In this study, amino acid motifs and evolutionary relationship of 59 tomato nuclear transcription factor Y (NF-Y) members were analyzed using bioinformatics approaches. Furthermore, changes in the expression pattern of tomato NF-Y genes in the wild-type AC and ripening inhibitor (rin) mutant were investigated during fruit ripening. On the basis of the NF-Y gene binding capacity of the transcription factor RIN, their co-regulation on tomato fruit ripening was elucidated.

In order to improve its L-asparaginase activity, the L-asparaginase gene of Bacillus licheniformis was molecularly modified by directed evolution. Mutants S10, S16 and S21 were screened out of more than 19100 mutants by two rounds of error-prone PCR and one round of DNA shuffling, whose specific activities were increased by 106%, 74% and 43%, respectively, as compared to that of the wild type, together increased Kcat/Km. The amino acid sequence of S10 showed three mutations, K43E, N67S and I269L. The results of three-dimensional simulation showed that amino acid mutations at position 43 for glutamic acid and at position 67 for serine may improve substrate affinity and catalytic efficiency, thereby increasing enzymatic activity. The circular dichroism analysis showed that the mutant enzymes contained less α-helix and more random coil than the wild enzyme, indicating a slight decrease in rigidity and an increase in flexibility. This study indicates that directional evolution can effectively improve the L-asparaginase activity from B. licheniformis.

The aim of this study was to evaluate the potential of Bifidobacterium RH to be used as a probiotic product. We examined the viability of the probiotic under simulated gastrointestinal conditions and we investigated the production of probiotic microcapsules with resistance to various negative factors. The bacterial counts were 107 CFU/mL and 106 CFU/mL, respectively, under simulated gastrointestinal conditions separately and sequentially. The optimized wall material of microcasuples contained l0% glycerol, 0.50% sodium alginate, 1.50% whey protein, 1.25% Arabic gum and 1.25% soybean lecithin as determined by one-factor-at-a-time and orthogonal array designs. The count of viable Bifidobacterial cells in the microcapsules was 1.80 × 1012 CFU/g, and with respect to encapsulation efficiency, the results showed a mean value of 96.04%. Thus, the study demonstrated that microencapsulated Bifidobacterium RH could be resistant to simulated gastrointestinal conditions. The microencapsulation process was shown to efficiently increase the viability of probiotic cultures, and the microorganism was released from the microcapsules. This study may provide a theoretical and technical support for the development of probiotic products containing Bifidobacterium RH.

In order to improve glutathione production by Candida utilis SZU 07-01, the effects of addition of L-methionine and L-cysteine on glutathione biosynthesis during batch and fed-batch fermentation, respectively, were investigated. The results indicated that addition of L-methionine improved the glutathione biosynthesis ability of yeast during cell growth phase while addition of L-cysteine significantly enhanced the production of glutathione after cell growth. Based on this finding, a two-stage strategy for amino acid addition was proposed for high glutathione production, that is, 60 mmol/L of L-methionine was added into the medium at the beginning of fermentation (0 h), and 30 mmol/L of L-cysteine was then added when the biomass achieved the maximum level (27 h) during fed-batch culture. The two-stage strategy ultimately resulted in further improvements in glutathione production and intracellular glutathione content, which were 1 247.1 mg/L and 24.1 mg/g at 48 h, respectively. The successful application of the two-stage amino acid addition strategy for improved glutathione production also provides a feasible approach for the efficient production of other similar compounds.

In order to clarify the dominant mould species causing postharvest decay of sweet cherry in Yantai, spoilage moulds from decayed sweet cherry fruits were screened and identified by internal transcribed spacer (ITS) sequence analysis. Typical strains were examined for colonial morphology and then re-inoculated into sweet cherry to test their pathogenicity. A total of 60 moulds were isolated from decayed sweet cherry from different regions of Yantai, and they were assigned to 6 species based on both ITS sequence analysis and morphological identification, Mucor racemosu, Fusarium tricinctum, Alternaria alternate, Penicillium polonicum and Aspergillus fumigatus. The predominant species were Alternaria alternate (14 strains) and Mucor racemosu (15 strains). Compared with naturally decayed sweet cherry, sweet cherries inoculated with moulds were decayed and displayed the same colonial morphology.

This study aimed to investigate the enzyme that might be involved in this process. Cathepsin L was purified to homogeneity from the hepatopancreas of Litopenaeus vannamei, and its molecular mass was approximately 31 kD as analyzed by sodium dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE). Peptide mass fingerprinting revealed that 8 peptide fragments with a total of 112 amino acid residues were completely identical to the cathepsin L gene of L. vannamei. Using Z-Phe-Arg-MCA as substrate, the proteinase revealed optimal activity at 35 ℃ and pH 5.5, respectively. Purified cathepsin L was stable at temperature up to 40 ℃ and in the pH range from 5.5 to 6.5. It exhibited high specificity towards the substrate Z-Phe-Arg-MCA. Its enzymatic activity was significantly suppressed by the cysteine proteinase inhibitors E-64 and leupeptin, while it could be slightly activated by the metalloproteinase inhibitors ethylene diamine tetraacetic acid (EDTA) and ethylene glycol tetraacetic acid (EGTA). In addition, the fibrous structure of shrimp meat was increasingly destroyed with the prolongation of cold storage time as observed by scanning electron microscope (SEM). Purified cathepsin L effectively hydrolyzed muscular proteins as detected by SDS-PAGE, suggesting its potential involvement in the degradation of shrimp muscular proteins during cold storage.

The present study compared the heat, acid and bile resistance of biofilm and planktonic cells of L-ZS9 by colony counting method. The results showed that biofilm cells had stronger stress resistance than their planktonic counterpart. The transcriptional levels of the stress resistance-related genes atpβ, atpε, clp, pspC and ccpA and the luxS gene encoding the quorum sensing signal autoinducer 2 (AI-2) synthase were investigated in biofilm and planktonic cells through real-time PCR. The results showed that the transcriptional levels of these genes were up-regulated in biofilm cells compared to planktonic cells. AI-2 activity were measured by its ability to induce luminescence in the reporter strain Vibrio harveyi BB170 and the results showed that the supernatant of biofilm cells had higher AI-2 activity than planktonic cells. Exogenous AI-2 could regulate the transcriptional levels of the atpβ, atpε, clp, ccpA and luxS genes. This study suggested that biofilm protected the cells by physical defense and biofilm cells differed from planktonic cells in terms of the transcriptional levels of the investigated genes. The quorum sensing system played an important role in the formation and regulation of biofilm. This work has laid a foundation for producing functional foods based on biofilm probiotics with high activity.

In this study, the actA and inlB double gene deletion mutant (EGDe ΔactAΔinlB) of Listeria monocytogenes wild-type (WT) strain EGDe was used as the parent to delete the dal gene by homologous recombination technology, and the biological characteristics of the dal-deficient mutant such as growth capacity, virulence gene expression, cell invasion and biofilm formation were further studied. Growth curves showed that the concentration of the new mutant strain was significantly lower than that of EGDe ΔactAΔinlB after 6 h of shaking culture at 37 ℃ (P < 0.001), but there was no difference in the growth rates of the parental and the mutant strains when D-alanine was added to the medium. Quantitative real-time-PCR showed that the sigB gene expression level of the mutant strain was changed most significantly (P < 0.01) and down-regulated by 90% compared with EGDe ΔactAΔinlB. The biofilm formation of the mutant strain increased compared with EGDe ΔactAΔinlB, but this difference did not exist when D-alanine was added to the medium for the mutant. There was no significant difference in Caco-2 cells invasion ability compared with EGDe ΔactAΔinlB. The results indicated that the dal gene played an important regulatory role in the growth and biofilm formation of bacteria and did not affect the ability of cell invasion. The construction of this deletion strain can provide a tool for further study of the function of the dal gene.

The effects of different factors on the synthesis of theaflavins from tea polyphenols by crude polyphenol oxidase (PPO) from the leaves of Camellia sinensis var. assamica cv. Mengku were analyzed. The results showed that pH 4.0, temperature of 37 ℃, a substrate concentration of 4.5 mg/mL and a reaction time of 1 h were found to be optimum for the synthesis of theaflavins. Under these conditions, the product yield reached (461.12 ± 15.01) μg/mL and the conversion of substrate was (15.31 ± 0.40)%. Additionally, ester theaflavins were the major products of the crude PPO and EGC and GA were also generated during PPO oxidation, which benefited the synthesis and accumulation of theaflavins. These results may be related to the high quality of Dianhong black tea.

Objective: The aim of this study was to explore the growth and esterase activities in the mixed culture fermentation of non-Saccharomyces yeast and Saccharomyces cerevisiae. Methods: Esterase activities of non-Saccharomyces yeast from southern Sichuan liquor pits were measured in liquid fermentation medium. One yeast strain with the highest esterase activity was selected and identified through sequence analysis of the D1/D2 domain of 26S rDNA. Then, the alcoholic fermentation of mixed cultures of the isolate and S. cerevisiae were performed in model grape juice medium to explore the yeast growth kinetics and the evolution of esterase activities from substrates with different carbon chain lengths (C2–C8). Three experimental groups were set up by inoculating the non-Saccharomyces yeast strain 48 and 96 h before or at the same time as S. cerevisiae, and their pure cultures were used as controls. Results: The isolate was identified as Pichia fermentans. The fermentation rate of pure S. cerevisiae was the fastest. The yeast population in mixed culture fermentation was higher, especially with 96 h sequential inoculation. During fermentation, the highest esterase activities were accumulated with simultaneous inoculation (574 mU/mL). The C8 substrate accumulated the highest esterase activity (178–227 mU/mL), while the C2 accumulated esterase activity was the lowest (46–66 mU/mL). Comparison of the cell growth kinetics and the evolution of esterase activities during fermentations revealed that esterase activities were correlated with the growth of yeasts and arrived at the highest value in the stationary growth phase. Conclusion: The simultaneous inoculation of the isolate and S. cerevisiae in model juice with higher C4-C8 accumulated esterase activities has a good application potential for aroma enhancement.

An immobilized enzyme roller was developed by immobilizing cellulase and neutral protease?onto polypropylene microporous membrane modified by?cellulose acetate,?respectively. Soybean flakes were rolled sequentially with the cellulose roller followed by the neutral protease roller and then used for the production of cold-pressed oil. Hydrolysis conditions were optimized by one-factor-at-a-time method and response surface methodology. An air relative humidity of 86.0%, an operating temperature of 55.0 ℃ and a rolling time of 91.0 min were found to be the optimal conditions to obtain a higher oil yield of 73.8% and a lower degree of protein denaturation. After seventh repeated use, both immobilized enzyme rollers retained more than 80% of their initial activities.

Five fungal strains isolated from naturally infected cherry fruit were purified, re-inoculated and identified as pathogens of cherry fruits. The results of morphological characterization and ribosomal DNA internal transcribed spacer (rDNA-ITS) analysis showed that strain 319#, 323#, 367#, 369# and 370# were identified as Rhizopus stolonifer, Diaporthe perniciosa, Epicoccum nigrum, Monilinia laxa and Penicillium cyclopium, respectively. In this study, D. perniciosa, E. nigrum and P. cyclopium were isolated from cherry fruits for the first time.

The fermentation of Fuji apple juice by lactic acid bacteria was optimized and changes in organic acids during fermentation were analyzed. Lactobacillus paracasei 20241, Bifidobacterium animalis 6165, Streptococcus thermophilus 6063 and Lactobacillus acidophilus 6005 were used as mixed cultures in the fermentation of apple juice. The optimization of culture composition, inoculum size and fermentation time was performed using one-factor-at-a-time method and response surface methodology. Viable cell count and sensory score were used as response variables. The results showed that the optimal fermentation conditions were as follows: ratio of four probiotic strains, 1:1:1:1; inoculum size, 2%; fermentation time, 24 h; and temperature, 37 ℃. Under these conditions, viable cell count was 1.985 × 108 CFU/mL and sensory score was 80.23 points. Malic acid and succinic acid contents decreased significantly after fermentation (P < 0.05), while lactic acid, quinic acid, citric acid, tartaric acid, pyruvic acid and shikimic acid contents significantly increased (P < 0.05) as demonstrated by HPLC analysis.

This study aimed to observe the changes in IgE binding ability of parvalbumin (major allergen) from sea bass Lateolabrax japonicus during fermentation by Staphylococcus xylosu (Sx). The alterations of proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The effects of fermentation by Sx on the allergenicity of allergens were investigated by Western blot and enzyme linked immunosorbent assay (ELISA) with rabbit anti-parvalbumin polyclonal antibody and sera from fish allergic patients. Subsequently, digestion of sarcoplasmic proteins by simulated gastric fluid (SGF) was carried out to evaluate the digestive stability. The results of SDS-PAGE showed that many proteins were degraded, although no obvious changes in parvalbumin (PV) were detected whose molecular mass was about 10 kD. The IgG binding ability of PV was decreased by 26.9% while the IgE binding ability was decreased by 22.3% after 60 h of fermentation. In SGF system, PV in fish fermented for 60 h was decomposed after being digested for 5 min, compared with 20 min of digestion for unfermented fish. In conclusion, the IgE binding ability of sea bass PV could be significantly reduced by fermentation with Sx, and PV was more readily degraded by pepsin after being fermented for 60 h.

In this study, the hydrolysis conditions for preparing egg yolk protein hydrolysate (EYPH) from defatted egg yolk were optimized based on the viability of MC3T3-E1 cells when cultured in the presence of EYPH. Additionally, we also evaluated the promoting effect of EYPH on proliferation and differentiation of MC3T3-E1 cells. The results showed that the hydrolysis with trypsin alone yielded a product with stronger cell proliferation promoting activity than when it was used in combination with flavourzyme. The optimum hydrolysis conditions for trypsin were as follows: hydrolysis time, 6 h; temperature, 37 ℃; enzyme-to-substrate ratio, 1:50; and pH, 8.0. EYPH prepared under the optimized conditions increased the viability of MC3T3-E1 cells by 9.1% and the proportion of S-phase cells by 4.69% indicating that EYPH significantly increased the proliferation of MC3T3-E1 cells. EYPH significantly affected differentiation and mineralization of MC3T3-E1 cells as indicated by a 9.1% increase in alkaline phosphatase activity, an increase in osteocalcin secretion of 2 mg/mL, and the formation of more mineralized nodules of MC3T3-E1. Furthermore, EYPH also could stimulate the expression level of RUNX2 gene by 6.12 times. These finding showed that EYPH could significantly promote proliferation and differentiation in osteoblastic MC3T3-E1 cells. Therefore, EYPH has the potential to be used as a functional food ingredient for its anti-osteoporosis activity.

Protease-producing bacteria were isolated from traditional shrimp sauce by using casein agar medium containing 10% NaCl. Based on its morphological, biochemical and molecular properties, Virgibacillus sp. P-4 was determined as target strain for further study. The strain grew best at 30–37 ℃ with a salinity of 5%–15%. The protease produced by Virgibacillus sp. P-4 showed the optimum activity at 40 ℃, and was stable in the range of 20–50 ℃. The enzymatic activity reached its peak when NaCl concentration was 15%. Besides, Virgibacillus sp. P-4 might produce more than one extracellular protease except sulfhydryl protease. According to the rate of release of free amino acids, the protease might preferably hydrolyze peptides containing Phe-, Tyr-, Lys-, His-, Pro- and Leu-.

To increase the yield of bacteriocin produced by Lactobacillus plantarum P158, the medium and culture conditions for this strain were optimized using one-factor-at-a-time and orthogonal array design methods. The bacteriostatic activity of bacteriocin against Micrococcus luteus and Pseudomonas aeruginosa and pH were used as response variables. Results showed that MRS was the most suitable for bacteriocin production among five culture media for lactic acid bacteria.The optimal culture conditions were obtained as follows: inoculum amount, 3% (V/V); initial pH, 6.0; and static culture at 34 ℃ for 42 h; the optimum medium was composed of glucose 2 g/100 mL, yeast extract 2 g/100 mL, soy peptone 1.5 g/100 mL, MgSO4 0.058 g/100 mL, MnSO4 0.025 g/100 mL, FeSO4 0.02 g/100 mL, Tween 80 0.08 g/100 mL, sodium acetate 0.5 g/100 mL, and K2HPO4 0.2 g/100 mL. Under these conditions, bacteriocin titer was 1 145 IU/mL, which was 216% higher than that (362 IU/mL) before optimization.

Developing indigenous yeast strains is currently one of the most important trends in the production of featured Muscat wine. In this work, 337 yeasts were isolated by using PDA medium from spontaneously fermented Muscat wine, and then they were identified, counted and classified into seven groups by using Wallerstein laboratory (WL) solid medium. According to the results of yeast counting, the dominant strains were determined and then they were inoculated to bismuth sulphite glucose glycine yeast (BIGGY) agar to select yeast strains without H2S production ability, and the selected strains were molecularly identified for further characterization of enological traits. The physicochemical indexes and volatile compounds of Muscat wine fermented with these yeasts in mono-cultures or co-cultures were studied. Based on our experimental results, the potential of using these autochthonous yeast strains in Muscat wine production were discussed. Out of 337 yeast strains, three were selected for less or no H2S production, which were cataloged as HBKS-Y1, HBKS-Y2 and HBKS-Y3, and molecularly identified as Saccharomyces cerevisiae, Hanseniaspora uvarum and Saccharomyces cerevisiae, respectively. The alcohol, SO2 and sugar tolerance of the 3 yeast strains were high and met the requirements of wine vinification. When they were used to must fermentation either in mono- or co-culture, the physicochemical indexes including reducing sugar, alcohol, total acids, volatile acids, glycerol and acetaldehyde contents were within the range for dry red wine. In mono-culture fermentation, HBKS-Y2 was a strong producer of total and volatile acids. When HBKS-Y2 was co-cultured with HBKS-Y1 and HBKS-Y3, a synergistic effect was observed, which resulted in a decrease in total acids content and a significant decrease in volatile acids content compared with single culture of HBKS-Y2 while having no disadvantageous effects on the physicochemical indexes of wine. Furthermore, significantly higher contents of terpene alcohols, the characteristic aroma compounds of Muscat wine, were produced by fermentation with indigenous yeasts especially in co-cultures compared with dry active yeast. These results suggest that HBKS-Y1, HBKS-Y2, and HBKS-Y3 can be used as a fermentation starter for Muscat wine, and their co-culture has potential use in improving the variety-specific aroma of Muscat wine.

Bacillus amyloliquefaciens SWJS22 and Aspergillus oryzae were used as starters for soy sauce fermentation in this paper. To study the effects of koji making on soy sauce fermentation, soy sauces produced with koji containing Aspergillus oryzae alone (control) and in combination with Bacillus amyloliquefaciens SWJS22 and with mixed koji cultures of the strains were tested for physicochemical parameters and flavor compounds. Compared with the control group and soy sauce fermented by koji containing mixed strains, soy sauce fermented by mixed koji cultures showed higher amino acid conversion, lower color index and lower pigment content. Soy sauce fermented by mixed cultures had a significantly higher content of glutamic acid compared with the control group. Comparative analysis of flavor compounds by gas chromatograph-mass spectrometry (GC-MS) indicated that only a slight difference was seen in the flavor substances of three soy sauces and the important ones were detected in all of them. The content of acids was lowest in soy sauce fermented by mixed koji cultures.

High throughput sequencing (HTS) was used to investigate the dynamics of eukaryotic microbial community succession during the fermentation process of special-flavor liquor. Microbial samples were collected by washing the surface of fermented grains from the bottom of fermentation cellar (0 and 30 d) and from the top and middle (0, 3, 6, 10, 15, 20, 25, and 30 d), and their genetic DNA was then extracted. The 18S rRNA regions of fungal rRNA genes were amplified by PCR. The dominant microbial populations and their succession dynamics were determined by pyrosequencing. The diversity and abundance index of fungal microbial communities showed a decreasing tendency during the fermentation process. Moreover, Saccharomycetales was the predominant order and Saccharomyces, Pichia and Galactomyces were the predominant genra on top and middle fermented grains during the whole fermentation process. The eukaryotic microbial communities identified from bottom fermented grains were more complicated, with the dominant species being Saccharomycetales, Eurotiales, Capnodiales and Tremellales. Furthermore, principal coordinate analysis (PCoA) results revealed that no obvious difference in fungal communities between the top and middle fermented grains was observed during the fermentation process of special-flavor liquor.

Saccharomyces boulardii was entrapped in alginate microcapsules by the emulsification/internalgelation method and was cultured in YPD liquid medium. The characteristics of growth and metabolism of microencapsulated yeast were studied and the mechanism for its increased stress resistance was elucidated with the free non-encapsulated one as control. The results showed that more living cells of S. boulardii were obtained and more ethanol was generated in the form of microcapsules compared with the control group. Extracellular glycerin concentration decreased, while intracellular glycerol concentration increased significantly in microencapsulated culture; the extracellular glycerin concentration of microencapsulated cells was 157.3% higher than that of free non-encapsulated cells. Furthermore, compared to free culture, the intracellular trehalose content of microencapsulated S. boulardii was significantly increased by 110.3%. In conclusion, the microcapsule could provide a microenvironment that enabled encapsuled S. boulardii to grow stably, and facilitated the accumulation of glycerol and trehalose inside the cells, resulting in an improvement of their stress resistance.

For a better understanding of the distribution and basic characteristics of the proteins with glutaminase activity from the microbial flora in the fermented mash of soy sauce, bioinformatics was used to conduct their classification, screening, signal peptides analysis, phylogenetic tree analysis, physicochemical properties prediction and homology modeling of 3-dimensional (3-D) structure. It was found that the proteins with glutaminase activity were divided into 3 categories, participating in glutamine catabolism, biosynthesis and transamination of glutamine, respectively. None of the proteins with glutaminase activity contained signal peptide sequence except 4 glutaminases. Two distinct evolutionary directions were found between bacterial and fungal glutaminase groups by phylogenetic tree analysis. Secretory glutaminases showed slight hydrophilicity with pIs of 4.81?5.99. The structural homology between glutaminases from Enterobacter lignolyticus, Citrobacter freundii and those from Escherichia coli and Bacillus subtilis was shown by 3-D homology modeling.

An oxidized chicken fat-glutathione-glucose model reaction system was designed and the reaction was allowed to proceed at 131 ℃ under pH 6.5 for 5 h. Volatile flavor compounds in the reaction products were extracted by solvent assisted flavor evaporation (SAFE) extraction, and analyzed by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) combined with aroma extract dilution analysis (AEDA). As a result, a total of 89 volatile compounds were identified, 67 of which were revealed to be aroma-active according to their mass spectra, linear retention indices and odor characteristics by co-injection with authentic standards. Among them, 10 alkyl-chain compounds were found, including 2-heptylthiophene, 2-pentylthiophene, and 2-pentylpyridine, which were formed by the interaction of lipid oxidation and degradation with the Maillard reaction. Besides, the compounds solely generated from the Maillard reaction such as 2-methyl-3-furanthiol and 2-furfurylthiol as well as most alkyl-chain compounds such as 2-heptylthiophene, 2-methylpyridine and 2-ethylpyridine had a high dilution factor (Log3FD ≥ 5). Therefore, the interaction of lipid oxidization and degradation with the Maillard reaction of glutathione made a considerable contribution to the development of meaty flavor in the reaction system. These research results can provide a useful guidance for the preparation of meaty flavorings through controlled fat oxidization combined with thermal reaction.

Objective: To establish an ultra high performance liquid chromatographic (UPLC) method for determining the lupenone contents in the peel and flesh of Musa nana Lour. and Musa acuminata cv. Mas (AA) harvested at different times and to optimize the extraction conditions of lupenone. Methods: Samples were extracted with methanol by refluxing and the extracts were concentrated under reduced pressure. The analysis was performed on Waters ACQUITY UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm), with acetonitrile:water (85:15, V/V) solution as the mobile phase. The flow rate was 0.3 mL/min, column temperature was 30 ℃ and the detection wavelength was set at 206 nm. Results: No lupenone was detected in the flesh of Musa nana Lour. and Musa acuminata cv. Mas (AA), but high lupenone contents were detected in the peel. A good linearity of the calibration was observed in the range of 16.70?59.96 mg/100 mL (r = 0.999 6). The average recovery of lupenone was 99.00% and the precision expressed as relative standard deviation (RSD) was 3.0%. Conclusion: This method had the advantages of high recovery, good reproducibility, high specificity, high accuracy and simplicity. It was useful for the determination of lupenone in the peel and flesh of Musa nana Lour. and Musa acuminata cv. Mas (AA).

This study aimed to evaluate the difference in the characteristic flavor intensity of different lamb meats from different carcass cuts. The composition and content of free fatty acids in 15 lamb samples were determined by gas chromatography-mass spectrometry (GC-MS). Principal component analysis (PCA) was used to establish an evaluation model for the characteristic flavor intensity of lamb meat. The results showed that the contribution rates of the first three principal components were 56.654%, 17.476% and 14.287%, respectively and the cumulative contribution rate was 88.417%, which could not only accurately reflect the information on the original data, but also represent the basic information on free fatty acids. The correlation coefficient between the model results and traditional sensory evaluation was 0.939, indicating good consistency. Therefore, the evaluation model established by PCA was feasible and provided a new method for the evaluation of the characteristic flavor intensity of lamb meat.

Liubao tea is one of China’s most well-known teas with a long history of consumption, which has a unique aroma quality. The composition and relative contents of aroma components in a representative batch of Liubao tea were analyzed by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOFMS). A total of 307 aroma components were identified from the tea samples, including 7 enols, 23 alkenes, 5 amines, 20 alkanes, 14 aldehydes, 14 olefin aldehydes, 22 ethers, 7 alcohols, 10 esters, 7 lactones, 5 allyl esters, 30 ketenes, 49 ketones, 5 phenols, 11 organic acids, 5 sulphur compounds, 20 nitrogen heterocyclic compounds, 7 oxygen heterocyclic compounds, 40 aromatic hydrocarbon compounds, 3 alkynes and 3 acid anhydrides, and 21 other compounds. The results showed that the aroma of Liubao tea was mainly composed of organic acids, aromatic hydrocarbon compounds, ethers, and aldehydes, and their relative contents were 16.55%, 13.50%, 10.92% and 10.04%, respectively. There were 54 aroma compounds accounting for less than 0.5% of the total amount of volatiles, the predominant ones being hexadecanoic acid (14.95%), benzaldehyde (3.03%), 3,7-dimethyl-1,6-octadien-3-ol, (2.19%) and (E,E)-2,4-heptadienal (2.04%). The analysis of characteristic aroma components showed that organic acids (such as hexadecanoic acid), aromatic hydrocarbon compounds (such as ethylbenzene), ethers (such as 1,2,3-trimethoxybenzene and 2-methoxy-naphthalene), aldehydes (such as benzaldehyde and 3-methyl-butanal) and ketones (such as α-ionone) may have a direct impact on the aroma quality of Liubao tea.

The proximate, nutritional and antioxidant constituents in hot pepper seeds of eight varieties, including Dingzhou Xinyidai, Chaotian, Yidu, Sipingtou, Hong’an No. 6, Jinta Honglong No. 13, Xinjiang Tianjiao, and Indian TEJA, were analyzed and compared. Dietary fiber, protein and oil were rich in hot pepper seeds, ranging from 40.10%–51.27%, 17.30%–19.83%, and 11.53%–16.70%, respectively. The seeds also contained 16 amino acids (15.16%–18.64%) and 9 minerals with potassium content of 7 790–11 566.67 mg/kg. Unsaturated fatty acids represented over 80% of the total fatty acids in the seeds of all the varieties tested, with the predominance of linoleic acid (7.04%–9.72% in the seeds), accounting for 72.20%–74.26% of the total fatty acids. The contents of tocopherol, ascorbic acid, total polyphenols, flavones and total capsicins in the seeds were 1.27–8.01, 0.24–2.36 mg/100 g, 11.43–20.22 mg GAE/g, 2.36–12.58 mg RE/g, and 0.07–5.21 mg/100 g, respectively. Xinjiang Tianjiao seeds contained the highest contents of dietary fiber and vitamin E of the eight varieties, Yidu seeds contained the highest contents of protein, oil and flavones and India TEJA seeds contained the highest contents of total polyphenols and capsaicins.

In order to more systematically and fully understand the quality characteristics of fragrant tea, the major chemical constituents, amino acid composition and aroma compounds in fragrant tea obtained from three producing areas, i.e. Songyang county, Suichang county and Wuyi county in Zhejiang province, were analyzed and compared in this study. Results showed that the levels of the major chemical constituents including total polyphenols, total free amino acids, caffeine, water extracts, total catechins and catechin monomers were slightly different (P > 0.05) among different producing areas, whereas the levels of amino acids including asparagine, proline and isoleucine were found to be significantly different (P < 0.05). A total of 49 aroma components were detected, with alcohols being the most predominant, including 14 compounds (together accounting for 35.33% to 46.19% of the total aroma compounds. Statistical analysis showed that significant differences in the levels of alcohols, aldehydes and ketones were observed among different areas (P < 0.05). Moreover, fragrant tea samples from three different areas were distinguished successfully using partial least squares discriminant analysis model (R2Y = 0.832 and Q2 = 0.625) which was established based on the relative contents of aroma components. The distribution of 23 key aroma components among different areas was analyzed by a data processing software. The 12 most abundant aroma compounds identified in Songyang area included maali alcohol, 1-octen-3-ol, (E)-2-octenal, benzaldehyde, 2,3-epoxy-β-ionone, β-ionone, α-ionone, 2-pentylfuran, trans,trans-2,4-heptadienal, 3,5-octadien-2-one, trans,trans-3,5-octadien-2-one and 2-ethylfuran, β-linalool, α-cedrol, geraniol, nerol, methyl salicylate and Z-3-hexenyl benzoate were the most abundant aroma compounds in Suichang tea, and cis-β-ocimene, cis-3-hexenyl hexanoate, cis-jasmone, indole and naphthalene were found to be the most abundant in Wuyi area.

This study aimed to evaluate the quality characteristics of fresh straw mushroom (Volvariella volvacea) and straw mushroom chips produced by either low-temperature vacuum frying or vacuum freeze drying. The sensory attributes were evaluated and the contents of moisture, fat, soluble protein, polysaccharide and volatile flavor components were analyzed by chemical method and solid-phase micro-extraction combined with gas chromatography-mass spectrometry (SPME-GC-MS). Results showed that the hardness and brittleness of vacuum freeze dried chips were 5.965 kg and 1.881 mm respectively; they revealed a porous structure with large pores and their color and nutritional content were nearly identical to those of fresh straw mushroom. The nutritional content of low-temperature vacuum fried chips was significantly lower than that of fresh straw mushroom (P < 0.05) and the hardness and brittleness were 4.454 kg and 3.336 mm, respectively. They showed a loose internal structure and exhibited the typical color of fried food. In addition, the types and amounts of volatile flavor components varied between fresh straw mushroom and mushroom chips. A total of 27, 16 and 29 volatile flavor components were detected in fresh straw mushroom, vacuum fried chips and vacuum freeze-dried chips, respectively. The main volatile compounds in fresh straw mushroom were aldehydes (54.0%), ketones (40.27%) and alcohols (4.1%), which contributed to the delicate floral aroma and mushroom flavor. The main volatile compounds of vacuum fried chips, having a toasted flavor, were alkanes (79.83%), nitrogen and sulfur compounds (12.12%) and ketones (6.6%). Alkanes (81.07%), esters (8.54%) and nitrogen and sulfur compounds (7.9%) were the major components in vacuum freeze-dried mushroom chips, which contributed to the fruity aroma accompanied by toasted flavor. In general, the overall flavor of vacuum freeze dried chips was more diverse compared to fresh straw mushroom and vacuum fried chips.

In this study, the effect of boiling time on the flavor compounds of potato was investigated. The aroma constituents were extracted by solid-phase microextraction (SPME) and then analyzed by gas chromatography-mass spectrometry (GC-MS) combined with olfactometry. The results showed that 39, 26, 23, 21, 21 and 21 substances were detected in potato boiled for 30, 60, 90, 120, 150 and 180 min, respectively. With increasing cooking time, the yellowish color of potato became darker, accompanied by enhanced off-flavor. Meanwhile, the contents of hexanal, nonanal, trans-2-octenal, decanal, trans-2,4-heptenal, trans-2-nonenal, trans,trans-2,4-nonadienal, trans-2,4-decadienal and other substances, which contribute to the aroma of potato, were gradually decreased. The content of methyl thiopropanal, one of the characteristic flavor compounds of potato, was not changed significantly with extended cooking time. However, because of the reduction of other key flavor substances, methylthiopropanal enhanced the overall flavor of overcooked potato.

A predictive model for rapid quantification of moisture and reducing sugar in fresh sweet potato was established by near-infrared (NIR) spectroscopy, which could facilitate the quality analysis and germplasm screening of sweet potato. In this study, 146 samples of different lines of sweet potato were selected, out of which 109 samples were used as calibration samples while the rest were used as validation samples. After different spectral pretreatments and optimal wavelength selection by synergy interval partial least squares, a principal component regression model and a partial least squares model were developed for predicting the contents of moisture and reducing sugar in sweet potato, respectively. The results showed that the coefficient of determination, root mean square error of prediction, and standard deviation ratio of the optimal model for moisture and reducing sugar contents were 0.974 and 0.885, 1.154 and 0.270, and 6.334 and 3.148, respectively, indicating that the two models have good prediction performance, and the NIR model predicted values had a good correlation with the corresponding chemical values. Therefore, the predictive model is suitable for rapid quantification of water and reducing sugar in large-scale sweet potato breeding.

Nitrogen-doped graphene oxide (NGO) was synthesized by a one-step hydrothermal method and characterized by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). A NGO modified carbon paste electrode (NGO/CPE) was prepared, and the electrochemical behaviors of capsaicin at NGO/CPE were studied. Experimental results showed that the voltammetric response of capsaicin at NGO/CPE was greatly improved when compared with bare carbon paste electrode (CPE). Some parameters such as NGO concentration, accumulation time and pH were optimized. Capsaicin was determined by using differential pulse voltammetry. Under optimal conditions, the peak current was linearly proportional to capsaicin concentration in the range of 5.0 to 1 200 μg/L, with a limit of detection (LOD) of 2.0 μg/L (RSN = 3). The proposed method was applied for the determination of capsaicin in hot pepper samples, and the results well agreed with those obtained by colorimetry.

α-tocopherol is a natural antioxidant and nutritional supplement and has been widely used in the food field. However, its scope of application is greatly limited due to its high susceptibility to environmental factors including oxygen, light and metal ions, ease of inactivation and water insolubility. In this study, α-tocopherol was encapsulated in chitosan nanoparticles (α-TOCCSNPs) by emulsification-ionic gelation method. To optimize the process, the average particle size (APS) and encapsulation efficiency (EE) were investigated as a function of chitosan (CS) concentration, α-tocopherol concentration, mass ratio of CS to sodium tripolyphosphate (TPP), pH and stirring speed by one-factor-at-a-time and orthogonal array designs. The CS nanoparticles were characterized by dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM) and evaluated for release pro?les and antioxidant properties in vitro in order to provide a theoretical basis for the application of α-tocopherol to inhibit lipid oxidation in cured meat products during storage. The results demonstrated that the optimal conditions for preparing α-tocopherol loaded CS/TPP nanoparticles were as follows: CS concentration, 1 mg/mL; mass ratio of CS to TPP, 7:1; pH, 4.5, and stirring speed, 900 r/min. The APS and EE of α-tocopherol loaded nanoparticles were 214 nm and 51.65%, respectively under the optimized conditions. The FTIR spectrum con?rmed that the encapsulation of α-tocopherol was achieved by electrostatic adsorption, and the SEM observation showed uniform average particle size distribution and regular spherical morphology. The α-tocopherol chitosan nanoparticles had sustained antioxidant activity in vitro.

Adhesion and agglomeration easily occur during the traditional drying process of sweet potato residue. In order to improve this phenomenon, the process parameters for the fluidized bed drying of sweet potato residue, i.e., material loading per unit area, bed temperature, air flow rate, were optimized using response surface methodology with a Box-Behnken design. The weighted average of dimensionless drying time and granularity was used as response variable. The results showed that the response was influenced in decreasing order by material loading per unit area, air flow rate and bed temperature. The optimal conditions obtained from the regression model were as follows: loading capacity, 5 264 g/m2; air flow rate, 52.73 m3/h; and bed temperature, 51.33 ℃. Under these conditions, the predicted response value was 0.790, and the validation experiments showed a prediction accuracy of up to 93.60%. Compared with traditional drying method, the time required for fluidized bed drying was shortened. Additionally, 82.3% of the dried product could pass through a 20-mesh sieve, bulk density of the sample was 0.446 g/mL, which was significantly increased by 25.8%, and hardness was 485.382 g, which was significantly reduced. Under scanning electron microscopy, it was observed that the fluidized bed dried product exhibited particles with larger internal voids and had a looser structure, leading to reduced comminution cost. This study may provide a theoretical basis for industrial drying, prolongation of the storage time and intensive processing of sweet potato residue.

The aqueous enzymatic extraction of safflower oil was optimized using factional factorial design and response surface methodology. The effects of processing parameters, including enzyme type and combinations, material to liquid ratio, total enzyme dosage, hydrolysis time, temperature and pH on oil yield were investigated. Results showed that a mixture of xylanase (UTC-X50), pectinase (NCB3/ZG-040) and alkaline protease (NCB3/ZG-002) (1:2:3, U/U) was the most efficient for the extraction of safflower oil and the optimum enzyme dosage was 197.36 U/g. The maximum yield of 84.68% was obtained after sequential hydrolysis with both xylanase and pectinase for 131 min at pH 4.2 and 50 ℃ with a material/liquid ratio 1:4, followed by alkaline protease at pH 9.8 and 40 ℃ for 60 min. Gas chromatography analysis revealed that the fatty acid profile of safflower oil obtained under the optimized conditions contained 78.27% linoleic acid, 12.61% oleic acid and 0.10% linolenic acid.

The effects of potato flour on the rheological properties and fermentation ability of pizza dough as well as the texture characteristics and sensory evaluation of pizza base were investigated. The results showed that potato flour addition increased the water absorption capacity of wheat flour and shortened dough development time despite reducing dough stability time and increasing softening degree. Meanwhile, the amount of potato flour added was negatively correlated with dough extensogragh parameters such as?resistance to extension, extensibility and stretchability. In addition, potato flour addition could improve dough fermentation ability and springiness, but increase the hardness and slightly decrease the sensory quality of pizza base. Taken together, the optimum amount of potato flour added to wheat flour was determined to be 15%. Using one-factor and orthogonal array design methods, the optimal formulation for pizza base was determined as follows: potato flour 15%, water 60%, and yeast 1.2%. The optimal processing parameters were as follows: proofing at 38 ℃ for 30 min with 75% moisture followed by baking at 200 ℃ for 15 min. Under these conditions, pizza base with the best sensory quality and a hardness of 4 166.493 g was obtained.

The trypsin-assisted extraction of polysaccharides from the muscle of cuttlefish (Sepia pharaonis) was optimized using one-factor-at-a-time method and response surface methodology. The in vitro antioxidant activity of the obtained polysaccharides was assessed and compared with that of those obtained by water extraction and alkali extraction. The optimum extraction conditions were determined as follows: hydrolysis temperature, 55 ℃; solid-to-water ratio, 1:40 (g/mL); hydrolysis time, 4 h; and trysin dosage, 2.5%. Under these conditions, the maximum polysaccharide yield of 4.15% was obtained, which was higher than those extracted with water and alkali. The antioxidant tests in vitro showed that the enzymatically extracted polysaccharide displayed higher antioxidant activity than the water- and alkali-extracted ones. At a concentration of 4 mg/mL, the percentage scavenging of hydroxyl radical by the polysaccharides extracted with water, alkali and trypsin were 50.15%, 55.14% and 89.47%, with median inhibition concentration (IC50) values of 4.51, 3.56 and 0.82 mg/mL, respectively; the percentage scavenging of DPPH radical were 28.89%, 31.48% and 40.80% with IC50 values of 16.66, 15.43 and 11.50 mg/mL, respectively; and the percentage scavenging of superoxide anion radical were 75.43%, 81.63% and 97.00% with IC50 values of 1.15, 0.69 and 0.29 mg/mL, respectively. The reducing capacity values of the three polysaccharides were 0.134, 0.156 and 0.193, respectively. Collectively, it was shown that the yield of enzymatically extracted polysaccharides was higher and the polysaccharides had higher antioxidant activity in vitro. The polysaccharides from the muscle of S. pharaonis have the potential to be a new non-hazardous and natural antioxidant.

The present study aimed to optimize the process parameters for the ultrasonic-assisted enzymatic extraction of total flavonoids from old leaves of Toona sinensis. Using one-factor-at-a-time method, enzyme dosage, pH, temperature, and solid to liquid ratio were identified as important factors affecting the total flavonoid yield. These factors were by response surface methodology. An HPLC method to determine total flavoids in T. sinensis was established. The results showed that the optimum conditions were as follows: hydrolysis with 0.6% cellulose at pH 4.6 and 45 ℃ for 120 min, followed by two cycles of 40 min extraction at 62 ℃ with 60% ethanol as the extraction solvent at a solid to liquid ratio of 1:25 (g/mL) under 140 W ultrasonic irradiation. Under these conditions, the total flavonoid yield was 14.98%, which was significantly increased compared with traditional enzymatic extraction. The results of HPLC showed that the flavonoids extracted contained 0.16% rutin, 0.06% quercetin and 0.03% kaempferol.

The microwave-assisted extraction of oil from Rana chensinensis eggs using anhydrous ethanol as the extraction solvent was optimized by one-factor-at-a-time method and response surface methodology. With this aim, we investigated the effect of solid-to-solvent ratio, soaking time and microwave power on the oil yield. The results obtained from the study showed that the optimized conditions were as follows: solid-to-solvent ratio, 1:9.82 (g/mL); soaking time, 3.33 h; microwave irradiation time, 30 min; and microwave power, 600 W. Under these conditions, the oil yield could reach (20 ± 0.67)%, which was higher than that obtained by other extraction methods. By gas chromatography-mass spectrometry (GC-MS), 27 fatty acids in the extracted oil were detected. Unsaturated fatty acids accounted for 54.98% of the total fatty acids in the oil, with 9-octadecadienoic acid, cis-11,14-eicosadienoic acid, 7,11,14-eicosatrienoate, 8,11,14,17-eicosatetraenoate, 9,12,15-octadecatrienoic acid, 9-hexadecenoic acid and 7,10,13,16,19-docosapentaenoate being predominant.

This study aimed to lower the water activity of ready-to-eat Scophthalmus maximus and consequently to prolong its storage life. Glycerol, sodium lactate and maltitol were used as water activity-lowering agents. The water activity-lowering effect of each of these compounds was determined by one-factor-at-a-time experiments. Combinations of the water activity-lowering agents were optimized by response surface methodology based on a three-variable, three-level Box-Behnken design. Furthermore, storage experiments were carried out on samples with and without water activity-lowering agents. The optimum combination obtained was 4.1 mL/100 g glycerol, 1.5 mL/100 g sodium lactate and 4.0 g/100 g gmaltitol. Under this condition, the water activity of the product with 40% water was 0.781. After seven days of storage at 37 ℃, total bacterial count was 4.04 (lg(CFU/g)), total volatile basic nitrogen (TVB-N) content was 12.47 mg/100 g, and thiobarbituric acid (TBA) value was 1.48 mg/100 g, which were all below the national standard limits. Accordingly, it was proved that the water activity-lowering agents could effectively improve the preservability of ready-to-eat Scophthalmus maximus and prolong its storage life.

In this study, the carboxymethylation of polysaccharides (LYP) extracted from longan (Dimocarpus longan) pulp was investigated using monochloroacetic acid (MCA) with polysaccharides-to-MCA ratio, reaction time and reaction temperature as independent variables. The degree of substitution (DS) was taken as response value to optimize the important reaction conditions by response surface methodology. Meanwhile, the antioxidant activity and immunoregulatory of carboxymethlated polysaccharides (CM-LYP) in vivo were measured. The results showed that the optimized conditions that provided the maximum DS of 1.053 were determined as follows: reaction time, 3.2 h; MCA concentration, 1.2 mol/L; and reaction temperature, 73 ℃. The antioxidant activity of CM-LYP was concentration dependent in a certain range of concentration. The percentage inhibition of hydroxyl and superoxide anion radicals, lipid peroxidation, red blood cell hemolysis induced by H2O2 were (42.35 ± 5.67)%, (51.91 ± 5.34)%, (67.91 ± 5.72)%, and (47.23 ± 3.5)% by LYP, and (84.39 ± 4.47)%, (87.91 ± 7.32)%, and (79.85 ± 2.92)%, and (54.66 ± 2.83) % by CM-LYP, respectively, implying that the antioxidant activity of LYP was improved as compared to the native polysaccharides. The immunoregulatory activity in vivo showed that CM-LYP significantly improved spleen index in immunosuppressed, increased serum hemolysin level and lysozyme activity in serum and spleen, and maintained Th1/Th2 balance, and the effect was better than that of LYP.

This paper reports the optimization of the ultrasonic microwave-assisted extraction of water-soluble polysaccharides from tillering onion by one-factor-at-a-time method and response surface methodology. The response was polysaccharide yield. The optimum conditions were determined as follows: liquid-to-solid ratio, 17:1 (mL/g); ultrasonic power, 360 W; microwave power, 200 W; and irradiation time, 16 min. Under the optimized conditions, the polysaccharide yield was (11.92 ± 0.13)%. Solubility results showed that the extracted polysaccharide was soluble in water but insoluble in organic solvents. The results of color reaction experiments showed that the water-soluble polysaccharide did not contain starch or phenolic compounds but contained uronic acid. As indicated by ultraviolet-visible spectroscopy measurement, the water-soluble polysaccharide had no characteristic absorption peaks of nucleic acid and protein. Fourier transform infrared spectroscopy showed that the water-soluble polysaccharide had the characteristic absorption peak of polysaccharide. The weight average molecular weight was analyzed by high performance gel permeation chromatography. It was found that the water-soluble polysaccharide was not composed of homogeneous components.

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the simultaneous determination of background values of 4 hormones (testosterone, methyltestosterone, progesterone and hydrocortisone) in milk and chicken. The samples were hydrolyzed by β-glucuronidase and ultrasonically extracted with acetonitrile, and then the extract was defatted with hexane. The analytes were seperated on a ZORBAX SB-C18 column with methanol-0.1% formic acid as mobile phase by gradient elution. The mass spectrometer was run in multiple reaction monitoring mode (MRM) using positive- and negative-ion electrospray ionization (ESI), respectively. The quantitative analysis was carried out by matrix-matched external standard method. The results showed that the calibration curves had good linearity for 4 hormones in the tested concentration ranges, with correlation coefficients of more than 0.991. The limits of detection (LOD, RSN = 3) and limits of quantitation (LOQ, RSN = 10) were 0.02–0.10 and 0.06–0.33 μg/kg in milk, and 0.03–0.12 μg/kg and 0.10–0.40 μg/kg in chicken, respectively. The average recoveries at three spiked levels 56.0%–132.8% for milk and 79.6%–122.0% for chicken, and the precisions expressed as relative standard deviations (RSDs) were 1.8%–17.3% for milk and 2.0%–18.1% for chicken. The method proved to be simple, rapid, accurate, and suitable for rapid screening and detection of background values for 4 hormones in milk and chicken.

Terahertz time domain spectra for 40 flour samples with different contents of benzoyl peroxide were measured, and frequency domain spectra, refractive spectra and absorption spectra were obtained in the range of 0.2–2.0 THz. The time domain spectra indicated that the terahertz wave amplitude value of the flour samples with benzoyl peroxide was reduced as compared to reference signal, and the frequency domain signal was delayed to different degrees. The frequency domain spectra indicated larger amplitude and lower intensity of terahertz wave absorption for flour samples with higher content of benzoyl peroxide, demonstrating that benzoyl peroxide could reduce terahertz wave absorption in flour. The refractive spectra indicated that refractive index decreased gradually with the increase in frequency, but it increased with increasing content of benzoyl peroxide in flour. The absorption spectra indicated that benzoyl peroxide in flour samples had a significant characteristic absorption peak at 1.6 THz. Therefore, terahertz spectrum can be used for the identification of benzoyl peroxide in flour. Partial least squares (PLS), support vector regression (SVR) and least squares support vector regression (LS-SVR) were used separately to establish a calibration model by using the absorption spectral data of 40 flour samples as input variables. The determination coefficients (R2) of both the PLS and SVR models were lower than 0.9, with relative standard deviations (RSD) greater than 10%, while the R2 of the LS-SVR model was 0.986, with RSD of 4.30%, indicating that terahertz spectroscopy can be used to detect the content of benzoyl peroxide in flour.

An alternative method based on an off-line solid phase extraction (SPE) combined with large volume injection-gas chromatography-flame ionization detection (LVI-GC-FID) was developed to determine mineral oil saturated hydrocarbons (MOSH) in infant formula. The MOSH in samples were extracted with n-hexane. The extract was purified by solid phase extraction (SPE) on a column packed with silica gel impregnated silver nitrate and the optimal SPE cartridge was 5 mL glass syringe as indicated by comparison of different length to diameter ratios. Five milliliter of the pooled eluate was concentrated and then injected into the LVI-GC-FID system. The PTV parameters were as follows: the initial temperature was set at 45 ℃ and held for 1 min (split ratio was 200:1), then increased to 360 ℃ at a linear gradient of 250 ℃/min and held for 27 min (split valve was closed for 2 min followed by split ratio of 100:1). The GC column was heated from 35 ℃ (3 min) to 350 ℃ at 25 ℃/min, and then raised to 370 ℃ (10 min) at 5 ℃/min. FID temperature was set at 380 ℃. The GC injection volume was 40 μL. The calibration curve of paraffin oil was linear in the range of 2–500 mg/kg with correlation coefficient of 0.999. The quantification limit (LOQ) of MOSH in infant formula was 0.05 mg/kg. The recoveries from spiked samples were between 92.62% and 102.86%, with relative standard deviation (RSD) of 0.85%–2.57%. This procedure was applied to analyze MOSH in 10 commercial infant formula samples and the contaminant levels ranged from 0.24 to 1.30 mg/kg (0.12-0.85 mg/kg of MOSH between C16 and C35). The results suggested that it is necessary to routinely detect mineral oil contamination in infant formula for infant health.

A multi-residue method based on high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed for the quantitative determination of abamectin, ivermectin and emamectin benzoate in grouper plasma, muscle and liver. The target analytes were extracted with acetonitrile and then cleaned up with an alkaline alumina column/LC-C18 SPE column. The analytes were separated on a Thermo Hypersil Gold C18 column by gradient elution with 0.1% formic acid-10 mmol/L ammonium acetate as mobile phase A and acetonitrile as mobile phase B, and detected by multiple reaction monitoring (MRM) with electrospray ionization (ESI) under positive ion mode. The target compounds were quantified by the matrix-matched external standard method. Both pesticides could move into water through various environmental routes. Therefore, the bioaccumulation and elimination of avermectin and ivermectin in groupers were studied by bath administration at the upper and lower concentration limits (4 and 8?ng/mL for avermectin, and 6 and 12 ng/mL for ivermectin) in environmental water. Meanwhile, the food safety risk of the pesticide residues in fish was assessed. The results showed that the calibration curves were linear (R2 > 0.99) in the concentration range of 2.5–200?ng/mL for abamectin and ivermectin and 0.25–20?ng/mL for emamectin benzoate. The limits of detection (LOD) for abamectin, ivermectin and emamectin benzoate were 2.5, 2.5 and 0.25 ng/mL in plasma, 1, 1 and 0.1 μg/kg in muscle, 2.5, 2.5 and 0.25?μg/kg in liver, respectively. The limits of quantification (LOQ) were 5, 5 and 0.5 ng/mL in plasma, 2, 2 and 0.2 μg/kg in muscle, 5, 5 and 0.5?μg/kg in liver, respectively. The average recoveries at three spiked levels ranged from 74.6% to 93.6%. Intra-day and inter-day relative standard deviations (RSDs) were 2.3%–10.9% and 9.2%–12.6%, respectively. Abamectin and ivermectin were no-bioaccumulative substances and their elimination processes in grouper conformed to a first order kinetics equation. Under the conditions of this study, drug concentration was an important factor affecting the residual drug concentration and elimination time in grouper muscle tissues. Gouper was safe for consumption 22 and 39 days after 72 h bath administration for 4–8?ng/mL abamectin and 6–12 ng/mL ivermectin, respectively.

In order to study the pattern of cefotaxime metabolism in chicken plasma, an ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was successfully developed for the simultaneous determination of cefotaxime and its metabolite desacetylcefotaxime. Cefotaxime at a dose of 10 mg/kg was administered to laying hen, and chicken plasma was collected at different time points to quantitate cefotaxime and desacetylcefotaxime by UPLC-MS/MS. The results showed that the limits of detection (LOD) for cefotaxime and desacetylcefotaxime were 0.07 and 0.14 μg/L, respectively; the limits of quantification (LOQ) were 0.23 and 0.99 μg/L, respectively. The recoveries of cefotaxime and desacetylcefotaxime ranged from 86.7%–95.2% and 89.5%–112%, respectively, with relative standard deviation (RSD) less than 7.7%, which met the requirements for quantitative analysis. Cefotaxime was rapidly distributed in laying hens and reached the peak (56.34 mg/L) immediately after administration, and the rate of cefotaxime metabolism was fast, which was detected at a level lower than 3.0 μg/L after 24 hours. The main metabolite deacetylcefetaxime reached its peak (10.22 mg/L) after 45 min, and it was eliminated at a relatively slow rate was and was still as high as 54.0 μg/L at 24 h after administration.

Objective: To establish a nano-gold capillary immunochromatographic assay (CICA) based on a combination of colloidal-gold labeling and Immunochromatography for the rapid field detection of enrofloxacin (EF) residues in aquatic products. Methods: Based on the principle of indirect competitive immunoreaction, the CICA method was developed by optimizing antigen concentration in the test area, secondary antibody in the control area and gold-labeled antibody standard concentration. Then the sensitivity, specificity and repeatability of this method and several sample pretreatments were evaluated. Results: The visual and semi-quantitative detection limits for EF were estimated to be 5 and 1.29 ng/mL, respectively. The recoveries of EF in spiked negative samples of turbot, Spanish mackerel, tonguefishes, and Pacific while shrimp (P. vannamei) were 78.3%–129% and The intra- and inter-assay precision expressed as relative standard deviation (RSD) was less than 10%. Specificity analysis indicated that this method had strong specificity to all analogues except ciprofloxacin (CIP), for which the visual and semi-quantitative detection limit were 10 and 4.37 ng/mL, respectively and met the requirement of the national standard of China. Sulfonic acid extraction under normal temperature conditions was chosen as the optimal pretreatment method for CICA. Conclusion: CICA was a simple, rapid, easy-to-operate and reproducible method and could provide a new approach for the detection of antibiotic residues in aquatic products. Meanwhile, the pretreatment method for CICA chosen in this study can provide a theoretical basis and technical support for other rapid detection methods.

Objective: This study aimed to establish a real-time PCR method for rapid detection of kidney bean components in Lotus seed paste product. Methods: Specific primers and probes were designed based on the highly conserved region of the pvsbe2 gene of Phaseolus coccineus L. Specificity was confirmedDNA amplification of lotus seeds and other starch-rich plants. In addition, 1 ng/μL DNA of kidney bean was gradually diluted to determine its sensitivity. The DNA template of a mixture sample which contained 1% kidney bean and lotus seeds was 10-fold diluted to verify the weight sensitivity. And this method and PCR were applied to determine market samples for further validation. Results: This method had a high specificity which displayed no cross reaction with lotus seeds and other starch-rich plants. The sensitivity for detecting kidney bean DNA concentration and the proportion of kidney bean component were 1 pg/μL and 0.01%, respectively. The detection results indicated that positive amplification appeared in kidney bean present in lotus-seed-paste moon cake, which conformed to the food labels. Conclusions: The real-time fluorescent PCR method established in this study has the characteristics of high specificity and sensitivity and is suifor fast detection of kidney bean component in lotus seed paste products.