Peanut skin procyanidins were fractionated using?gel?permeation chromatography?with a?Toyopearl HW-40S column. Afterwards fraction 4, named PSP-4-1, was collected and further separated by preparative high performance liquid chromatography. As a result, we obtained a procyanidin monomer, procyanidin-4-1 (PSP-4-1). The structure of PSP-4-1 was identified by quadrupole-time of flight-liquid chromatography/mass spectrometry (Q-TOF-LC/MS) and nuclear magnetic resonance (NMR). Its inhibitory effects on acrylamide formation in a chemical model system and French fries were analyzed. The results showed that the structure of PSP-4-1 was epicatechin-(2β→O→7,4β→8)-catechin (procyanidins A1). It inhibited acrylamide formation in the chemical system and French fries in a nonlinear concentration-dependent fashion. In the chemical model system and French fries, the highest inhibition percentage of acrylamide formation was (58.10 ± 3.86)% and (57.16 ± 2.61)% at procyanidins A1 concentrations of 0.05 and 0.03 mg/mL, respectively. This study can provide a useful guideline for the development of a highly efficient and economical acrylamide inhibitor.

In this paper, the covalent cross-linking at an alkaline pH (pH 9.0) between different concentrations of anthocyanins and soybean protein isolate (SPI) was studied. The structure of the products was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), fluorescence spectroscopy and circular dichroism (CD) spectroscopy, and their inhibitory effect on lipopolysaccharide (LPS)-induced inflammation in RAW264.7 cell line was assessed. Results showed that the solubility of SPI decreased in the presence of increasing concentrations of anthocyanins and the quenching mechanism was a static process, showing a decrease in α-helix and an increase in β-sheet and random coil. The formation of super-macromolecular subunits was observed by SDS-PAGE in the presence of anthocyanins at 1.000 mg/mL. Besides, the addition of 0.167 mg/mL of the complex formed between SPI and anthocyanins at 200 μg/mL could markedly reduce the secretion of TNF-α and nitrite oxide (NO).

In the current work, low molecular mass dextran (with a molecular mass of 5 400 Da) was oxidized by NaClO-NaBr in a basic environment. The content of carboxyl groups gradually increased from 0.05% to 0.8% with increasing oxidant dosage. HPLC analysis indicated that dextran was degraded during the course of oxidation. Moreover, the degree of oxidation gradually increased with the increase of NaClO dosage, whereas the oxidized products were partly degraded into oligosaccharides when the dosage of NaClO was excessive. During the oxidation process the crystalline structures were gradually transformed into amorphous states. Structural characterization by 13C nuclear magnetic resonance (NMR) demonstrated that NaClO-NaBr oxidized the hemiacetal hydroxyl groups at the C1 position and other C positions of the glucose ring into carboxyl groups. This modification improved dextran solubility and the oxidized dextran exhibited good thermal stability. The oxidation of the hydroxyl groups of dextran into carboxyl groups under basic condition and the resulting changes in the physicochemical and structural properties of dextran provide a foundation for the oxidative modification of polysaccharides.

The aims of this work were to establish and optimize the phosphorylation reaction conditions of parvalbumin (PV), the major allergen of silver carp (Hypophthalmichthys molitrix), and to determine the influence of phosphorylation reaction on the structural and immunological properties of PV. Phosphorylation of PV was carried out by dry heating of its mixture with D-glucose-6-phosphate disodium salt hydrate (G6P-Na2) under varying conditions of mass ratio between reactants, reaction time and temperature. The type of polymerization was determined by tricine-SDS-PAGE, and the antigenicity was detected by dot blotting. The microstructure of the obtained polymer was examined by scanning electron microscope (SEM), and its secondary structure and surface hydrophobicity were measured by circular dichroism (CD) spectroscopy and the hydrophobic fluorescence probe 8-anilino-1-naphthalenesulfonate (ANS), respectively. The results indicated that the optimal conditions for phosphorylation reaction of PV were as follows: reaction temperature, 80 ℃; reaction time, 80 min; and ratio of PV to G6P-Na2, 1:4. The aggregate formation and the changes in the secondary structures of G6P-Na2-PV might explain the decrease of PV antigenicity after the phosphorylation reaction. Our present work strongly suggested an effect of phosphorylation on reducing the antigenicity of food allergens.

In this study, the antioxidant activity of α-tocopherol in soybean oil, palm oil, tea seed oil (Camellia oleifera Abel.) and lard was investigated under Rancimat test (110–130 ℃) and oven heating (120–180 ℃) conditions. α-Tocopherol loss and its effect on the total oxidation value of oils and fats were determined as well. The Rancimat test results showed that the addition of α-tocopherol (200–1 000 mg/kg) could concentration dependently significantly prolong the induction period (IP) of lard, and tea seed oil at 110 ℃ (P < 0.05), while the IP of soybean oil was negatively correlated with the concentration of α-tocopherol added. The oven test results showed that α-tocopherol loss was positively correlated with the heating temperature but negatively correlated with α-tocopherol addition. α-Tocopherol (1 000 mg/kg) could inhibit the increase of total oxidation values (TV) of soybean oil, tea seed oil, and lard at 180 ℃. On the other hand, the addition of α-tocopherol (500–1 000 mg/kg) showed a pro-oxidant effect in palm oil.

The in vitro simulated digestion of soybean protein isolate (SPI)-anthocyanin complexes with pepsin was carried out to investigate the effect of anthocyanin on protein digestibility, structure, subunit composition and molecular mass distribution were investigated during the digestion process. The results demonstrated that SPI was significantly digested in 30 min, and the protein digestibility of the control finally reached 48.5%. Furthermore, the addition of anthocyanins inhibited protein digestion. Anthocyanins inhibited 11S globulin digestion but promoted the degradation of 7S globulin α-subunit, one of the major soybean allergens, thus likely reducing the allergenicity of SPI. Size exclusion chromatography showed that the protein macromolecule was hydrolyzed into small molecular peptides, and the addition of anthocyanin inhibited the formation of small molecular peptides. The molecular mass distribution of the final products was mainly concentrated in the range of 3–100 kDa. Circular dichroism spectrum showed that anthocyanins changed the conformation of SPI; α-helix content gradually decreased and the contents of β-sheet and random coil while β-turn content changed irregularly. Fluorescence spectroscopy showed that anthocyanin increased the λmax and had fluorescence quenching effect on SPI. This study has clarified the mechanism of SPI dissociation from SPI-anthocyanin complexes, which will provide theoretical guidance for the preparation of easily digestible, highly absorbable, low allergenic protein products and well balanced nutritious diet in the field of food processing.

In order to investigate the effect of oxidative modification with reactive aldehyde on the structural and emulsifying properties of walnut protein, acrolein (0–1 mmol/L) was selected as a representative secondary byproduct of lipid peroxidation induced by lipoxygenase (LOX) for incubation with walnut protein. The results showed that the carbonyl content of walnut protein significantly increased from 4.287 to 11.078 nmol/mg with increasing aldehyde concentration, accompanied by a decrease in free sulphydryl and total sulphydryl by 55.18% and 31.13%, respectively suggesting that acrolein caused significant changes to walnut protein. The solubility of walnut protein decreased by up to 84% with the increase in its degree of oxidation, and the surface hydrophobicity declined from 469.47 to 412.22; the contents of α-helix and β-sheet increased, while the contents of β-turn and random coil decreased. In addition, the emulsifying capacity and emulsion stability of walnut protein decreased from 46.87 to 9.86 m2/g and from 25.93 to 17.63 min, respectively. All of these results indicate that acrolein can lead to oxidative structural modification of walnut protein, thus causing damage to the emulsifying properties of the protein.

The emulsifying activity index (EAI) and stability of soybean protein isolate (SPI)-stabilized emulsions containing water-soluble polysaccharide from soybean hull extracted by microwave-assisted extraction were investigated with respect to three variables: microwave power, irradiation time and solid-to-solvent ratio. The EAI of emulsions increased first and then decreased with microwave irradiation time, but always increased with increasing microwave power. The interaction between microwave irradiation time and solid-to-solvent ratio had a significant effect on the EAI. The absolute value of Zeta potential increased first and then decreased with the increase of microwave power. A microwave power of 480 W, an irradiation duration of 35 min, and a solid-to-solvent ratio of 1:20 (g/mL) were found to be the optimum conditions to obtain a higher EAI of 46.15 m2/g and a higher absolute value of Zeta potential of 34.3 mV compared to 16.31 m2/g and 21.5 mV observed for the SPI-stabilized emulsion without the polysaccharide extracted from soybean hull. The results of this study provide a basis for the industrial preparation of soybean hull polysaccharide to be used as an emulsion stabilizer.

This study designed a new anti-microbial peptide KWRRWQWRRWK-NH2 (KW-WK) with the fragment of bovine lactoferricin LFcinB18-28 as parent peptide. Apart from retaining the high charge and strong hydrophobicity of the parent peptide, arginine (R) and tryptophan (W) replacement was introduced to design this anti-microbial peptide based on the concept of symmetrical structure. The secondary structure, antibacterial activity, hemolysis activity, cell toxicity and stability of KW-WK were determined by circular dichroism spectroscopy, broth microdilution and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) method. The results showed that KW-WK existed in a random coil structure in aqueous solution. However, it was α-helical in the simulated environment of cell membrane. The minimal inhibitory concentration (MIC) of KW-WK ranged from 4 to 128 μmol/L, suggesting that its bacteriostatic activity was strong. The hemolysis rate was less than 5% when the concentration of KW-WK was 256 μmol/L. This result showed that its hemolysis activity was low. The therapeutic index of KW-WK was 9.14, and its cytotoxicity was relatively low. Thus, its cell selectivity was relatively high. In addition, after heat treatment 100 ℃ for 1 h, KW-WK still possessed rather high antibacterial activity. The enzymatic stability of KW-WK was greatly improved as compared to LFcinB18-28. Therefore, the new anti-microbial peptide KW-WK has shown a great application potential in the fields of food, medicine, livestock etc.

The effects of five different cooking methods (boiling, steaming, microwaving, oven baking and frying) on lipid and protein oxidation and their influence on the in vitro protein digestibility of sturgeon fillets were studied. Significant lipid and protein oxidative changes occurred in cooked fish fillets and were much more pronounced in roasted and fried samples. These changes were further reinforced during simulated digestion, especially intestinal digestion. A marked interaction between lipid and protein oxidation was also manifested during cooking and digestion. Furthermore, protein oxidation induced by cooking before digestion had a notable impact on proteolysis during digestion. Roasted and fried samples were less sensitive to pepsin due to polymerization of severely oxidized protein. After the completion of gastrointestinal digestion, there still existed some short peptides in cooked fish, especially roasted and fried fish, which could not be digested thoroughly.

Young tea leaves from four different cultivars (Yinghong 9, Fuding Dabai, Jinguanyin and Chuyeqi) at the same growth phase were subjected to suspended fermentation. By doing so, we aimed to evaluate the effect of different tea cultivars varying in the activities of polyphenol oxidase (PPO) and peroxidase (POD) and their ratio as well as catechin contents on theaflavin formation during the fermentation process. The results showed that the value of PPO/POD ratio was the highest in Fuding Dabai, followed by Yinghong 9 and Jinguanyin. Total simple catechins (TSC) and total ester-type catechins (TETC) were the highest in Yinghong 9, followed by Fuding Dabai and Jinguanyin, and Chuyeqi contained the lowest levels of TSC and TETC. All the catechins except (-)-gallocatechin gallate (GCG) and catechin gallate (CG) showed a rapid decline in the early stage of fermentation, and remained stable in the later stage. The catechins were dramatically consumed during the first 30 min of fermentation. The formation of theaflavins firstly increased, reaching a peak at 15 and 30 min and then decreased. Each theaflavin in fermented tea leaves from the various was found to differ in their peak time and height. In general, the amount of theaflavins produced during the fermentation of Yinghong 9, showing the second lowest PPO/POD ratio and highest catechin content was significantly higher compare with the other cultivars. Theaflavins were formed at the highest rate during the fermentation of Fuding Dabai and Jinguanyin, with the highest PPO activity. On the other hand, higher POD activity and lower catechin content resulted in the formation of less theaflavins. The lowest amount of theaflavins was formed during the fermentation of Chuyeqi, having the lowest PPO/POD ratio and lowest catechin content. Therefore, higher theaflavin formation was related to higher PPO/POD ratio, catechins content and TETC/TSC ratio.

Luteolin, quercetin and myricetin are natural plant flavonoids with similar structure and different numbers of hydroxyl groups. In this work, the mechanical and optical properties of fish scale gelatin edible films incorporated with luteolin, quercetin or myricetin were measured and compared with the aim of exploring the role of interaction between gelatin and flavonoids with different numbers of hydroxyl groups inside the composite films in improving the properties of the films. Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy showed that steric hindrance between gelatin molecules was formed by the addition of the flavonoids. In the meantime, hydrogen bonds and dipole-dipole force were formed between the hydroxyl groups of flavonoids and gelatin, and they were strengthened with the increasing number of hydroxyl groups. The interactions between the hydrophobic rings and hydroxyl groups of flavonoids and gelatin molecules led to the secondary structural transition from β-turn to β-sheet, random coil and α-helix. As a result of the strengthened hydrogen bonds and dipole-dipole force between flavonoids and gelatin molecules with the increasing number of hydroxyl groups, the molecular mobility of gelatin was weakened, making the film structure more compact and elevating the tensile extensibility. Although incorporation of flavonoids improved the ultraviolet absorbance, the number of hydroxyl groups did not affect the light transmittance of gelatin films. These results can provide a theoretical guideline for the improvement of gelatin edible films with the addition of flavonoids.

Ice structuring proteins (AISPs) were extracted from “Zhaodong” alfalfa hay into phosphate-buffered solution (PBS) followed by addition of ice spheres to bind AISPs, and their?anti-freeze activity?and?molecular?mass were determined.?Then AISPs were added into wheat flour before making dumpling wrappers and quick frozen dumplings. After several freeze-thaw cycles, the water-holding capacity of raw dumpling wrappers and the texture properties of raw and cooked dumpling wrappers were determined. The results showed that the relative molecular mass of AISPs was about 52 kDa and the thermal hysteresis activity was 0.54 ℃. The water-holding capacity of dumpling wrappers with added AISPs increased significantly with increasing number of freeze-thaw cycles. Both raw and cooked dumpling wrappers were kept homogeneous and stable and their textural properties were significantly improved with the addition of AISPs. Quick frozen dumpling wrappers with added AISPs showed no significant cracking. The scanning electron microscopic (SEM) characterization of quickly-frozen dumpling wrappers displayed that the surface structure of gluten network and starch granules were improved with the addition of AISPs, suggesting that AISPs can act as a cryoprotectant to improve the texture properties of quick frozen dumpling wrappers.

The objective of the present study was to purify and structurally identify hypoglycemic peptides from wheat germ protein. The protein was hydrolyzed with trypsin to obtain the hypoglycemic peptides, and the hypoglycemic effect was evaluated by animal test. The active peptides were obtained by ultrafiltration. The optimum resin was selected for purification of the peptides by ion exchange adsorption, and further purification was carried out by sequential column chromatography on SephadexG-25 and SephadexG-15 before separation by reverse phase-high performance liquid chromatography (RP-HPLC). Finally, the structures of the purified peptides were identified by HPLC-electrospray ionization-mass spectrometry (HPLC-ESI-MS). The results showed that the enzymatic hydrolysate had α-glucosidase inhibitory activity with an IC50 of 10.98 mg/mL, and could relieve symptoms in diabetic mice. The highly active peptides with molecular mass less than 5 kDa were obtained by ultrafiltration, and their IC50 was 1.60 mg/mL. 732 cation exchange resin showed the best separation efficiency, and the elution percentage with 2.5% ammonia was 98.13%. After ion exchange adsorption, the hypoglycemic activity was significantly improved, yielding an IC50 of 0.30 mg/mL. Eight peaks were obtained after purification by RP-HPLC and among these the amount and activity of peak 1, with an IC50 of 0.098 mg/mL, were both highest. HPLC-ESI-MS analysis showed that the abundance at m/z 274.45 was high and that 7 peptides including 1 dipeptide and 6 tripeptides were obtained by ion fragment re-assembling. The findings obtained in this work are of significant importance for the development of novel functional foods with hypoglycemic efficacy.

This paper studied the effect of adding different proportions (5%, 10%, 15%, 20% and 25%) of coix seed flour on farinograph properties, extensograph properties and gelatinization properties of wheat dough and texture properties and sensory evaluation of Chinese steamed bread. The results indicated that the addition of coix seed flour increased the contents of protein, fat and ash in wheat flour. Coix seed flour did not affect dough development time (DDT) or dough stability time (DST). The degree of weakening increased significantly when the addition amount of coix seed flour was greater than 15%. The tensile energy and the extensibility of dough generally decreased with the addition of coix seed flour. No significant difference was noticed between maximum tensile resistance at 45 and 135 min and the tensile ratio increased significantly. The addition of coix seed flour increased the hardness, elasticity and chewiness of Chinese steamed bread and reduced the recovery and cohesiveness, and the sensory evaluation was consistent with the results of hardness and chewiness. Coix seed flour added at 5%–10% had little impact on the sensory evaluation of Chinese steamed bread and the light flavor of coix was loved by consumers. Taking into account dough rheological properties, gelatinization characteristics and the quality of steamed bread, the appropriate addition of coix seed flour should be 10%.

A carbopol loaded-Surfactin antibacterial gel was prepared by using Surfactin as a major effective component, carbopol as a thickener and triethanolamine as a neutralizer. The formulation was optimized using response surface methodology with Box-Behnken design. Three dependent variables were considered: diameter of inhibition zone, pH and viscosity of the gel. The optimal formulation was determined as follows: Surfactin 0.60%, carbopol 0.35%, and triethanolamine 0.30%. The optimized gel was transparent and stable with effective antibacterial activity, and the disruption of mature Staphylococcus aureus biofilm by the gel was improved obviously as compared with sterile water. After being treated with the Surfactin gel, the biofilm showed lighter color and sparse distribution with a certain light transmittance and high disruption.

In this study, twelve strains of filamentous fungi were isolated from the infected Wallace melon. All the purified isolates caused the same disease symptoms when re-inoculated to healthy Wallace melon. The results of morphological characterization and rDNA internal transcribed spacer (ITS) sequence analysis showed that one strain of Epicoccum nigrum, one strain of Penicillium oxalicum, two strains of Alternaria Nees ex Wallr., three strains of Aspergillus Micheli ex Fr., and five strains of Fusarium LK. ex Fr. were isolated. E. nigrum was isolated for the first time from Wallace melon. In addition, new pathogens of Penicillium, Alternaria, Aspergillus, and Fusarium including P. oxalicum, Alternaria tenuissima, Aspergillus awamori, F. equiseti, F. verticillioides and F. avenaceum were also isolated.

Shewanella putrefaciens is a cold-adapted microorganism, which is considered as one of the most important species causing spoilage of sea foods. This study aimed to elucidate the molecular mechanism of the response to cold stress in S. putrefaciens. The differential expression of the proteome in S. putrefaciens DSM6067 at different temperatures (30, 10 and 4 ℃) was investigated using a label-free quantitative proteomic approach and two-dimensional liquid chromatography-tandem mass spectrometry (2D LC-MS/MS). The results showed that more proteins were expressed when the strain was cultured at lower temperatures. A total of 2 165 protein bands were obtained, 1 739, 1 761 and 1 832 of them being identified at 30,10 and 4 ℃, respectively. Bioinformatics analysis revealed that these proteins participated in several gene ontology (GO) categories and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. According to GO analysis, the functional categories were dominated by metabolic activity, catalytic activity, and molecular binding. Although the expression levels of proteins participated in fatty acid metabolism pathway were relatively lower in all samples among the whole metabolic pathways, there were significant differences in protein expression at different culture temperatures and the lower the temperature, the higher the expression level.

High-throughput pyrosequencing and the traditional culture method were used in this study to analyze the microbial community diversity in four samples of traditional fermented milk collected from south Xinjiang. Results showed that there were differences in the number and species of microbes isolated from the four samples when they were cultured on three media, i.e., MRS, YGC and Lee media. A total of 20 669 effective bacterial and 293 677 effective fungal sequences were obtained after quality control. Firmicutes was the dominant bacterial phylum in all samples with the highest abundance followed by Proteobacteri; Lactobacillus and Streptococcus were found to the dominant genera in the Firmicutes phylum. Ascomycota was the dominant fungal phylum followed by Basidiomycota; the genera Saccharomyces and Kluyveromyces were the dominant fungi belonging to the Ascomycota phylum. The results of this study can provide the basis for the exploitation and utilization of microbial resources in traditional fermented milk in Xinjiang.

In this study, we addressed the effects of exogenous addition of gamma-aminobutyric acid (GABA) and overexpression of glutamic acid decarboxylase (CsGAD) gene from Camellia sinensis on acid and cold stress tolerance in Lactobacillus lactis NZ9000. The results showed that exogenous addition of GABA had no significant beneficial effect on the biomass of L. lactis NZ9000 under both acid and cold stress. The CsGAD gene was obtained by reversed transcription PCR (RT-PCR) and cloned into the expression vector pNZ8148-CsGAD for efficient expression of GAD in L. lactis NZ9000/pNZ8148-CsGAD. The GABA synthesis ability of the recombinant strain was increased by over 5 times after 8 h of induction with nisin as determined by HPLC. Growth curves showed that under normal culture conditions, the recombinant strain reached the logarithmic phase of growth later than the control strain and the?maximum?yield of?biomass?at?the?stationary phase was 1.5 folds higher than that of the control strain. The control did not grow substantially at pH 4.0, while the recombinant strain remained viable. Under cold stress, the anti-freeze and survival ability of bacterial cells were higher in the late stationary growth phase than in the middle logarithmic phase and the early stationary phase. Moreover, the survival rate of the recombinant strain was 1 to 2 orders of magnitude higher than that of the control at each phase of growth. Taken collectively, the recombinant strain L. lactis NZ9000/pNZ8148-CsGAD had improved cold and acid stress tolerance due to GABA production from heterologous expression of CsGAD in it. The results of this study provide a basis for exploring the stress tolerance mechanism and improving the growth status of lactic acid bacteria for expanded industrial application.

This study aimed to reveal the structure of bacterial flora and dominant spoilage bacteria in adductors of the scallop Patinopecten yessoensis. The total bacterial flora of fresh and spoiled scallop adductors were analyzed via high-throughput sequencing of metagenomic DNA, as well as the culturable bacterial flora via high-throughput sequencing of total cultured colonies’ genomic DNA. The results based on metagenomic DNA showed that the diversity of bacterial flora in fresh samples was relatively high, among which, the genera with high relative abundance were Candidatus kuenenia (10.73%), Vibrio (8.15%), Aliivibrio (7.38%), Bacillus (7.20%) and unclassified (16.08%). The dominant spoilage bacteria at 4 ℃ were Photobacterium (46.91%), Aliivibrio (36.82%) and Pseudoalteromonas (11.01%). The dominant spoilage bacteria at 15 ℃ were Photobacterium (46.97%) and Aliivibrio (43.33%). The dominant spoilage bacteria at 25 ℃ were Photobacterium (41.94%), Aliivibrio (23.10%), Fusobacterium (18.61%) and Lactobacillus (10.60%). The results from cultured colonies’ genomic DNA sequencing revealed that the diversity of culturable bacteria flora in fresh samples, which was dominated by Pseudoalteromonas (89.46%), was significantly decreased. The culturable dominant spoilage bacteria during storage at 25 ℃ were Vibrio (50.98%), Shewanella (17.43%) and Lactobacillus (10.68%). The findings of this study can provide a basis for further investigating the mechanism of microbial quality?deterioration in adductors of P. yessoensis.

In order to reduce the ethanol content in wine, mixed-culture wine fermentations with Candida humilis and Saccharomyces cerevisiae were carried out using different inoculation methods (simultaneous inoculation and sequential inoculation) at two temperatures (13 and 23 ℃). The results showed that compared with the pure S. cerevisiae fermentation, the co-inoculation and sequential inoculation of S. cerevisiae with C. humilis could significantly enhance glycerol content and reduce ethanol yield during fermentation at 23 ℃, especially the sequential inoculation, which exhibited a 17.56% reduction (i.e., from (14.75 ± 0.23)% to (12.16 ± 0.59)%) in ethanol concentration (V/V) compared to the pure culture of S. cerevisiae. The co-fermentation generated more esters than the single strain fermentation, and especially the sequential inoculation increased the concentrations of total ethyl esters and ethyl acetate by 18.30% and 16.03%, respectively and ethyl butyrate concentration by 2.77 folds and significantly enhanced the floral and fruity aroma. As for fermentation at 13 ℃, the co-fermentation showed an increasing concentration of β-damascenone, and increased β-damascenone concentration by 26.19% with the simultaneous inoculation compared with the control. These results indicated that C. humilis had potential application for producing reduced alcohol wine when used in mixed fermentation with S. cerevisiae, which could provide a new tool for reducing alcohol level in wine production.

Objective: This study aimed to isolate a strain with high alkaline xylanase activity. Methods: The target strain was isolated with xylan as the only carbon source from the paper mill sludge. The xylanase activity was determined by the 3,5-dinitrosalicylic acid (DNS) method. The strain was identified based on physiological, biochemical and 16S rRNA gene sequence analysis. Results: The optimal pH of the xylanase enzyme was 8.0, and the optimum temperature was 50 ℃. The enzyme retained 87% and 85% of its initial activity at pH 10 and 80 ℃, respectively. It proved to be highly stable to both alkali and heat. The xylanase activity of the fermentation broth of the strain was 36.85 U/mL. Conclusion: This strain was identified as Microbacterium imperiale, which could produce a thermo-alkali-stable xylanase.

The aim of this study was to improve the detection efficiency of spoilage bacteria in Chinese rice wine. By using the traditional culture method based on sensory evaluation and the change in total acid, the target spoilage bacteria ZH-1 and ZH-2 were isolated from rancid Chinese rice wine. Furthermore, the spoilage bacteria were identified by their morphological and biochemical characteristics and 16S rRNA gene sequencing. Meanwhile, one-factor-at-a-time method and Box-Behnken design with response surface methodology were employed to optimize the culture conditions for the target spoilage bacteria. The results showed that the rancid Chinese rice wine was muddy with an off odor and increased total acidity. Both ZH-1 and ZH-2 were identified as Lactobacillus fructivorans. The spoilage bacteria grew slowly on solid medium, and it took as long as 9–10 days to culture them using the method described in GB 4789.35-2016; the optimal enrichment conditions for detecting L. fructivorans were MRS agar medium containing 0.08% L-Cys with pH adjusted to 5.4, addition of 9% (V/V) of anhydrous ethanol to the medium immediately before use, and culture temperature 30 ℃. The time required to detect quantitatively L. fructivorans using the optimized method could be shortened by 3–4 days.

The present study was intended to investigate the correlation between the three dominant microorganisms and aroma compounds of Baoquan fermented soybean paste. The volatile compounds of seven samples (BM1, BM2, BM3, BM4, BM5, BM6 and BM7) of fermented soybean paste artificially inoculated with pure or mixed cultures of the dominant microorganisms were identified by headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS). Furthermore, we also detected the volatile aroma compounds of these samples by an electronic nose and analyzed the sensor data by principal component analysis (PCA). The PCA results showed that the aroma of BM6 was most similar to the commercial product fermented for 34 d whereas BM7 was distinct from this product. The results of sensory evaluation and electronic nose analysis consistently indicated that BM6 was more acceptable to consumers. A total of 38 volatile compounds were identified, including 15 esters, 6 alcohols, 6 aldehydes and ketones, 3 acids and phenolics, and 8 other compounds. The esters and alcohols were derived from Zygosaccharomycse rouxii BSZ.16910 and the aldehydes and ketones from Staphylococcus epidermidis BSS.17312. There existed certain interaction between the three microorganisms on the synthesis of volatile compounds in Baoquan fermented soybean paste. Factor analysis demonstrated that S. epidermidis BSS.17312 and Z. rouxii BSZ.16910 made greater contribution to the generation of esters and alcohols.

Head-space solid phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS) was used to analyze the aroma components of Chinese yam chips prepared by four different drying methods. A total of 33 aroma compounds were identified. Among them, 13, 15, 11 and 14 aroma components were detected in Chinese yam chips dried by freeze-drying (FD), explosion puffing drying (EPD), vacuum drying (VD) and hot air drying (AD), respectively. These aroma components were mainly divided into aldehydes, nitriles, ketones, hydrocarbons, alcohols, acids, esters and others. Principle component analysis (PCA) was used to establish an aroma quality assessment model. The PCA loading and score plots revealed that FD dried chips showed the highest score and best aroma quality.

The volatile compounds of jujube flowers at different stages of maturity and jujube honey were extracted by solid-phase microextraction (SPME) and characterized by gas chromatography-mass spectrometry-olfactometry (GC-MS-O). SPME conditions were optimized. The main aroma compounds of jujube flowers were 2-ethyl butyrate, ethyl valerate, (E)-2-methyl-2-maleate, 3-enol ethyl ester, α-ocimene, 4,8-dimethyl-1,3,7-nonyl triene, α-farnesene, 2-methyl ethyl butyrate, 4-methyl-pentanoic acid ethyl ester, ethyl benzoate, lauric acid methyl ester, and 2-methyl cyclobutanone. The aroma descriptions of jujube flowers detected by GC-O were fruity, floral, sour and grassy. The aroma compounds in both jujube flowers and honey were (E)-3-hexen-1-alcohol, isooctyl alcohol, linalool, benzyl alcohol, acetic acid, hexanoic acid, octanoic acid, azelaic acid, lauric acid, myristic acid, palmitic acid, 2,6-methyl-1,3,5,7-octatetraene, phenol, methylis salicylas, methoxy phenyl oxime, naphthalene, and 3-cyanopyridine, which were mainly responsible for the characteristic jujube flower aroma of jujube honey.

The effect of different canopy thicknesses (70, 85 and 100 cm) under mechanical trimming systems on wine aroma characteristics of Cabernet Sauvignon was analyzed. The results showed that the canopy thickness of 70 cm significantly increased the contents of total phenols, tannins and total anthocyanins in wines, but inhibited the accumulation of aroma compounds. Besides, total concentrations of higher alcohols, fatty acids, aldehydes, ketones and volatile benzene derivatives were increased by the treatment of 85 cm canopy thickness. The odor activity values (OAVs) of 3-methyl-1-butyl, ethyl acetate, β-damascenone, benzene acetaldehyde, phenylethyl alcohol, isoamyl acetate and ethyl hexanoate, responsible for flowery, fruity and cheese aromas, were higher in wine from 85 cm canopy thickness treatment compared with the other canopy thicknesses.

Oils from Chinese sumac fruits collected from different areas were obtained by hexane extraction, cold pressing and hot pressing. The proximate components of Chinese sumac fruits were analyzed and the quality of the whole fruit oils was compared with that of the seed oils. The results showed the percentages of crude oil, crude protein and crude fiber in the whole fruits were 19.17%–19.62%, 8.87%–11.98%, and 25.20%–31.41%, respectively. The acid value and peroxide value of crude sumac fruit oil were 12.5–22.7 mg/g and 14.5–47.9 mmol/kg, respectively. It had a very deep color and was difficult to decolorize. The main fatty acids in the fruit oils were palmitic acid (25.92%–38.50%), oleic acid (14.77%–18.49%), linoleic acid (38.05%–54.30%), stearic acid (2.30%–3.26%) and α-linolenic acid (1.75%–2.56%). The content of vitamin E was 682.8–837.9 mg/kg and The contents of total flavonoids and sterol were 102.28–165.92 mg/100 mL and 37.28–108.07 mg/100 g, respectively. The contents of unsaturated fatty acids and linoleic acid (~70% and 54.30%) in the whole fruit oil were significantly lower than those (~90% and 74.08%) in the seed oil, whereas the content of palmitic acid (25.92%) showed an increase compared to 8.13% observed for the seed oil. In summary, there were large differences in crude oil quality and fatty acid composition between the sumac fruit and seed oils.

An ultra-performance convergence chromatography (UPC2) method was developed and validated for the determination of squalene in vegetable oils. The sample was dissolved in n-hexane, and analyzed directly after filtration. Optimum separation was achieved on a UPC2 HSS C18 SB column (3.0 mm × 100 mm, 1.7 μm) with gradient elution at a flow rate of 1.5 mL/min. Other parameters were set as follows: back pressure 12.4 MPa, column temperature 50 ℃, injection volume 1.0 μL, and detection wavelength 215 nm. The results showed that complete separation of the analyte was accomplished within 2.5 min, and the method had a good linearity in the range of 0.53-105.00 mg/L (r > 0.999 1). The recovery was between 86.97% and 102.41% with relative standard deviation ranging from 1.3% to 4.1% (n = 8). The limit of detection (RSN = 3) was 0.53 mg/L for squalene. The use of UPC2 with different sample pre-treatment methods to detect actual samples was compared with ultra-performance liquid chromatography (UPLC). The results showed that UPC2 was more efficient, faster, simpler and cheaper, which could be useful for the rapid and high throughput detection of squalene in oil.

The differences in the aroma components produced in buckwheat and wheat during fermentation by different starter cultures were analyzed by head space solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). The aroma compounds were identified based on their retention indices and mass spectra. A total of 38 aroma compounds were identified in unfermented buckwheat dough, and 80 and 63 aroma compounds in buckwheat dough fermented by yeast and lactic acid bacteria, respectively. A total of 11 aroma compounds were found to be present in unfermented wheat dough, and 42 and 17 aroma compounds in wheat dough fermented by yeast and lactic?acid bacteria, respectively. Accordingly, new aroma compounds were formed during the fermentation of both wheat and buckwheat dough and buckwheat dough contained a larger number of aroma compounds than wheat dough. Hydrocarbons (monoterpenoids and sesquiterpenes) and esters were the main aroma components in buckwheat dough both before and after fermentation by yeast, whereas esters were the main aroma components in buckwheat dough both before and after fermentation by lactic?acid bacteria. Hydrocarbon, esters, alcohols, acids, aldehydes and ethers were produced as the main aroma compounds during the fermentation of wheat dough by yeast, while a smaller number of aroma components including hydrocarbon, esters, aldehydes and ethers were produced during fermentation by lactic?acid?bacteria. Fermented buckwheat dough contained more aroma components. Both buckwheat and wheat dough showed a significant change in aroma composition after fermentation by yeast or lactic acid bacteria. Furthermore, the aroma composition changed with fermentation time.

To make full use of nutrients in shrimp heads and reduce the waste of resources, this experiment investigated the extraction of phospholipids from shrimp heads and the lipidomic analysis of phospholipid fatty acyl chains by multi-dimensional tandem mass spectrometry and gas chromatography. Ethanol was used as extraction solvent, and the optimized parameters were determined as follows: ethanol concentration 90%, extraction temperature 50 ℃ and extraction time 30 min. The extraction yield under these conditions was (11.58 ± 0.03) mg/g, which was 83.8% higher than that before optimization. The obtained phospholipids were esterified before analysis of fatty acyl chains by gas chromatography and were identified and quantified by high performance liquid chromatography-mass spectrometry in the negative-ion full scan mode. The results showed that the phospholipids contained 23 fatty acyl chains, including palmitic, linoleic, eicosapentaenoic and stearic acyl chain. The content of monounsaturated fatty acid chain was 9.51%, while that of polyunsaturated fatty acyl chain was 35.33%. A total of 28 phospholipids belonging to four classes (phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl inositol, and phosphatidyl serine) were detected in the phospholipid extract. The phospholipids obtained by this extraction method contained many highly unsaturated fatty acyl chains, such as 40:8, 36:7, 38:7, O-40:7, 40:7, 34:6, O-36:6, 36:6, O-38:6, 38:6, and 40:6. In conclusion, the abundant phospholipids from shrimp heads are highly worth developing and utilizing due to the high degree of unsaturation of their fatty acyl chains.

Purpose: To determine the optimal harvest time of Meili grapes in Yangling, Shaanxi province for processing of dry red wine. Methods: Grapes were picked regularly after the beginning of conversion for determination of physicochemical indexes, phenolic maturity and aromatic components. Grapes harvested at the optimal time for physicochemical and phenolic maturity were used for winemaking. The aroma composition and color parameters were measured during the fermentation process. Results: The grapes harvested on August 24 showed the best phenolic maturity with cell maturity index of 0.061 and seed maturity index of 0.521. The wine made from these grapes showed the most abundant aroma with 41 aroma components, whose total content was 471.75 mg/L. The brightness and red tone of the wine were also the most consistent with the quality requirements for dry red wines. The optimal harvest time for physicochemical maturity was 4 d later than that for phenolic maturity and resulted in a wine with inferior aroma and color. Conclusion: The quality of Meili wine with phenolic maturity was better than that of the other samples.

The volatile components of three types of Fenghuang Dancong tea were extracted using solvent assisted flavor evaporation (SAFE) and analyzed by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O). A total of 91 volatile components were identified by GC-MS, and 38 of them were common to all samples. Alcohols, ketones and hydrocarbon compounds were the major chemical classes, but there were significant differences in volatile components between the three samples. A total of 31 aroma-active compounds were perceived by GC-O, 30 of which were identified and found to mainly contribute to the floral, sweet, fragrant and fruity aroma. Linalool oxide I, nerol, linalool oxide II and nerolidol, which were abundant in all three tea samples and gave a pleasant aroma with relatively high odor intensity in GC-O, played an important role in the formation of aroma quality of Fenghuang Dancong tea.

Starch granule-associated proteins (SGAPs) from indica rice were isolated by sodium dodecyl sulfate (SDS) buffer from alkali washed rice flour and then identified by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Results indicated that the SGAPs from the top, middle and bottom starch layers mainly consisted of granule-bound starch synthase I (GBSS I), which slightly varied with respect to other components. Among these layers, the content of SGAPs in the middle layer was the highest, with GBSS I accounting for up to 99.8% and gluten accounting for only 0.11% of the total. Using the response surface methodology, the optimized conditions for SGAPs extraction from the middle layer starch were obtained as follows: SDS 10.90%, boiling time 4.10 min and MgSO4 0.90 mmol/L. Under these conditions, the yield of SGAPs was (1 028.61 ± 0.05) μg/g.

The purpose of this study was the optimization of the papain-catalyzed deproteinization conditions of polysaccharide from Portulaca oleracea L. (POP) by response surface methodology (RSM). Polysaccharide loss and the rate of protein removal were investigated with respect to four variables: enzyme to sample ratio, hydrolysis time, hydrolysis temperature and pH. The optimum operating conditions were obtained as follows: enzyme to sample ratio 0.2:1, hydrolysis time 60 ℃, hydrolysis temperature 3 h and pH 6. Under the optimized conditions, the deproteinization efficiency was as high as 78.22% with only 10.39% loss of the polysaccharide. Monosaccharide composition?analysis by high performance liquid chromatography (HPLC) showed that the purified polysaccharide was composed of mannose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose and arabinose in a molar ratio of 5.3:5.9:1.3:27.6:1:18.8:14.6.

A study of the microencapsulation process of Phyllanthus emblica L. (P. emblica L.) seed oil was carried out by the spray-drying method using gum acacia and maltodextrin as wall materials. The effects of emulsifier concentration, gum acacia/maltodextrin ratio, core/wall ratio and solid concentration on microencapsulation efficiency were investigated. As a result, The optimum conditions were obtained as follows: emulsifier concentration 1%, gum acacia/maltodextrin ratio 1:3.4 (m/m), core/wall proportion, 2:3 (m/m), and solid concentration, 14.2%. The highest microencapsulation efficiency obtained in this study was (90.74 ± 0.51)%. The scanning electron microscopy (SEM) images indicated that the microcapsules obtained under the optimum conditions were completely spherical and smooth. The oxidative stability of free and microencapsulated oils were tested under accelerated oxidative conditions by the Rancimat method. The results showed that the microencapsulated oil stored at 25 ℃ had a longer shelf-life (716 days) than the free oil (128 days). Thus microcapsules can apparently enhance the storage stability of P. emblica L. seed oil.

In order to provide an experimental basis for preparing collagen from the skin of Thamnaconus modestus, the conditions for enzymatic extraction of collagen from T. modestus skin with pepsin were optimized in this study, and we also analyzed the structure of the obtained collagen. A buffer pH of 3.0 for pretreatment, an enzyme dosage of 16 800 U/g, a solid-to-solvent ratio of 1:30 (g/mL) and a hydrolysis time of 21.5 h were found to be the optimum conditions to obtain a higher extraction yield of 27.6%. Amino acid analysis, UV spectroscopy, Fourier transform infrared spectroscopy, and sodium dodecyl sulfate-polyacrylamide-gel electrophoresis (SDS-PAGE) demonstrated that the collagen from T. modestus might be classified as type I collagen containing a unique triple helical structure.

Antioxidant peptides were prepared from highly denatured soybean meal by successive ultrasonic-assisted cellulase hydrolysis and protease hydrolysis in this study. The optimization of the process conditions was carried out using one-factor-at-a-time method and response surface methodology. The optimal conditions for ultrasonic-assisted cellulase hydrolysis were determined as follows: ultrasonic power 300 W, irradiation time 20 min, substrate concentration 8.36 g/100 mL, enzyme dosage 666 U/g, and pH 4.1. Under these conditions, the contents of soluble peptides and polysaccharides in the hydrolysate were (18.51 ± 0.36)% and (10.83 ± 0.32)%, respectively. The hydrolysate was then further hydrolyzed with alkaline protease, and the optimal hydrolysis conditions were obtained as follows: enzyme dosage 61 900 U, pH 9, hydrolysis duration 3 h, and temperature 56.4 ℃. The contents of soluble polypeptide and polysaccharide in the final product prepared under the optimized conditions were (25.47 ± 0.81)% and (13.22 ± 0.49)%, respectively. After purification by ethanol precipitation, DEAE-cellulose 52 ion exchange chromatography and Sephadex G-25 gel chromatography, the hydrolysis product was tested for antioxidant activity. The yield of purified antioxidant polypeptides was 2.18%. The ferric reducing power and superoxide anion radical scavenging capacity of the polypeptides at 1 mg/mL was determined to be (0.495 ± 0.042) mmol/g and (17.02 ± 0.22) U/g, respectively.

This study was concerned with the extraction, separation and purification of polysaccharides from pear pomace from juice processing and the analysis of their relative molecular mass, monosaccharide composition and structures. The results showed that a maximum yield of polysaccharides of 62.375 mg/g was obtained by ultrasonic-assisted extraction method under the following conditions: ratio of water to material 1:13 (g/mL), extraction time 60 min, ultrasonic power 132 W and extraction temperature 57 ℃. The best efficiency of protein removal from the polysaccharides was achieved using the Sevag method combined with papain; the process was easy to operate and time saving and led to maximum removal efficiency (75%) while reducing polysaccharide loss (24.71%). A maximum decolorization rate of 78.56% and a minimum polysaccharide loss of 25.86% were obtained by H2O2 treatment. A homogenous polysaccharide (LPB-C) was obtained after purification of the crude extract by DEAE-52 cellulose column chromatography. The viscosity average molecular mass of LPB-C was determined to be 8.47 × 104 g/mol, consisting of mannose, glucose, rhamnose and xylose in a molar ratio of 3.3:2.3:10.6:23.2. LPB-C was identified as a pyranoid polysaccharide containing beta glycosidic bonds. These results provide a basis for the development and utilization of pear pomace.

In order to monitor and assess the contamination level of Staphylococcus aureus in cold noodles, a total of 432 cold noodles samples were collected from supermarkets, street vendor stalls, restanuants and campus canteens in Yangling, Shaanxi Province and screened for S. aureus over one year. Of these, 105 samples (24.3%) were positive for S. aureus, and the S. aureus isolates were characterized by anti-microbial susceptibility testing and PCR for detecting nine enterotoxin genes (sea to sej). All the isolates were found positive for at lest one enterotoxin gene. The genes sea (96.2%) was detected in almost all the isolates, followed by see (64.8%), and seb and sec were also found in 57 (54.3%) and 52 (49.5%) and she in only one (1.0%) of these 105 isolates. On the other hand, sed, seg, seh, sei, and sej were not found. In addition, all the S. aureus isolates were resistant to at least one of 14 common antimicrobial agents and 90.5% of them were multiresistant to three or more anti-microbials. Resistance to penicillin and trimethoprim/sulfamethoxazole (each 100.0%) was most frequently detected, and all the isolates were sensitive to ceftriaxone, ciprofloxacin, vancomycin and amikacin. The multi-drug resistance to penicillin ampicillin, trimethoprim/sulfamethoxazole and amoxicillin/clavulanic acid (Pen-Amp-T/S-A/C) was detected in 65 (61.9%) of the 105 isolates and was identied to be the most predominant. Morever, all the isolates were spa typed. A total of 4 different spa types were detected among the 105 S. aureus isolates. The results showed that S. aureus spa-t701 (81.9%) was the most predominant clone, followed by spa-t441 (16.2%),while spa-t127 and spa-t796 were the lowest (each 1.0%). In summary, this study indicates that S. aureus isolated from cold noodles in chain supermarket, street food stalls, and strains have higher drug resistance and probability to carry enterotoxin genes. Morever, the dominant SPA types are t701 and t441. Thus, these findings can provide some theoretical guidance to regulatory authorities concerned.

The analytical methods of ultrasound-assisted solvent extraction (UASE) and solid phase micro-extraction method (SPME) coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS), respectively were developed for the determination of 5 substances of very high concern (SVHC), including N-methylaniline (NMA), N,N-dimethylphylamine (DMA), nonanal, butylated hydroxytoluene (BHT) and benzothiazole (BTZ) in food contact silicone products. These two methods were optimized and evaluated. The results indicated that the USAE-GC-MS/MS method was simpler and more efficient and had wider linear range, higher recovery and precision, which met the requirements of determination. This method was then employed to determine the contents of 5 SVHCs in 29 silicone nipples and 27 molds. The results revealed that the highest content of aldehyde in the nipples was 1 439.85 ng/g and the highest content of BHT in the molds was 4 828.78 ng/g; both NMA and DMA were detected from all samples analyzed. The difference in the contents of these SVHCs in the food contact silicon products was analyzed and their safety was evaluated based on their toxicity, and source and limit requirements. The contents of NMA and DMA were higher in the molds than in the nipples, which may be derived from the organic dye or other additives in the molds. Considering NMA and DMA may pose a risk to human health, the generation of anilines must be controlled by improving the formulation or the process. There was no significant difference in the content of nonanal between the nipples and the molds product. Furthermore, despite the high detection rate, it was still considered that the content of nonanal in the food contact silicon products was within the safe range. Migration experiments and exposure assessments should be carried out for BTZ and BHT in the future.

In this study, a rapid method using Fourier transform infrared (FTIR) and ultraviolet (UV) spectroscopies coupled with data fusion was established for the identification of five species of bolete mushrooms. The original spectra of 272 samples from different species were preprocessed and optimized by multiplicative signal correction (MSC) and second derivative (2D). The classification results from the original and the optimal data matrixes were compared. Then the single and fused spectral data were analyzed by partial least squares discriminant analysis (PLS-DA) and support vector machine (SVM). The results showed that 1) compared with the original spectra, the preprocessing methods of 2D and MSC could optimize the spectral information and improve the classification accuracy; 2) base on FTIR, UV, low-level data fusion and mid-level data fusion data matrixes, respectively, the prediction accuracy of the PLS-DA models was 86.87%, 66.67%, 78.89% and 95.56%, and the prediction accuracy of the SVM models was 88.89%, 74.44%, 91.11% and 100.00%, respectively, indicating that mid-level data fusion was better than the other methods; 3) in terms of the prediction accuracy, the classification ability of the SVM model with mid-level data was better than that of the PLS-DA model with mid-level data. In conclusion, the SVM model based on mid-level data fusion represents a rapid method for the effective identification of different species of bolete mushrooms. It can provide an effective method for identification and quality control of edible mushrooms.

Cu2O-reduced graphene oxide nanocomposite (Cu2O-RGO) was applied to modify glassy carbon electrodes (GCE) in order to determine dopamine (DA). The microstructure of the modified electrodes was characterized by scanning electron microscope (SEM) and X-ray differentiation (XRD). Then the electrochemical reduction conditions for preparing Cu2O-RGO/GCE and the experimental conditions for detecting DA were optimized. The electrochemical behavior of DA on the bare electrode and RGO or Cu2O-RGO modified electrodes was also investigated in pH 3.5 phosphate buffer solution (PBS) by cyclic voltammetry. The results showed that the oxidation peaks of ascorbic acid (AA), DA and uric acid (UA) could be well separated and the peak-to-peak potential separations between DA and AA and UA were 204 and 144 mV, respectively. Moreover, the linear response ranges for the determination of DA were 1 × 10-8–1 × 10-6 mol/L and 1 × 10-6 –8 × 10-5 mol/L and the limit of detection (LOD) was 6.0 × 10-9 mol/L (RSN = 3). The proposed method was further applied to determine DA in dopamine injections and serum with satisfactory results.

In order to study the quantitative structure-retention relationship (QSRR) between the chromatographic retention times and molecular structures of volatile organic compounds in drinking water, the molecular connectivity index, shape index, electrotopological state index and electrical distance vector of 56 volatile organic compounds were calculated based on their molecular structures and conjugation matrix. Further, the QSRRs between the retention times (tR) and seven structural parameters (0X, 1X, 2X, 3X, K1, E43 and M91) of these volatile organic compounds were developed. Using the structural parameters as the input variables of artificial neural network, satisfying QSRR models whose network structure was 7:4:1 were constructed by the back-propagation neural network (BNN) method. The total correlation coefficient rT was 0.999 1. The average relative error between the experimental and the predicted values (tR) was 2.17%, indicating good agreement. These results showed that there was a good non-linear relationship between the retention times and the seven structural parameters. This research would be helpful to quickly test the impact of water quality on the environment.

The purpose of the present study was to investigate the effect of chloride ion content on the contents 3-monochloro-1,2-propanediol esters (3-MCPD esters) and glycidyl esters (GES) during the deodorization of soybean oil. The chloride ion contents of the water source of steam used directly for the deodorization of soybean oil was analyzed. The deodorization was carried out by distillation with steams of different chloride ion contents and we determined the contents of chloride ion, 3-MCPD esters and GES in soybean oil before and after deodorization. The results showed that the chloride ion content in the steam increased with the increase of chloride ion content in the water, and the retention rate of chloride ion in the water was about 0.1%. When the content of chloride ion in the steam was increased from 1–10 to 50–200 mg/L, the content of 3-MCPD esters in deodorized oil was increased by 2.6 times, while the content of chloride ion in deodorized oil did not rise. Increasing chloride ion content in undeodorized oil resulted in increased contents of 3-MCPD ester and GEs after deodorization. The contents of 3-MCPD ester and GEs in deodorized oil were 4.49–7.84 and 14.88–19.84 mg/kg, respectively, when 0.5–5 mL of sodium chloride solution at a concentration of 100 mg/L (the final concentration in the oil was 1–10 mg/kg) was added before deodorization, which were 5.5–9.5 and 5.8–7.7 times higher than in undeodorized oil. Therefore, controlling or reducing the chloride ion content during the deodorization process plays an important role in reducing the contents of 3-MCPD ester and GEs in deodorized oil.

The polyclonal antibodies against gentamicin, kanamycin and apramycin were simultaneously coupled to CNBr-activated Sepharose 4B to make a composite immunoaffinity column (IAC). An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the simultaneous determination of the three aminoglycosides (AGs) in fish and shrimp with immunoaffinity column clean-up. The analytes were separated on a BEH Amide column（100 mm × 2.1 mm, 1.7 μm）utilizing gradient elution with a mixture of acetonitrile and 0.05% formic acid solution as the mobile phase. The analysis was carried out in the multiple reaction monitoring (MRM) mode using positive ion electrospray ionization (ESI). The column capacities of gentamicin, kanamycin and apramycin were 1 127, 1 368, and 925 ng/mL of gel, respectively. The optimum elution solvent was methanol containing 0.1% formic acid. The linear range of the method was 80.0–500 μg/L for gentamicin and 20–500 μg/L for kanamycin and apramycin, and the corresponding coefficients of correlation were all above 0.995. Recoveries from spiked fish and shrimp were in the range of 71.7%–96.8%, with relative standard deviations (RSDs) ranging from 4.2% to 10.9%. The limits of detection and the limits of quantitation were in the range of 10–40 and 20–80 μg/kg, respectively. The developed method would be a useful tool for monitoring aminoglycoside residues in aquatic products.

An ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the detection of the egg allergen ovalbumin in food in this investigation. Egg white was trypsinized and the resulting hydrolysate was purified by ultrafiltration, and then separated by Easy-nLC 1000 nano liquid chromatography-quadrupole/orbitrap high resolution mass spectrometry with acetonitrile-0.1% (V/V) formic acid water as the mobile phase. By comparison with the Uniprot database, the characteristic peptide GGLEPINFQTAADQAR(GR-16) with good specificity and sensitivity was selected. Then, the UPLC-MS/MS analysis was performed using positive ion electrospray ionization (ESI+) in the multi-reaction monitoring (MRM) mode. The method showed a good linear relationship in the concentration range of 5–5 000 ng/mL with a limit of quantification (LOQ) of 0.1 μg/g. The average recoveries ranged from 77.22% to 98.55% with relative standard deviations (RSDs) lower than 9.97%. This method has high specificity and good sensitivity and is also time-saving, and thus it can provide technical support for the accurate determination of egg allergens in food product.

An analytical method was established for rapid screening of 16 hormone residues in aquatic product by a modified Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) combined with ultra performance liquid chromatography-quadrupole time of flight mass spectrometry (UPLC-Q-TOF MS). The homogenized samples were extracted with acetonitrile containing 1% acetic acid, and the extract was desalted with sodium chloride and anhydrous magnesium sulfate, defatted with n-hexane and then cleaned-up on a C18 column. The analytes were separated on a BEH C18 column using a mixture of 0.1% formic acid and methanol as mobile phase by gradient elution and analyzed by MS using electrospray ionization (ESI) in positive ionization mode. The linear range was 1–100 μg/L for all compounds with correlation coefficients of more than 0.990 6. The recoveries of the hormones at three different spiked levels ranged from 53.6% to 135.2%, with relative standard deviations (RSDs) of 0.93% to 10.9% in Penaeus vannamei, Pseudosciaena crocea, grass carp and swimming crab matrices. The limits of detection (LODs) (RSN = 3) were in the range of 0.2–2.7 μg/kg and the limits of quantification (LOQs) (RSN = 10) for the analytes were 0.8–8.2 μg/kg. The method is simple, rapid, accurate and suitable for rapid screening of hormones in aquatic products samples.