392 and 1.672?10.032 mg/mL for uridine, inosine, guanosine, adenosine and cordycepin, respectively, with correlation coefficients above 0.999 8. The average recoveries were in the range of 97.6%?101.5%, with relative standard deviation (RSDs) ranging between 1.43% and 1.97%. The method was rapid, simple and sensitive, and it could be applied for rapid analysis of five nucleosides in cultured C. militaris.

The effect of adding different amounts of Chinese prickly ash, a commonly used spice, on the microflora and flavor of Harbin air-dried sausage was explored. Towards this goal, the selective medium was used to isolate microbial populations from air-dried sausage. Simultaneous distillation extraction (SDE) and gas chromatography-mass spectrometry (GC-MS) were used to determine the volatile flavor components. The results showed that Chinese prickly ash could adjust the relationship among the growth of Lactobacillus, Staphylococcus, Micrococcus, and yeast. Chinese prickly ash resulted in changes in volatile esters such as ethyl hydride, ethyl palmitate, ethyl linoleate and ethyl decanoate by affecting the microflora of Harbin air-dried sausage. Addition of Chinese prickly ash effectively inhibited the increase in the total number of colonies, significantly promoted the growth of lactic acid bacteria, and first promoted and then suppressed the growth of Staphylococcus aureus, Micrococcus and yeast during the fermentation. Co-addition of Chinese prickly ash and another spice(s) was more effect in promoting the growth of the dominant microorganisms and inhibiting the growth of harmful microorganisms than Chinese prickly ash alone during the fermentation process, and was significantly better for flavor formation in Harbin air-dried sausage than single Chinese prickly ash and blank control. Conclusively, Chinese prickly ash had a significant impact on the microflora of Harbin air-dried sausage and thus changed the flavor of the product.

Hyperspectral imaging technology was used to detect the contents of polysaccharides and total sugar as two important quality indicators for rapid evaluation of Chinese wolfberry. For this purpose, the optimal spectral waveband was explored. Firstly, the original spectra were preprocessed using three commonly used methods, namely multiplicative scatter correction, Savitzky-Golay smoothing and standard normal variate, and comparison of the results obtained showed that multiplicative scatter correction was selected to eliminate the scattering effect. Then the average spectral reflectance value was extracted for use as characteristic parameters from hyperspectral images in the effective wavebands, the visible wavebands, the near-infrared wavebands and the full wavebands based on the correlation coefficients and the spectral characteristics in different waveband ranges. Finally, BP neural network models were established based on different characteristic parameters to predict the contents of polysaccharides and total sugar in Chinese wolfberry. The results showed that the prediction model based on the full bands was the best one. The correct prediction rate of the model for polysaccharide content was 97.59% with a correlation coefficient of 0.997 4 and a root mean square error of 0.077 7. The correct prediction rate of the model for total sugar content was 100% with a correlation coefficient of 0.996 8 and a root mean square error of 0.250 6. Therefore, it is feasible to detect the contents of polysaccharide and total sugar in Chinese wolfberry by hyperspectral imaging technology.

The thin layer hot-air drying characteristics of rough rice as a function of hot-air temperature, initial moisture content and air velocity were investigated by using an orthogonal array design and the applicability of 10 mathematical models for the hot-air drying process of rough rice was compared. The results showed that no apparent constant-rate drying period existed in the hot-air drying process, and moisture removal mainly occurred in the falling-rate drying period; hot-air temperature was the main factor that affects the hot-air drying, followed by air velocity. The optimal hot-air drying conditions for rough rice were determined as follows: initial moisture content, 20%; hot-air temperature, 50 ℃ and air velocity, 1.4 m/s. The Page Model was found to be the best mathematical model for describing the drying characteristics of rough rice under these conditions; tempering could effectively inhibit the occurrence of fissuring, and a better effect was observed by raising tempering temperature and prolonging tempering time. Under the conditions of initial moisture content of 24% and air velocity of 1.4 m/s, the relative mean deviation between the experimental and predicted results were 1.563% and 1.474%, respectively. The predictive drying curves fitted well the experimental data. With temperature increase from 40 ℃ to 60 ℃, the effective moisture diffusion coefficient of rough rice increased from 9.69 × 10-10 to 10.77 × 10-10 m2/s, and the activation energy for rough rice drying was 47.1 kJ/mol.

This research was conceived to optimize the ultrasonic-assisted enzymatic extraction of flavonoids from mung bean coat by using a Box-Behnken design with response surface methodology (RSM). A quadratic regression model was established using Design-Expert software version 8.0.5.0 based on a Box-Behnken statistical design to describe the yield of flavonoids as a function of ultrasonic power, ultrasonication time, enzyme dosage and hydrolysis time. The optimal extraction conditions were determined as follows: ultrasonic power, 192 W; ultrasonication time, 28 min; enzyme dosage, 0.24%; and hydrolysis time, 40 min. Under these conditions, the yield of flavonoids was experimentally measured to be (0.831 ± 0.02)% (n = 3). Good agreement was observed between the experimental and model predicted values, indicating good fitness. Compared with conventional ultrasonic extraction, the yield of flavonoids was improved by 18.54% using the combined procedure. Spectroscopic analysis showed the characteristic peaks of flavonoids, confirming the presence of these compounds in mung bean coat extracts. By ultra high performance liquid chromatography (HPLC) analysis, the coat of germinating mung beans mainly contained vitexin (51.99%) and isovitexin (45.42%).

The significance of developing amino acid-chelated copper is evident to reduce environmental pollution and nutrient wastes caused by the use copper inorganic salts in food and feed processing. In this experiment, L-hydroxyproline (L-Hyp) was prepared and separated from food grade pig skin gelatin and further used to obtain L-hydroxyproline-Cu(Ⅱ) (L-Hyp-Cu(Ⅱ) with CuSO4·5H2O by sequential microwave irradiation and solid-state synthesis under pressurized conditions. The synthesis conditions were established as follows: after thorough mixing of L-Hyp with CuSO4·5H2O at a molar ratio of 2.5:1 namely 10.5:8.0 (m/m), the reaction was triggered by adding 20 mL of water followed by addition of 5.6 g of anhydrous Na2CO3 for acid removal under microwave irradiation for 180 s at 600 W, and then transferred to a pressurized reaction kettle at 90 ℃ and 15 MPa with an agitation speed of 100 r/min for 35 min. The composition and structure of the final product were characterized by ultraviolet (UV) spectroscopy, infrared spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), coordination analysis, elemental analysis and gravimetry. Results indicated that this synthesis procedure gave higher chelate rate of L-Hyp-Cu(Ⅱ), reaching 86.4%. The chelating reaction between copper (Ⅱ) and carboxyl and imino groups in L-Hyp to fomr L-Hyp-Cu(Ⅱ) with a coordination ratio of 1:2, whose molecular formula was established as Cu(C5H8NO3)2.

Objective: To examine the effect of processing conditions on the formation of acrylamide in green tea. Methods: The quantitative analysis of acrylamide was conducted by liquid chromatography-triple quadrupole mass spectrometry (LCTQ- MS). The optimization of the processing conditions with respect to fixation methods, rolling time and drying methods was investigated for reduced formation of acrylamide using an L9 (34) orthogonal array design. Results: Hot air drying temperature was found to have the greatest influence on acrylamide formation, followed sequentially by rolling time and fixing temperature, and the optimal values of these variables were 150 ℃,30 min and 150 ℃, respectively. Conclusions: Microwave treatment was more conducive to the formation of acrylamide in green tea than conventional heat treatment. More acrylamide was formed with increasing fixing temperature, and less acrylamide was formed with increasing drying temperature and rolling time.

In this study, qualitative and semi-quantitative analysis of volatile and semi-volatile potential migrants in 12 infant food contact thermoplastic elastomer (TPE) products were carried out by solid phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS). Non-target compounds were extracted by divinylbenzene/carboxen/ polydimethylsiloxane (DVB/CAR/PDMS), CAR/PDMS and polyacrylate fibers, and separated and identified by GC-MS. A total of 68 compounds were detected and further confirmed by comparison of retention indices with those of reference standards, and the semi-quantitative analysis of these compounds was carried out by single point internal standard method. All the compounds were filtered in sequence by three-step screening based on their detection rates, retention indices and contents. Finally, a total of 32 compounds, including siloxanes, aromatics, alkanes, aldehydes, esters and phenols, were regarded as being of concern. This study may provide a scientific basis for future studies on the migration and exposure assessment of specific substances.

Three lactic acid bacterial (LAB) strains (namely Lactobacillus casei, Lactobacillus plantarum and Pediococcus pentosaceus) with antioxidant activities, screened from traditional dry-cured fish, were used as starter culture to ferment drycured hairtail. The changes in lipid oxidation of dry-cured fermented hairtail during processing were determined in terms of pH value, peroxide value, acid value, thiobarbituric acid reactive substances (TBARS) value and hexanal content. Moreover, the effect of LAB fermentation on the fatty acid composition of dry-cured hairtail was analyzed. All indices were analyzed by principal component analysis (PCA) eventually. The results indicated that LAB fermentation could inhibit the oxidation of unsaturated fatty acids. The peroxide value, TBARS value, hexanal content and staturated fatty acid content of fermented dry-cured hairtail were significantly lower than those of traditional dry-cured hairtail, but the acid value and unsaturated fatty acid content were significantly higher than those of traditional dry-cured hairtail. The first principal component reflected the degree of lipolysis, while the second principal component reflected the degree of lipid oxidation. And the principal component functions were Y1 = 0.131X1 + 0.208X2 + 0.360X3 + 0.244X4 + 0.083X5 ? 0.388X6 + 0.324X7 + 0.343X8 and Y2 = 0.330X1 + 0.406X2 + 0.182X3 + 0.440X4 + 0.294X5 ? 0.205X6 + 0.135X7 + 0.157X8, respectively. These results provide a good theoretical basis for controlling the safety of fermented dry-cured fish.

An indirect competitive enzyme-linked immunosorbent immunoassay (ic-ELISA) based on chicken IgY was developed and validated for the detection of enrofloxacin (ENR) residues in animal-derived food samples. The ENR immunogen and coating antigen were prepared by the active ester method and confirmed by UV spectroscopy for further detection and immunization into laying hens. IgY antibodies were extracted with PEG-6000 precipitation. The titer of anti- ENR IgY attained its peak (1:32 000) after the fifth booster immunization. Checkerboard titration showed that 1:64 000 dilution of anti-ENR IgY could give OD around 1.0 at 38 ng/mL ENR-OVA coating concentration. The IC50 of the ELISA for ENR was 18.207 ng/mL and the regression curve equation was y = 0.891 1?0.016 5x (R2 = 0.990). The study demonstrated that anti-ENR IgY antibody was feasible for the detection of ENR in animal-derived food samples.

Purpose: To develop a method for the determination of diafenthiuron residue in tea by liquid chromatographytandem mass spectrometry (LC-MS/MS). Methods: The diafenthiuron in tea was extracted by acetonitrile and purified by the quick, easy, cheap, effective, rugged and safe (QuEChERS) method. The separation of the analyte was performed on a C18 column by gradient elution using a mobile phase consisting of acetonitrile and water (containing 0.1% formic acid). The mass spectrometer was operated with electrospray ion source in positive mode (ESI+) by selective reaction monitoring (SRM), and the analyte was quantified by the external standard method. Results: Low recoveries of diafenthiuron obtained by the method described in GB/T 23205?2008 was in part ascribed to the decomposition of diafenthiuron in the pretreatment processes. A good linearity (r = 0.999 9) was observed over the range of 1.0 to 500 μg/L using the new method developed in this study. The limit of quantification (LOQ) was 0.01 mg/kg, and the recoveries at three spiked levels (0.010, 1.0 and 5.0 mg/kg) varied from 83.3% to 99.4%, with relative standard deviations (RSDs) of 1.87%–6.30%. Conclusion: This method is simple and convenient, and it can effectively avoid the influence of diafenthiuron decomposition in the pretreatment process, and thus can be applied for the qualitative and quantitative confirmation of diafenthiuron residue in tea.

An utra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was established using quick, easy, cheap, effective, rugged, and safe (QuEChERS) pre-treatment to investigate the production and distribution of five Alternaria mycotoxins including tentoxin (Ten), alternariol (AOH), alternariol monomethyl ether (AME), altenuene (ALT) and tenuazonic acid (TeA) in whole fruits, healthy pulp and healthy peel of citrus inoculated with Alternaria alternate. The results demonstrated that the contents of various Alternaria mycotoxins produced in whole fruits, healthy pulp and healthy peel changed differently with increasing lesion diameter. TeA, Ten, AME and AOH were detected in all tested parts of the fruit. Among these, the average concentration of TeA was the highest, ranging from 3.05 × 103 to 55.88 × 103 μg/kg and from 65.35 to 40.68 × 103 μg/kg in lesion and non-lesion areas, respectively. The concentrations of Ten, AME and AOH in the infected location were in the range of 69.16?373.94, 22.63?1 395.82 and 8.18?689.19 μg/kg, respectively, while in the health location, the values were in the range of 0?67.56, 0?195.96 and 0?301.91 μg/kg, respectively. ALT was detected in both healthy peel and infected whole fruits (up to 16.61 μg/kg) rather than healthy pulp. These results indicate that Alternaria mycotoxins produced in infected citrus can rapidly spread from the infected to the healthy parts, resulting in the accumulation of a large amount of mycotoxins in citrus. Therefore, we should pay more attention to this problem in fresh food processing and risk assessment to ensure consumer safety.

Migration of contaminants from packaging materials into food is a big issue in food safety and quality, as it may pose a threat for consumers. With that in mind, it is necessary to study migration characteristics and mathematic modeling to predict the amount of migration. In this study, the migration of four kinds of ultraviolet absorbers (UV-327, UV-P, UV-9 and UV-531) from kraft paper to solid food simulants was investigated at 50, 75 and 100 ℃. Effects of temperature and physicochemical properties of the ultraviolet absorbers on migration were examined. Temperature played a key role in the migration process. The migration rate and final migration amount increased with temperature. Smaller molecular weight, lower values of lgPo/w and boiling points of migrants had a positive impact on the migration. The mathematic model based on Fick’s second law was built and applied to predict the migration amount of UV-P from paper into solid simulants at 70 ℃. The results showed that the built mathematic model could predict the migration amount very well in the initial period before equilibrium.

A novel method was developed for the qualitative and quantitative determination of estradiol based on its specific recognition by the DNA aptamer of optimum length as well as the changes in the color and absorbance of colloidal gold before and after aggregation. In this work, colloidal gold particles were prepared and the 75-mer, 35-mer and 22-mer estradiol-specific nucleic acid aptamers were designed for the ultrasensitive colorimetric detection of estradiol. The colorimetric method was based on the fact that the optimal concentration of sodium chloride leads to the aggregation of colloidal gold without the protection of the aptamer, while the colloidal gold does not aggregate under the protection of the aptamer. The results showed that the concentration of estradiol in the range of 13.6?54.4 pg/mL exhibited a good linear relationship with the absorbance ratio (A625 nm/A523 nm) of colloidal gold at 625 nm and 523 nm with a limit of detection (LOD) of 2.7 pg/mL, under the condition of 30 mmol/L sodium chloride and 30 nmol/L 35-mer nucleic acid aptamer. The developed colorimetric sensor had the advantages of high specificity, stability and reproducibility. The practicality of this proposed method was further confirmed through the detection of estradiol in milk samples with LOD of 13.6 pg/mL. Therefore, this colorimetric method will be useful for the rapid and sensitive detection of estradiol in milk products.

In this paper, a rapid method using conventional PCR after ethidium bromide monoazide (EMA) pretreatment is described for the detection of Lactobacillus brevis as a beer spoilage bacterium. The PCR amplification was carried out using the hop resistance gene horC as target gene and the genomic DNA from L. brevis as template. The results suggested that addition of EMA to a final concentration lower than 20 μg/mL for pretreatment did not strongly inhibit the PCR amplification of DNA derived from viable L. brevis cells, but it, when added to a final concentration of 1.0 μg/mL, completely inhibited the PCR amplification of DNA derived from 105 CFU/mL dead L. brevis cells. The detection limit (LOD) of EMA-PCR assay was found to be 104 CFU/mL beer sample for the horC gene. Moreover, the horC-specific EMA-PCR assay was applied to detect 13 strains of lactic acid bacteria, representing 100% specificity with no false positive amplification observed for five beer spoilage lactic acid bacteria and enabling discrimination between the live and dead cells. Overall, the use of horCspecific EMA-PCR allows for a substantial reduction in the rate of false-positive results for potential beer spoilage L. brevis.

In order to provide a theoretical basis for the online, rapid and nondestructive detection of apple diseases, hyperspectral imaging was adopted to study the nondestructive detection of diseases (mainly anthracnose, bitter pox disease, black fruit rot and leaf spot disease) in fruits of the apple cultivar ‘Hanfu’, which is widely planted in north China. The acquired hyperspectral images were used for segmentation of regions of interest and extraction of spectral information. Then, 10 feature wavelengths (502, 573, 589, 655, 681, 727, 867, 904, 942 and 967 nm) were extracted in the full wavelength range of 500–970 nm by successive projection algorithm (SPA1). Furthermore, three wavelengths (681, 867 and 942 nm) were selected out of these feature wavelengths by using this algorithm again (SPA2). Finally, the spectral data in the full wavelength range and at the feature wavelengths obtained after each selection step were used as input vector to build a linear discriminant analysis (LDA) model, a support vector machine (SVM) model and a BP artificial neural network (BPANN) model for the detection of diseases in apple. Analysis of the test results revealed that SPA2-BPANN was finally chosen as the best detection method, providing a correct detection rate of 100% for both training validation sets. Our results show that hyperspectral imaging allows effective detection of diseases in apples, and the characteristic wavelength obtained can provide a reference for the development of multispectral imaging for apple quality detection and classification system.

A novel molecularly imprinted electrochemical sensor was prepared by electro-polymerization on the glassy carbon electrode using tetramethrin as the template molecule and o-anminophenol as the functional monomer. A potential induction method for template molecule elution was studied. K3[Fe(CN)6] was regarded as an electroactive probe and the preparation of the sensor and the detection conditions were optimized using cyclic voltammetry and differential pulse voltammetry (DPV). Furthermore, the imprinting effect and analytical performance of the sensor were examined. The results showed that the potential induction method exhibited a good linear relationship between the concentrations of tetramethrin in the range of 0.2 to 10 μmol/L and DPV peak current difference and it provided better template elution than the traditional soak elution method. The detection limit of our method was 0.07 μmol/L, and the average recoveries of spiked samples were between 82.9% and 98.2%. The sensor had the advantages of simple operation, quick response, high sensitivity, good stability, high selectivity, strong anti-interference capability, and low cost, and thus it would have a good application prospect.

A new method that combined universal primer-multiplex asymmetric PCR and oligonucleotide microarray technology was developed for the simultaneous detection of seven common foodborne pathogens including Listeria monocytogenes, Salmonella, E. coli O157:H7, Staphylococcus aureus, Yersinia enterocolitica, Vibrio parahaemolyticu and a standard strain of Escherichia coli. The 5’-end of forward or reverse primer specific to each pathogen was linked with a non-homologous common sequence. Target fragments of all seven pathogens were enriched and labeled simultaneously by one-step multiplex asymmetric PCR using the Cy3-labeled common sequence as the universal primer. The labeled single-stranded amplicons were captured by the specific oligonucleotide probes immobilized on microarrays, followed by microarray scanning and analysis of fluorescence signal intensity. The results for reference strains indicated that the assay could unambiguously discriminate all seven pathogens in single and multiple infections, and it had a detection sensitivity of 0.1–1 pg of genomic DNA. Ninety-five artificially contaminated samples and retail food samples were tested by this assay, and the results agreed with those obtained with traditional culture methods and real-time PCR. This developed oligonucleotide microarray assay can provide a useful method for rapid, specific, sensitive and high-throughput detection of foodborne pathogens.

A rapid method for the simultaneous determination of 14 adulterated industrial dyes in chilli products was developed by using liquid chromatography-tandem mass spectrometry (LC-MS/MS) based on a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample pretreatment method. Samples were extracted with acetonitrile-acetone (7:3, V/V), and then the extract was cleaned up using Enhanced Matrix Removal Lipid (EMR-Lipid). The chromatographic separation was performed on an Agilent Poroshell 120 EC C18 (50 mm × 2.1 mm, 2.7 μm) column. The separated analytes were analyzed with LC-MS/MS by multiple reaction monitoring (MRM), and quantified by the external standard method. The results showed that the 14 pigments were separated completely in 11 minutes, and their quantitative detection limits ranged from 0.4 to 7.1 μg/kg. The average recoveries at three spiked levels ranged from 70.5% to 102.1% with relative standard deviations (RSDs)(n = 6) of 0.3%–9.3%. The method is quick, accurate, and sensitive, and can be applied to the determination of 14 adulterated industrial dyes in chilli products.

Two sets of specific primers were designed based on the conserved mitochondrial gene sequences of Alopex lagopus and Nyctereutes procyonoides and used to establish a PCR method to detect ingredients derived from A. lagopus and N. procyonoides in commercial meat products. Regular and clear A. lagopus- and N. procyonoides-specific bands were amplified simultaneously by duplex PCR. The sensitivities of the A. lagopus and N. procyonoides primers were respectively 10 pg and 1 pg in separate polymerase chain reactions, respectively. By contrast, the sensitivities of the A. lagopus and N. procyonoides primers were respectively 100 pg and 10 pg in duplex PCR due to the competition of two sets of primers.

Goat milk adulterated with proteins was qualitatively discriminated and quantitatively analyzed using electronic nose combined with chemometric methods. Milk samples adulterated with different proteins were detected by electronic nose and then the response values were analyzed qualitatively by principal component analysis (PCA), and linear discriminant analysis (LDA) and quantitatively by linear regression analysis, Fisher discriminant analysis (FDA) and K nearest neighbor (KNN) analysis. The results showed that PCA and LDA were able to distinguish different adulterants. The determination coefficient of linear regression analysis was 84.5%, indicating high reliability of the regression equation. The accuracy of the original classification by FDA reached 100.0%, and the accuracy of cross validation was 98.2%, indicating good predication performance. The classification accuracy of the training set by KNN analysis was 95.1%, and the classification accuracy of the validation set was 97.1%, indicating good prediction performance of the model. All of these results showed that it is feasible to apply electronic nose technology in recognition of protein adulteration in goat milk.

Different commercial brands of sesame paste and sesame paste produced from different cultivars as well as sesame paste adulterated with various amounts of peanut paste were tested by electronic nose. The response signals were analyzed by principal component analysis (PCA), discriminant fact analysis (DFA), partial least-squares analysis regression (PLSR) and statistical quality control (SQC). The results showed that different brands of black sesame paste and white sesame paste and mixed sesame pastes could be effectively identified by electronic nose. The response to the addition of adulterant (0%, 5%, 10%, 20%, 40%, 60%, 80% and 100%) was linear with a high correlation coefficient (R2) of 0.99. The established partial least squares regression (PLSR) model gave a prediction error ranging from 0.7% to 2.7%. It was proved that electronic nose could be applied in sesame paste discrimination.