The aim of this study was to elucidate the mode of action of a novel bacteriocin Lac-B23 from Lactobacillus plantarum B23, a small peptide with broad-spectrum antimicrobial activity, on Pseudomonas fluorescens. P. fluorescens was susceptible to bacteriocin Lac-B23 action, leading to the release of intracellular ATP and inorganic phosphate. Bacteriocin Lac-B23 first destroyed the extracellular membrane and then dissipated both transmembrane potential (Δφ) and transmembrane pH gradient (DpH), leading to the formation of channels in the cell membrane. Clear changes in the morphological integrity of P. fluorescens were observed under scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The cell membrane was destroyed, leading to the death of cells. Bacteriocin Lac-B23 could affect the network structure of the biofilm produced by P. fluorescens and exhibited anti-biofilm activity.

The aim of this experiment was to study the diversity of Bifidobacterium longum isolated from infant feces. Using modified MRS medium, bifidobacterial strains were isolated from the feces of healthy infants in Harbin. To identify and analyze the diversity of B. longum strains, we used physiological and biochemical experiments, 16S rDNA homology analysis, heat-shock protein 60 gene (hsp60) homology analysis, random amplified polymorphism DNA (RAPD) and multilocus sequence typing (MLST). Eighteen anaerobic strains were isolated, among which, 7 were identified as B. longum subsp. longum, and 3 as B. longum subsp. infantis according to morphology, physical and biochemical properties, 16S rDNA homology analysis and hsp60 homology analysis. The results of RAPD and MLST showed that the 7 strains of B. longum subsp. longum belonged to 6 genotypes while the 3 strains of B. longum subsp. infantis belonged to 2 genotypes. Overall, these results showed that there were differences in the diversity of B. longum isolated from infant feces.

The objective of this work was to analyze the changes in metabolites during the natural fermentation of apple into an enzyme drink. The pH value, total titrable acid, organic acids (lactic acid, acetic acid, and malic acid), sugars (sucrose, glucose, and fructose), alcohol, total phenolic content and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging ability were investigated. Results showed that pH value decreased from 5.05 to 3.88 while total titratable acidity and lactic acid increased gradually during the fermentation process. Acetic acid was accumulated from 0.018% to 0.23% during the process; malic acid increased from 0.67 g/L to 2.45 g/L during the first 14 days and then decreased slightly. Glucose and fructose increased until reaching their maximum of 130.6 and 177.2 g/L on the 21th day and then decreased, while sucrose kept decreasing to almost 0 g/L during the whole fermentation process. Alcohol was produced from the 14th to 21th day, reaching 6.6% on the 28th day. Both total phenolic content and DPPH radical scavenging ability increased continuously to their maximum values (259.4 mg/L, 90.9 %) on the 21st day followed by a decrease.

Three phase partitioning was used to extract and purify peroxidase (POD) from Lonicera japonica Thunb. The optimal conditions were obtained as follows: pH 5.60, ammonium sulfate concentration 39.49 g/100 mL, and ratio of crude extract to t-butanol (V/V), 1:1.38. Under these conditions, the activity recovery was 87.64% with a purification factor of 5.849, and the specific activity of purified peroxidase was 1 021.6 U/mg. By using three phase partitioning, 92% pigment was removed. Enzymatic properties revealed that the optimum temperature for this enzyme was 30 ℃ and the optimum pH was 5. The enzyme was stable in the temperature range of 10–40 ℃ and in the pH range of 4–7. In the presence of both guaiacol and H2O2, Michaelis constants (Km) and maximum reaction rates (vmax) of the enzyme were 8.12 mmol/L and 1.71 mmol/(min·L) for guaiacol, and 0.822 mmol/L and and 1.38 mmol/(min·L) for H2O2 at a fixed concentration of the other substrate, respectively. The affinity of the enzyme to various substrates was in the decreasing order: pyrogallol > catechol > bimethoxy aniline > guaiacol. The peroxidase activity was activated by Ca2+, Cu2+ and Zn2+ but inhibited by Mg2+, Mn2+, citric acid, ascorbic acid, L-cysteine, sodium sulphite and sodium metabisulphite.

In order to understand the applicability of endogenous proteases from squid liver as a rich source of proteases, the endogenous proteases of squid liver were identified and characterized with common carp myofibrillar protein as substrate by adding a variety of protease inhibitors. It was found that the degradation of myosin heavy chain (MHC) was significantly inhibited by addition of E-64, 1,10-phenanthroline and PMSF to the reaction system indicating that squid liver contained three kinds of proteases, metalloprotease, cysteine protease and serine protease. The cysteine protease had the best thermal stability and highest activity, which still maintained a high activity at temperatures higher than 50 ℃, and it could hydrolyze myofibrillar proteins into small molecules. Substrate specificity analysis indicated that the cysteine protease could only hydrolyze Z-phe-Arg-MCA, and was inhibited 100% by leupeptin and 99.4% by E-64, indicating that the enzyme consisted mainly of cathepsin L. At last, cathepsin L was purified to homogeneity by ammonium sulfate precipitation, ion exchange and gel filtration chromatography. The purified enzyme showed a molecular weight of about 25 kD.

This study analyzed the change of protein and its hydrolysate during the post-fermentation of Mucor-type douchi by SDS-PAGE and reversed-phase liquid chromatography (RP-LC). The correlation of free amino acid content with different chemical components and browning intensity was analyzed, and the extracellular enzymes from Mucor were semi-quantitatively detected by the API ZYM system. The results showed that the molecular weight of the final protein hydrolysate was mainly distributed in the range of 11–20 kD. The molecular weight of proteins was reduced rapidly at the early stage (from day 0 to 7), and the polypeptide composition changed greatly. The polypeptide content changed from day 7 to 42. The formation of free amino acids had the highest correlation with the total acid content with a correlation coefficient of 0.972, followed sequentially by the browning intensity and reducing sugar. Using the API ZYM system we detected 6 extracellular enzymes from Mucor.

Staphylococcal enterotoxin M (SEM) is a secretory superantigen encoded by the νSa genomic islands of Staphylococcus aureus. In this study, the sem gene from S. aureus without N-terminal signal peptide was subcloned into the prokaryotic expression vector pET-28a (+) to construct the recombinant plasmid pET-28a (+)-ΔNspsem and the recombinant expression plasmid was then transformed into E. coli Rosetta (DE3) competent cells. The positive clones, induced by IPTG, effectively expressed His-tag containing soluble ΔNspSEM fusion protein in E. coli Rosetta (DE3). The expression conditions including expression vector, time, IPTG concentration and temperature were optimized. Purified His-ΔNspSEM fusion protein was obtained by Ni2+-Sepharose affinity chromatography. Mass spectrometric analysis indicated that the amino acid sequence of the fusion protein was 96.3% similar to that of SEM. Circular dichroism revealed ΔNspSEM, whose 6 × His sequence was cleaved by thrombin, was rich in β-sheet (35%) and β-turn (21%) but low in α-helix (16%). The fluorescence emission spectrum of ΔNspSEM exhibited identical tryptophan emission peak (341 nm) with excitation at 278 and 295 nm. The time-dependent thermal stability of ΔNspSEM obtained at 100 ℃ by SDS-PAGE indicated that the recombinant protein had relatively high thermal stability. To conclude, our results showed that the ΔNspSEM recombinant protein was successfully expressed and that the purified protein exhibited a compact conformation similar to the natural one in solution, which can provide a basis for insight into the structure and function of SEM protein.

The single nucleotide polymorphisms (SNPs) in different serotypes of 7 specific targets for Salmonella detection were analyzed based on the whole genome sequences of 28 Salmonella strains (14 serotypes) published on NCBI. The results showed that S9 and S69 had more SNPs than any other target, making them a potential tool for Salmonella serotyping. Subsequently, the distinct nucleotide mutation sites of the two candidate molecular serotyping targets in different serotypes of Salmonella were analyzed. As a result, various combinations of the mutation sites were obtained for rapid molecular serotyping of 14 Salmonella serotypes, and the results showed that identical mutation sites existed in the same serovar, while different mutation sites were found in diverse serovars. Finally, 21 suspected Salmonella isolates were obtained by the national standard method from 192 food samples collected from supermarkets and open-air markets in Shanghai. The results of molecular serotyping by targets S9 and S69 were 100% consistent with the results of the traditional slide agglutination test; the Salmonella isolates were assigned to 4 different serovars, 10 strains of Salmonella Enteritidis, 7 strains of Salmonella Typhimurium, 2 strains of Salmonella Gallinarum and 2 strains of Salmonella Newport. The results of genome sequence analysis and strain serotyping showed that the combination of Salmonella-specific targets S9 and S69 had the potential for molecular serotyping of Salmonella, which is expected to be a time-saving and cheaper alternative to the traditional slide agglutination test and can provide a new idea for the application of PCR technology in Salmonella molecular serotyping.

In an effort to understand the effect of co-fermentation with Saccharomyces cerevisiae and Pediococcus pentosaceus at different ratios on the quality characteristics of Pucheng Chuantou steamed bread and hence obtain the optimal ratio, 5 steamed bread samples were made with combined starter cultures of Saccharomyces cerevisiae and Pediococcus pentosaceus at ratios of 10:1, 1.5:1, 1:1, 1:1.5, and 1:10, and their pH, texture and aroma were evaluated and compared with those of the sample made by the successor of intangible cultural heritage. The results showed that pH increased firstly and then decreased with increasing proportion of Pediococcus pentosaceus, reaching a minimum at a ratio of 1:1. The texture was evaluated by principal component analysis, and the overall sensory scores were established. It was found that better texture characteristics were obtained at ratios of Saccharomyces cerevisiae and Pediococcus pentosaceus of 1:10 and 1:1. The five steamed bread samples were diverse in flavor, and the highest number (15) of volatile aroma substances was detected from each of the steamed bread samples made with 1:1 and 1:10 mixtures of Saccharomyces cerevisiae and Pediococcus pentosaceus, with the former containing higher contents of ketones, alcohols, esters and acids. Overall, Chuantou steamed bread made with 1:1 mixture of Saccharomyces cerevisiae and Pediococcus pentosaceus was the best in terms of sensory evaluation, pH, texture and flavor.

The volatile compounds of Lu Mountain Clouds-Mist tea from three producing regions were investigated by headspace solid phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME-GC-MS). A total of 76 volatile components were identified from the samples, the predominant ones being (Z)-3-hexen-1-ol (4.00%), heptanal (3.87%), benzyl alcohol (13.76%), undecane (11.21%), linalool (3.70%), phenylethyl alcohol (14.41%), and cedrol (5.37%). Principal component analysis (PCA) was applied to find the main factors affecting the volatile components. The results showed that 6 principal components could reflect most of the information on Lu Mountain Clouds-Mist tea with a cumulative contribution rate of 82.63%. The tea samples from three different regions could be clearly discriminated based on their chemical properties. The geographical origin discrimination of tea samples collected randomly from a local market was also achieved by PCA. Lu Mountain Clouds-Mist tea from the same region could be identified with an accuracy of 100%.

In order to enrich nutrients in tartary buckwheat residue by liquid-state fermentation, the contents of protein, crude fat, minerals, crude fiber, ash, total flavonoids, total phenolics, amino acid composition and fatty acid composition in Xinong 9940 tartary buckwheat flour and its residue left after being subjected to liquid-state fermentation were analyzed and the antioxidant activity was evaluated by total reducing capacity, 1,1-dipheny1-2-picryl-hydrazyl (DPPH) radical scavenging, 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) radical scavenging assays. The results showed that protein, crude fat, ash, crude fiber, minerals contents of buckwheat residue increased significantly after fermentation. Furthermore, liquid-state fermentation did not change the amino acid and fatty acid composition of buckwheat flour. The total phenolic content of tartary buckwheat residue was 1 343.22?mg/100 g, which was significantly higher than that of buckwheat flour (559.76?mg/100 g), and the total flavonoids content was 2 186.06?mg/100 g, which was significantly lower than that of buckwheat flour (2 464.10?mg/100 g). Moreover, the contents of the flavonoids rutin and quercetin significantly decreased after fermentation. However, the total reducing capacity, DPPH radical scavenging capacity, and ABTS+· scavenging ability were significantly higher than those of tartary buckwheat flour. These results indicated that tartary buckwheat residue showed stronger antioxidant after fermentation.

The bitter-tasting compounds of essential oils from Zanthoxylum schinifolium Sieb.et Zucc grown in Hanyuan of Sichuan province, Anshun of Guizhou province (and its fractions separated by vacuum hydrodistillation) and Jiangjin of Chongqing municipality, and from Zanthoxylum bungeanum Maxim. grown in Hancheng of Shaanxi province were analyzed by sensory evaluation and GC-MS. A total of 20 essential oils from different species and geographical localities were subjected to evaluation of their bitterness thresholds and identification of bitter-tasting components and the results were verified by correlation analysis. The bitter-tasting components identified were further validated by addition of suspected bitter compound standards to fraction 1 of the essential oil of Anshun-grown Zanthoxylum schinifolium Sieb.et Zucc. Results showed that the bitterness threshold of essential oil varied among different Zanthoxylum species, with Zanthoxylum schinifolium Sieb.et Zucc being lower than Zanthoxylum bungeanum Maxim. The essential oil of Anshun-grown Zanthoxylum schinifolium Sieb.et Zucc was separated into four fractions with different bitterness thresholds. Correlation analysis of bitterness threshold with alcohols (linalool), ketones and their mixtures indicated that the bitterness had a highly significant correlation with ketones and a significant correlation with alcohols and that both classes of compounds synergistically contributed to the bitterness. High concentrations of alcohol gave bitter taste to the essential oil. Low concentrations of ketone or in a mixture with alcohol dramatically reduced the bitterness threshold of the essential oil.

Solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) were used to analyze the volatile flavor compounds of laboratory-made hurood during different fermentation stages. Sensory evaluation was conducted on huroods made in our laboratory and by herdsmen. A total of 66 volatile flavor compounds were identified during different fermentation periods, of which 45 were detected during the initial period (2–4 h) with the dominance of fatty acids, 27 were detected during the middle period (4–8 h) with alcohols and ketones being the predominant ones, and 44 were detected during the late period (from 8 h to the end), the predominant being ketones and benzenes. Sensory evaluation demonstrated that compared with that made by herdsmen, the laboratory-made hurood tasted more delicate, and was richer in milk flavor. The results of pH 4.6 soluble nitrogen quantification also confirmed this conclusion.

In this experiment, fluidized-bed enrichment of trace resveratrol in red wine was carried out by macroporous resin adsorption and hyperspectral images of the resin samples were acquired. The prediction models established using various spectral pretreatments were compared for obtaining the optimal algorithm. The results showed that the partial least squares regression (PLSR) model established by removing abnormal samples using Hotelling T2 test method, dividing the sample sets using the KS algorithm, and pretreating the spectral data using standard normal variate (SNV) method exhibited the best prediction performance with correlation coefficient of correction (Rc2), root mean square error of calibration (RMSEC), correlation coefficient of prediction (Rp2) and root mean square error of prediction (RMSEP) of 0.813 8, 0.047 7, 0.782 4, and 0.050 2, respectively. Hyperspectral imaging can provide a new method for detecting trace components.

Odorous compounds in the pulp and skin of finger citron fruits were analyzed by headspace solid-phase microextraction (HS-SPME) and purge and trap (P&T) with Tenax TA absorbent. A total of 44 and 45 odorous compounds were detected from the flesh (A) and peel (B) of Jinghua-grown finger citron (JFC) by gas chromatography-mass spectrometry (GC-MS), respectively. The results showed that HS-SPME and P&T method could be used complementarily in the identification of odorous compounds in finger citron fruits. Furthermore, 43 and 40 odorous compounds with high similarity were extracted by HS-SPME from A and B and detected by comprehensive two-dimensional gas chromatography combined with quadrupole-mass spectrometry (GC × GC-qMS), respectively. Additionally, there are 23 odorous compounds with odor activity value (OAV) > 1. The major contributors to JFC aroma were identified as limonene, linalool, terpinolene, α-pinene, β-pinene, myrcene, γ-terpinene, ethyl octanoate, geraniol, citral, leaf alcohol, etc. by partial least squares regression (PLSR).

Phenolic compounds from tea seed oil were extracted with 60% methanol and purified by sequential chromatography on silica gel and Sephadex LH-20 columns. The composition of purified phenolics was determined by RP-HPLC-DAD. Phenolic compounds with antiproliferative effect on HepG2 cells were identified by principal component analysis. The results showed that as one of the three fractions separated by Sephadex LH-20, Fr1 contained 5 phenolic compounds?including catechins (accounting for 62.60% of the total amount) and flavonoids. Fr2 mainly included phenolic acids and flavonoids; flavonoids represented 78.70% of Fr3. IC50 values of Fr1, Fr2, and Fr3 for the proliferation inhibition of HepG2 cells were 1.76%, 16.24%, and 12.35%, respectively. Principal component analysis showed that rutin and catechin were the major constituents in tea seed oil that had a significantly strong ability to inhibit cell viability.

This study adopted an automatic amino acid analyzer to measure the amino acid composition of whey proteins in human milk, bovine milk and goat milk. The nutritional value was comprehensively evaluated by the fuzzy recognition method based on ratio coefficient of amino acid (RCAA) and score of ratio coefficient amino acid ratio coefficient score (SRCAA). The secondary structure of whey proteins was measured based on the amide I and amide III bands in Fourier transform infrared (FTIR) spectra. Results showed that the ratio of essential amino acids to total amino acids (EAA/TAA) in goat whey proteins was 0.450, showing a 0.919 7 and 0.925 0 similarity to whole egg protein and United Nations Food and Agriculture Organization/World Health Organization (FAO/WHO) reference protein, respectively, and the SRCAA values were 68.47 and 76.56, respectively in the two patterns indicating high nutritional value. The proportion of α-helix structure in goat whey proteins was 20.26%, which is much closer to that of human whey proteins (27.37%) indicating greater ease of absorption by the human body. Therefore, goat milk is a better source of functional foods for infants and young children.

In this study, we addressed the effects of different cooking methods (boiling and steaming at a millet to water ratio of 1:20 and 1:1.5 (g/mL), respectively) on the vitamin, total phenolics and total flavonoids contents and antioxidant activity of Fenghonggu millet grown in Chifeng, Inner Mongolia. Compared with untreated millet, boiling and steaming resulted in a significant decrease in VB1, VB2 and phytic acid (P < 0.05). Additionally, boiled millet maintained a higher level of VB1, while steamed millet retained more VB2 and phytic acid. Boiled millet, rich in vanillic acid and cinnamic acid, retained a 1.39-fold higher total phenolic content than its steamed counterpart. The antioxidant activity measured by 1,1-dipheny1-2-picryl-hydrazyl (DPPH) scavenging, 3-ethyl-benzothiazoline sulphonic acid-6)ammonium salt (ABTS) scavenging, ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) assays was in the following order: raw millet > boiled millet > steamed millet. Therefore, boiling is a better way to cook millet.

Objective: To isolate and purify polysaccharides from the ink of Sthenoteuthis oualaniensis in the South China Sea, and to analyze the monosaccharide composition of the purified polysaccharides. Methods: Crude polysaccharides were isolated through water extraction followed by alcohol precipitation and passed through a solid phase extraction column to remove the pigment. The polysaccharides were fractionated and further purified into homogeneity by sequential chromatographies on DEAE-52 ion exchange and Sephacryl HR-300 columns. The monosaccharide composition was analyzed by ultra performance liquid chromatography (UPLC) after 1-phenyl-3-methyl-5-pyrazolone (PMP) derivatization. Results: Three purified polysaccharides designated as SIP1, SIP2, and SIP3 were obtained. SIP1 was composed of D-mannose, D-glucose, and D-galactose while SIP2 and SIP3 were composed of D-mannose, rat sugar, D-glucose, D-galactose and L-(-)-fucose in different ratios.

A method for simultaneously detecting 13 free monoterpene compounds in wine was established by liquid-liquid extraction coupled with gas chromatography with flame ionization detection (GC-FID). The monoterpene compounds in Cabernet Sauvignon and Merlot wines fermented by a commercial yeast strain SC or laboratory isolated Saccharomyces cerevisiae KDLYS9-16 from two wine producing areas in Shacheng and Changli, Hebei province, respectively were detected by this method. The results showed that the calibration curves exhibited a correlation coefficient (R2) of 0.996 7–0.999 3, and the limits of detection (LOD) varied between 0.580 and 1.073 mg/L. The recoveries were in the range of 89.98%–107.34% with relative standard deviations of 0.58%–3.18%. All four wines were higher in monoterpenes than grape must. The Cabernet Sauvignon dry red wine fermented by Saccharomyces cerevisiae KDLYS9-16 from Changli had the highest monoterpene concentration of 2.855 mg/L among the four wines, which was about 3.1 folds higher than that of grape must. Cabernet Sauvignon wine and must had a higher monoterpene concentration than Merlot wine and must. For both cultivars, the monoterpene concentration was higher in Shacheng must than in Changli must. The types and concentrations of monoterpenes in wine varied with cultivar. In conclusion, the established method in this study is simple, sensitive, and reproducibile and can be used for the detection of monoterpene compounds in grape and wine.

This study determined the contents of tea polyphenols, theanine, caffeine and lactic acid in non-fermented and Lactobacillus plantarum fermented black tea beverage by ferrous tartrate colorimetry, nihydrin colorimetry and alkaline titration. Four in vitro antioxidant models were used to study the antioxidant activity. Also, the major aroma components were analyzed by headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS). It was shown that after fermentation, the contents of tea polyphenols and caffeine in black tea beverage decreased slightly but theanine and lactic acid increased significantly (P < 0.05). Moreover, the scavenging capacity against some free radicals declined slightly. The GC-MS analysis showed that the contents of some volatile flavor components such as alcohols and ketone significantly increased after fermentation, contributing to enhancing the aroma quality of black tea.

Objective: To study the functional components from the kernel of Acer truncatum Bunge as a new food resource. Methods: The chemical constituents were isolated and purified by sequential chromatographies on silica gel, polyamide and Sephadex LH-20 columns and recrystallization. Electrospray ionization mass spectrometry (ESI-MS), 1H-NMR and 13C-NMR spectroscopic analysis were employed for the structural elucidation. Results: A total of twelve compounds were obtained and they were chemically identified as (7S,8R)-urolignoside (1), 1,2,3,6-tetra-O-galloyl-β-D-pyranglucose (2), 1,2,3,4,6-penta-O-galloyl-β-D-pyranglucose (3), quercetin (4), kaempferol-3-O-α-L-rhamnopyranoside (5), quercetin-3-O-α-L-rhamnopyranoside (6), quercetin-3-O-β-D-galactopyranoside (7), quercetin-3-O-α-L-arabinopyranoside (8), (+)-afzelechin (9), (+)-catechin (10), (-)-epicatechin (11), and daucosterol (12). Conclusions: All these compounds were identified for the first time in the kernel of this plant, while compounds 1, 2, and 9-11 were obtained for the first time from the genus Acer.

In order to understand the effect of different Lactobacillus species on the flavor characteristics of fermented dried radish, headspace solid phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS) was used to analyze the volatile flavor composition of radishes fermented by Leuconostoc mesenteroides (B1), Lactobacillus zeae (B2), Lactobacillus paracasei (B3), Lactococcus lactis (B4), Lactobacillus plantarum (B5) and Lactobacillus plantarum (L4), and naturally fermented control radish (C). A total of 77 volatile compounds belonging to 8 categories were detected in 7 samples, and 6 of these compounds were common to all samples, including phenylethyl alcohol, ethyl octanoate, ethyl caprate, ethyl nonanoate, ethyl heptanoate and isopentyl hexanoate. The types and relative?contents of volatile components in radish fermented by different strains were distinctly different. A total of 35 volatile compounds from 6 categories were found in B1 fermented radish, 25 from 6 categories in B2 fermented radish, 19 from 5 categories in B3 fermented radish, 30 from 7 categories in B4 fermented radish, 33 from 7 categories in B5 fermented radish, 31 from 6 categories in L4 fermented radish, and 37 from 7 categories in naturally fermented radish. The main volatile components in fermented radish were alcohols, acids, esters, aldehydes, ketones and olefins. Although naturally fermented radish contained the highest number of volatile compounds, many of them were detected at a lower level. The lowest number of compounds and lower contents were found in B2 and B3 fermented radishes. B1, B4, B5 and L4 could contribute to the formation of volatile compounds in fermented radish compared to natural fermentation. B1 could promote the formation of alcohols and alkenes, B4 could promote the formation of the alcohols, esters and olefins, L4 could promote the formation of ester, ketone and olefins, and B5 could promote the formation of alcohols, esters, ketones, aldehydes, and olefins.

The aims of the study were to identify and quantify the phenolic compounds present in extracts of Chinese olive fruit (Canarium album L.) and to investigate their respective antioxidant activities. A total of 12 phenolic compounds were identified in Chinese olive fruit by ultra-performance liquid chromatography (UPLC) coupled to time-of-flight mass spectrometry (TOF-MS). A quantitative method was established by UPLC coupled to triple quadrupole mass spectrometry (TQ-MS/MS) under the multiple reaction monitoring (MRM) mode. Phenolic compounds were separated within 15 min. The linearity (r > 0.98), limit of detection (LOQ) (< 1.436 ng/mL), limit of quantification (LOQ) (< 4.786 ng/mL), inter- and intra-day accuracy ( > 80.19%), precision ( > 1.12%) and recovery ( > 80.13%) of the method were all satisfactory and thus it could provide an efficient protocol to analyze phenolic compounds in fruit pulp extracts of Chinese olive. Quantitative analysis of different solvent extracts suggested that 3-O-galloylquinic acid and Geraniin isomers was the most abundant polyphenols in Chinese olive. Furthermore 80% acetone extract contained more polyphenols and possessed stronger antioxidant capacity.

Objective: To analyze the change of volatile compounds in the fermentation broth during the submerged fermentation of Antrodia camphorata and further to conduct statistical analysis. Methods: Headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS) was applied to qualitatively and quantitatively analyze the volatile compounds. Principal component analysis (PCA) and cluster analysis (CA) were adopted to completely evaluate the volatile components of A. camphorata. Results: At different stages of the fermentation process, A. camphorata showed different aroma profiles and a total of 50 compounds were identified, including 10 alcohols and 16 esters. PCA results showed that the cumulative variance contribution rate of the first two principal components was 62.786%, which could represent the main volatile compounds of A. camphorate. CA results showed that the changes of volatile compounds in the whole fermentation process could be classified into three categories. Conclusion: The volatile compounds produced during the submerged fermentation process of A. camphorata could be used as an important natural resource in the fields of cosmetics and foodstuffs. Furthermore, the comprehensive analysis of volatile compounds could provide an important technical tool for evaluating the quality and value of A. camphorata-related products and developing new products in the future.

The Soxhlet extraction of lipid from Antarctic krill was optimized using one-factor-at-a-time method and
response surface methodology. The lipid yield was studied as a function of solvent type and composition, extraction
temperature and time. The results showed that optimal extraction conditions that resulted in the maximum lipid yield
of 12.32% were as follows: a mixture of hexane and ethanol (3.5:1, V/V) as extraction solvent, temperature 80 ℃, and
time 5.4 h. Gas chromatography analysis showed that the lipid obtained was mainly composed of palmitic acid (C16:0,
28.86%), eicosapentaenoic acid (C20:5n3, 15.48%), oleic acid (C18:1n9c, 12.71%) and docosahexaenoic acid (C22:6, 12.22%).
The unsaturated fatty acid content was above 57.47%, with monounsaturated fatty acids and polyunsaturated fatty acids
accounting for 19.82% and 37.65%, respectively. Therefore, Antarctic krill is a novel source of polyunsaturated fatty acids,
and has high nutritional value and could be widely used as dietary supplements.

Wheat bran dietary fiber chewable tablets were produced by direct compression from dietary fiber (DF) rich wheat bran fermented by Pleurotus geesteranus with magnesium stearate and ultra-fine okra powder and added. The formulation of chewable tablets was optimized by response surface methodology with mass deviation, disintegration time, hardness and friability as responses. Meanwhile, the in vitro antioxidant properties of chewable tablets were evaluated. The results showed that the optimal formulation consisted of 64% fermented wheat bran, 34% ultra-fine okra powder and 2% magnesium stearate. The tablets produced revealed a smooth surface with uniform color and moderate hardness. The chewable tablets possessed strong antioxidant capacity in terms of anti-lipoperoxidation and hydroxyl radical scavenging capacity with IC50 values of 8 and 20 mg/mL, respectively. The formulation optimization antioxidant activity evaluation of wheat bran dietary fiber chewable tablets can provide theoretical support for the nutritional and functional value of the product

This study was conducted to evaluate the feasibility of conversion of isoflavones in soymilk using cellulose-immobilized β-glucosidase. β-glucosidase was immobilized onto cellulose particles with a loading capacity of over 40 mg of enzyme/40 cm3 carrier. The immobilized enzyme exhibited a significant efficiency for the conversion of 4-nitrophenyl-β-D-glucuronide (p-NPG) to p-nitrophenol. The optimal temperature for the enzyme was 50 ℃ and the Michaelis constant (Km) value was determined to be (1.38 ± 0.20) mmol/L. All isoflavones in black soymilk were completely converted to deglycosylated derivatives within 30 min using 40 cm3 of the immobilized enzyme as analyzed by high-performance liquid chromatography (HPLC). Experimental evaluation of the stability showed that immobilized β-glucosidase retained 60% of its original activity after 15 times repeated use and after 15 days of storage.

The optimization of the decolorization of crude oil extracted from Nannochloropsis oceanica, rich in eicosapentaenoic acid (EPA), was carried out using one-factor-at-a-time method and response surface methodology. Using a Box-Behnken design, a mathematical model was established indicating the effects of decolorizing agent dose, temperature and time on decolorization efficiency and oil recovery, respectively. The results showed that activated carbon exhibited the best decolorization efficiency. A decolorizing agent dose of 3.8 g/100 mL, a temperature of 68 ℃ and a decolorization time of 54 min were found to be the optimal conditions to obtain a higher decolorization efficiency of 98.05% and a higher oil recovery of 81.45% after three desorption cycles.

This study focused on the feasibility of using near infrared (NIR) spectroscopy for quantitative analysis of peanut milk. Simulated peanut milk samples were prepared by mixing different amounts of milk powder with peanut slurry and they were scanned by NIR. A quantitative analysis model was established based on the spectra obtained. The results demonstrated that the PLS modeling method could effectively make up for the light scattering and the interference between peanut and milk powder, and thus it could be applied to analyze such complex systems as peanut milk. The root-mean-square error of calibration (RMSEC), root-mean-square error of predication (RMSEP) and correlation coefficient (R) of the quantitative analysis model were 0.573%, 3.73% and 0.999 7 for peanut and 0.066, 0.183 g/L, and 0.955 7 for milk powder, respectively. In conclusion, NIR spectroscopy could be used in the rapid quantitative analysis of peanut milk. However, further study is needed on the model.

A rapid method was presented for the determination of 7 artificial dyes in plant extracts by ultra-performance liquid chromatography-electrospray ionization quadrupole orbitrap high-resolution mass spectrometry (UPLC-Q-Orbitrap-MS). Samples were extracted with water, and the extract was cleaned up on a polyamide solid phase extraction (SPE) column and separated by UPLC on a C18 column using a mobile phase consisting of 5 mmol/L ammonium acetate-acetonitrile with gradient elution. Data were collected by ESI Q-Orbitrap MS. The results showed that good linearity was observed in the concentration range from 10 to 500 μg/mL for all 7 artificial dyes, with correlation coefficients (r2) greater than 0.99. The limits of detection (LODs) ranged from 0.001 2 to 0.052 mg/kg. The average recoveries were in the range from 60.8% to 91.8% at 3 spiked levels with relative standards deviation (RSDs) between 2.1% and 6.5%. This method proved to be simple, time saving, accurate, reliable and sensitive and thus can be used for the fast screening and confirmation of artificial dyes in plant extracts.

Herein a novel colorimetric method based upon gold nanoparticles (AuNPs) was developed for the detection of lead in water. The method was based on the fact that the presence of glutathione (GSH) can prevent the aggregation of AuNPs at a high concentration of NaCl solution, while addition of Pb2+ to the solution will cause the aggregation of AuNPs, leading to changes in the color of AuNPs. Under the optimum conditions, the absorbance was found to be linearly proportional to the concentration of lead ion within the range of 10.36–1 036 ng/mL, with a limit of detection (LOD) of 2.072 ng/mL. The recoveries of Pb2+ from spiked samples were 99.1%–103.6%, and the precision expressed as relative standard deviation was less than 4%. Moreover, this assay showed good sensitivity, stability and reproducibility and thus could be used for rapid detection of lead ion in water.

A series of physical and chemical changes occur during the storage of eggs. In reality, the freshness of eggs is mostly measured by sensory evaluation. In this study, we tested the freshness of eggs stored under different conditions of temperature (4 and 25 ℃) and humidity (RH 75%, RH 85%, and RH 98%) by Haugh unit, egg yolk index, pH and impedance. The results showed good correlations of impedance with three other properties. The correlations were plotted, indicating that the freshness of eggs can be determined by using impedance values. The method could be performed simply and rapidly with accurate results, providing a promising tool for the detection of egg freshness in the egg industry.

Objective: To establish a method for the determination of β-phenylethanol in rice wine by solid phase extraction (SPE)-gas chromatography (GC). Methods: β-Phenylethanol was enriched from 3.0 mL of rice wine with an activated and balanced HLB solid phase extraction column, which was washed with 3.0 mL of water and 3.0 mL of methanol-water (4:6, V/V), and eluted with 3.0 mL of methanol. A gas chromatograph equipped with flame ionization detector (GC-FID) was used to analyze the target compounds. Results: In the concentration range of 10.1–202.0 mg/L, good linearity was achieved with a correlation coefficient (r) of 0.999 9. The limit of detection (LOD, RSN = 3) and the limit of quantification (LOQ, RSN = 10) were 0.9 and 3.0 mg/L, respectively. The recovery of β-phenylethanol was in the range of 95.5%?98.5%. The precision values expressed as relative standard deviations (RSDs) were 1.1%?1.4%. Conclusion: The method is simple, convenient, accurate and applicable to the determination of β-phenylethanol in rice wine and can effectively reduce the pollution of the gas chromatography system by rice wine matrix and prevent water in rice wine samples from bringing harm to the capillary column.

Purpose: A novel fluorescent quenching immune chromatographic strip (FQICS) using upconversion nanoparticles (UCNPs) was developed to detect sulfaquinoxaline (SQX) in milk samples based on the principle of fluorescence resonance energy transfer (FRET). Methods: UCNPs was prepared using a pyrolytic process, and colloidal gold was prepared using sodium citrate reduction method. Then OVA-UCNPs were distributed to the upper side to form C line. OVA-UCNPs and SQX-OVA coating antigen were added to the lower side of the NC membrane to form the T line. When a negative sample was added to the sample pad, the liquid sample containing colloidal gold-labeled antibody migrated via capillary action toward the end of the strip. When the mixture reached the T line, which was coated with SQX-OVA coating antigen and OVA-UCNPs, the gold-labeled antibody bound to SQX-OVA coating antigen. Since the UCNPs were simultaneously coated at the same location as the SQX-OVA coating antigen, the binding of gold-labeled antibody to SQX-OVA coating antigen could provide a suitable distance between the UCNPs and colloidal gold to cause FRET. Using a 980 nm laser, the test results could be evaluated visually according to fluorescence intensity. Results: The limit of detection (LOD) of this assay for SQX in PBS buffer was 1 μg/L, and the LOD for SQX in milk samples was 8 μg/L. The whole detection process could be completed within 15 min. Conclusion: The FQICS based on UCNPs allowed for simple, sensitive, time-saving, and rapid on-site detection of SQX residues in milk.

A method was established using high performance ion chromatography and pulsed amperometric detection for simultaneous analysis of 1-kestose (GF2), nystose (GF3), 1F-fructofuranosyl nystose (GF4), GF5, GF6, raffinose, stachyose and verbascose in infant formula milk powder. The chromatographic separation was achieved on a CarboPac PA20 column using a mobile phase composed of a mixture of sodium hydroxide and sodium acetate by gradient elution. Under the conditions optimized in this study, all the analytes were well separated, and the recoveries were 80.0%–103% with a relative standard deviation (RSD) less than 3% (n = 6). The method was rapid, accurate, reliable, and thus suitable for the determination of functional oligosaccharides in infant formula milk powder.

Beijing-you chicken is one of the precious local breeds in China. In the natural population, there are some multi-toed individuals because of the mutation of C-G base pair to an A-U pair at the 246 bp site in the LMBR1 gene. In this study, the genotype of multi-toed Beijing-you chicken was found to be different from that of Huadu Arbor Acres (AA) broiler, and the mutated base pair (A-U or C-G) was determined by PCR sequencing and restriction fragment polymorphism (RFLP) so that the breeds could be accurately discriminated from each other.

The uncertainty of measurement in the determination of iprodione residues in vegetables by high performance liquid chromatography (HPLC) was evaluated. According to the national metrology technical specifications JJF 1135-2005 (Evaluation of Uncertainty in Chemical Analysis Measurement) and JJF 1059.1-1999 (Evaluation and Expression of Uncertainty in Measurement), a mathematical model was established to evaluate the uncertainty for determining iprodione residues in vegetables. The sources of uncertainty that may be introduced were analyzed and each component of uncertainty was quantified and used to calculate combined uncertainty. The results showed that an expended uncertainty of 5.31 mg/kg (k = 2) was obtained for the determination of 0.40 mg/kg of iprodione in vegetables, and the preparation of standard solution, calibration curve fitting and measurement repeatability were the main sources of uncertainty.

A rapid method was developed for the simultaneous determination of chloramphenicol and erythromycin residues in aquatic products by high performance liquid chromatography-tandem mass spectrometry with solid phase extraction (SPE). Samples were extracted with acetonitrile and the extract was then purified by an Oasis PRiME HLB SPE cartridge. The analytes were detected in the multi-reaction monitoring (MRM) mode and quantified by the isotope internal standard method. The limits of quantification (LOQ) for chloramphenicol and erythromycin were 0.1 and 0.5 μg/kg, respectively. The average recoveries of the 2 analytes ranged from 86.7% to 102.6% with relative standard deviations of less than 5% in aquatic products (fish, shrimp and crab) at three spiked levels (n = 6). This proposed method was advantageous in routine detection of antibiotic residues in aquatic products for its simplicity and high sensibility.

This paper presents a method for the identification of diluted contaminants on the surface of chicken carcasses based on successive projections algorithm (SPA)-multiple linear regression (MLR)-receiver operating characteristic (ROC) classifier. Firstly, a total of 20 images of carcasses with diluted contaminants were acquired by hyperspectral imaging system, and 10 characteristic bands were extracted from the 1 232 bands by SPA. Then the MLR method was used to construct a regression model between the discriminant function and the characteristic spectral bands. Finally, the optimal classification threshold with high true positive rate (TPR) and low false positive rate (FPR) was determined by ROC analysis. Thus, the SPA-MLR-ROC classifier allowed the identification of the diluted contaminants. The results showed that the TPR of the SPA-MLR-ROC classifier was 98.08% and the FPR was only 0.39%. The detection accuracy was higher than that of the band ratio algorithm and the dual-band algorithm. Hence, the SPA-MLR-ROC classifier exhibited good performance for the detection of diluted contaminants on the surface of chicken carcass. However, because of the limited number of samples, further study using more samples is needed to verify the stability and feasibility of this method.

Based on the inhibition of citreoviridin (CIT) on luminol-hydrogen peroxide-nanometer copper oxide chemiluminescence system, a new method was proposed for the identification of sudden drinking water pollution. The detection system was optimized by one-factor-at-a-time and orthogonal array design methods. Results showed that under the optimized experimental conditions, the linear range for CIT determination was 0.005–3 mg/L. The limit of detection (LOD) of CIT was 8.2 × 10-5 mg/L. The precision expressed as relative standard deviation (RSD) was 2.3% for 11 replicate determinations of 0.005 mg/L CIT, and the recoveries of spiked samples were 78%–91%. This online determination method showed the advantages of convenience and strong practicability and could have a great potential application in rapid detection of sudden citreovirid pollution in drinking water.

Objective: To compare the swabbing and rinsing methods used for sampling chilled chicken by evaluating their effects on microbial DNA extraction and subsequent high-throughput sequencing. Methods: Four chilled chickens were divided into equal halves and sampled by superficial swabbing and rinsing methods for each half, respectively. Microbial genomic DNA was extracted from the collected samples and the V3-V4 region of the bacterial 16S rRNA gene was amplified by PCR. The PCR products were then subjected to high-throughput sequencing on an Illumina HiSeq sequencing platform. The obtained sequences were processed and analyzed using QIIME and other softwares. Results: There was no difference in bacterial genomic DNA extraction or bacterial community richness, diversity and structures between the samples collected by the two methods (P > 0.05). High-throughput sequencing showed that the bacterial community in chilled chicken samples consisted mainly of 7 phyla and 10 genera. Proteobacteria was the dominant phylum, accounting for more than 70% of the bacterial community; Shewanella, Pseudomonas, Acinetobacter, Psychrobacter, and Brochothrix were the dominant genera, each representing 10%?20% of the bacterial community. Conclusions: The two sampling methods exhibit no obvious difference in bacterial DNA extraction from chilled chicken or high-throughput sequencing. However, compared with swabbing, rinsing has the advantages of easy operation and non-secondary contamination, so it is more practical in microbiological analysis of chilled chicken. The experiment also provides useful data for the study of bacteria on chilled chicken.

A method has been developed to determine 55 plastic additives including antioxidants, plasticizers, ultraviolet light absorbers in yogurt by solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS). Samples were extracted with acetonitrile and the extract was then cleaned up on an HLB SPE column. The UPLC system equipped with a ACQUITY UPLC BEH C18 analytical column (2.1 mm × 50 mm, 1.7 μm) was operated utilizing methanol-0.1% formic acid as the mobile phase in gradient elution mode. Electrospray ionization in positive ion mode (ESI+) with multiple reaction monitoring (MRM) was used, and the analytes were quantified by the external standard method. The calibration curves displayed good linearity in a wide concentration range with a correlation coefficient of over 0.97. The average recoveries from spiked yogurt at three concentrations ranged from 62.4% to 93.5% with relative standard deviations (RSD) varying from 2.4% to 13.4%. The limits of detection (LOD) were 0.2–40 μg/kg. Twenty-three plastic additives at concentrations from 7.0 to 39 μg/kg were detected in 20 samples by the proposed method. This method can simultaneously identify and quantify a wide variety of plastic additive compounds with distinctive physicochemical properties in yogurt with high sensitivity.

In this study, we identified the main sources of uncertainty by mathematical modeling and calculated the main uncertainty components and combined and expanded uncertainties for the determination of inorganic mercury, methyl mercury and ethyl mercury in Boletus by high performance liquid chromatography combined with atomic fluorescence spectrometry (HPLC-AFS). The results showed that the major factors of uncertainty were concentration, instrumental measurement, sample heterogeneity, and recovery. Moreover, the curve fitting was the major factor causing the uncertainty for concentration. This study may provide a guideline for uncertainty evaluation for determining inorganic mercury, methyl mercury and ethyl mercury in edible fungus by HPLC-AFS.

DNA traceability technology is based on DNA sequence differences between individuals for individual identification and the tracing of meat back to an individual animal. Establishing a DNA-based traceability system is important for the safety and quality of meat products. The genetic diversity of 33 new single nucleotide polymorphism (SNP) markers was detected in a test group (233 individuals, 10 varieties) and 6 SNP markers, which are useful for pork product traceability, were obtained by heterozygosity calculation. A total of 18 SNP markers (6 new SNP markers in combination with 12 SNP markers) could effectively distinguish between 100 individuals collected from a local slaughter house in traceability simulation experiments. The corresponding individuals for tissue samples from 10 random individuals were found by genotype. This study has shown that SNP markers could be used for individual identification and pork traceability.

A nondestructive examination was conducted to identify unsound kernels by using hyperspectral imaging technology. Based on 932 wheat samples including 486 normal samples, 170 damaged samples, 149 worm-eaten samples and 127 black germ kernel samples, a hyperspectral image acquisition system was used for collecting hyperspectral information, and then a convolutional neural network (CNN) was established based on 30 wavebands selected from 116 wavebands for each sample. The CNN model comprised two convolution layers. The first layer consisted of 32 convolution kernels (3 × 3) and the second layer consisted of 64 convolution kernels (5 × 5). The pooling layer was developed with the maximum pool. The activation function was developed with rectified linear units (ReLu). To avoid overfitting, a dropout layer was linked to the fully connected layer, and the parameter was set as 0.5. When other parameters remained default, recognition rates for the calibration and test sets were 100.00% and 99.98% respectively. Finally, a support vector machine (SVM) model was built and compared with the CNN model. The SVM model developed with 90 wavebands selected from 116 wavebands showed a recognition rate of 94.73% for the test set. The recognition rate of the CNN model was better than that of the SVM model. Thus, this research showed that the CNN model allowed for accurate, rapid and nondestructive detection of unsound wheat kernels.

A quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction procedure was presented andoptimized for the determination of sterigmatocystin in eggs by high performance liquid chromatography-mass spectrometry (HPLC-MS). The analyte was extracted from samples with aqueous acetonitrile solution, followed by salting out using anhydrous NaSO4, NaCl and CH3COONa,and then purification and concentration with C18 sorbent and anhydrous Na2SO4 before analysis. Optimization of experimental conditions for maximum extraction efficiency was carried out using Plackett-Burman design, one-factor-at-a-time method and response surface methodology. The matrix-matched external standard calibration was employed for quantification. Moreover, all positive sampleswere confirmed by immunoaffinity column chromatography. The results of validation showed that good linearity with a correlation coefficient (R2) > 0.999 6 was achieved within the range from 0.125 to 1 000 ng/mL. The limit of detection (LOD) and the limit of quantification (LOQ) for sterigmatocystin in eggs were 0.1 and 0.5 μg/kg, respectively. Satisfactory recovery (86.8%–90.4%) and inter-day reproducibility (RSD, 1.5%–6.2%) were obtained with blank egg matrices at three spiked levels. Finally, the established method was applied to analyze 45 real samples, 10 of which were positive at concentrations of 0.5 to 3 608 μg/kg.

An acetylcholinesterase (AChE) biosensor was prepared by cross-linking AChE and bovine serum albumin
(BSA) onto nitrogen doped carbon sphere-gold (N-Cs-Au) nanoparticles composite modified glassy carbon electrode
(GCE) and used for detecting carbofuran in spinach. The results showed that N-Cs-Au had a good electrical conductivity
and catalytic activity, effectively promoting electron transfer and consequently improving the sensitivity of AChE/N-Cs-
Au/GCE. It was found that there was a good linear relationship between the negative common logarithm of carbofuran
concentration (X) in the range from 2.3 × 10-10 to 2.3 × 10-5 g/L and the percentage inhibition of the peak current by
carbofuran (Y) as indicated by the equation: Y/% = −8.246 7X + 93.867 6 (R2 = 0.992 9). As calculated by 10% inhibition,
the limit of detection (LOD) for carbofuran was 6.763 9 × 10-11 g/L. The sensor showed recoveries of 91.417 7%–95.859 7%
for carbofuran in spiked spinach and high precision, which could meet the analytical requirements. Moreover, the sensor
was free from the interference of common heavy metals such as Pb, Cu, Cd and Mn and could provide a new method for
detecting carbofuran in foods.

A headspace-gas chromatography-mass spectrometry (SHS-GC-MS) method was presented for simultaneous determination of 14?toxic volatile organic?solvent residues?(dichloromethane, trichloromethane, 1,2-dichloroethane, benzene, carbontetrachloride, trichloroethylene, methylbenzene, tetrachloroethylene, chlorobenzene, ethylbenzene, m-xylene, p-xylene, o-xylene, and isopropylbenzene) in flavors and fragrances. The headspace conditions including equilibrium temperature and time and the instrumental conditions were optimized. Samples were subjected to headspace extraction at 80 ℃ for 30 min and the extract was then separated on an HP-1 capillary column. and detected by GC-MS in the selected ion monitoring (SIM) mode. The results showed that in the range of 0.5–50 μg/L, all of the calibration curves displayed good linearity with correlation coefficients of higher than 0.998. The average?recoveries of spiked samples were 71.7%–101.0% with?relative standard deviation (RSD) between 1.71% and 9.29%. The limits of detection (LODs) were 1.0–10.0 ng/g.