The effect of adding different amounts (1, 5, 10 and 20 mmol/L) of L-Lysine (L-Lys) on the heated-induced aggregation behavior of myosin from bighead carp was studied. Changes in pH, turbidity, rheological properties and gel strength were measured under three different heat treatments: keeping at 25 ℃ for 30 min (control), heating at 40 ℃ for 60 min, and two-stage heating at 40 ℃ for 60 min and then 90 ℃ for 30 min. The results showed that the pH value of myosin solutions increased with increasing concentration of L-Lys. The turbidity of the unheated myosin solution markedly decreased when it was blended with 20 mmol/L L-Lys. Additionally, the turbidity of samples with 1–20 mmol/L L-Lys reduced after heat treatments, especially after two-stage heating. Furthermore, the samples with L-Lys tended to be a viscous fluid with a weaker gel-forming ability as well as lower gel strength. In summary, as a commonly used solvent additive and essential amino acid, L-Lys can inhibit the heated-induced aggregation behavior of myosin via electrostatic interaction and by changing the pH value of myosin solution, and further study is needed for the exploitation and utilization of L-Lys.

Soy protein isolate (SPI)-dextran conjugates (CON) were prepared through Maillard reaction in solution under macromolecular crowding environment, then fractionated by their solubility at pH 4.5 (MC45) and pH 6.5 (MC65), and characterized. SDS-PAGE and molecular weight distribution of the conjugates showed typical patterns of conjugate formation and different characteristics between MC45 and MC65. The effects of pH, heating temperature and the addition of NaCl on the properties of emulsions stabilized with SPI-dextran conjugates were examined using a light-scatter particle size analyzer and a Zeta-potential analyzer. Results showed that in an acidic environment the average droplet size (d43) of the emulsion with MC45 was 10 μm, lower than that of the emulsion with MC65, and was little affected by ion concentration and temperature. Compared with native protein, SPI-dextran mixture and MC45, MC65 had better curcumin loading capacity with respect to loading amount (30.21 μg/mg) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity (18.33% DPPH scavenging) and resulted in larger particle size.

The present work aimed to improve the bioavailability of zein. We employed microbial transglutaminase as a biocatalyst, and chitosan with a molecular mass of 1 500 Da as an acyl acceptor to modify zein by glycosylation reaction. The functional properties of glycosylated zein were studied in comparison with its intact and cross-linked counterparts. The results of Fourier transform infrared (FT-IR) spectroscopy and free amino group content indicated that chitosan was covalently conjugated to zein under the catalysis of transglutaminase. The surface hydrophobicity of glycosylated zein was decreased significantly compared with that of the original and cross-linked ones, suggesting a significant improvement in the water solubility of zein. Meanwhile, antioxidant activities, including 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion and hydroxyl radical scavenging activities, reducing power and Fe2+-chelating capacity of glycosylated zein were increased significantly, and its EC50 value for DPPH radical scavenging activity was 0.945 mg/mL. Water-binding capacity, oil-binding capacity, emulsifying properties and the absolute value of Zeta potential of glycosylated zein were decreased significantly. These results can provide a basis for the application of glycosylated zein in the food industry.

Proteins isolated from the adductor muscle of of Chlamys farreri and common carp muscle (Cyprinus carpio) were glycosylated to improve their properties and the underlying mechanism was elucidated. A comparison of muscle proteins between marine invertebrates and vertebrates was carried out. The protein isolates were prepared in alkaline solution and then subjected to direct and indirect glycosylation. Direct glycosylation took place under drying conditions, while in indirect glycosylation the protein isolates were pretreated with?chymotrypsin before being reacted with glucose. Both glycosylation reactions were performed under identical conditions: protein-to-sugar ratio of 1:5 (m/m), 60 ℃, 65% relative humidity and 6 h. The glycosylation efficiency was evaluated by lysine reduction, fructosamine concentration, absorbance at a 420 nm (A420 nm) and SDS-PAGE analysis. Moreover, emulsifying properties and thermal stability of glycosylated products were determined. For both protein isolates glycosylation occurred after 6 h reaction, leading to a 59.89% and 30.94% reduction in lysine, fructosamine concentration of 3.04 and 2.99 mmol/L and A420 nm values of 0.000 and 0.084, respectively. Additionally, the electrophoretic bands of myosin heavy chain and actin were shifted upwards after glycosylation. The emulsifying activity index of the glycosylated proteins was 14.08 and 16.44 m2/g, respectively. Their thermal stability was improved, which decreased by 14% and 28% compared to 26% and 50% for the control counterparts, respectively. Chymotrypsin pretreatment could apparently increase the glycosylation efficiency of the protein isolate from scallop muscle. After glycosylation, the untreated and treated protein isolates showed a 30.94% and 67.64% reduction in lysine, a fructosamine concentration of 2.99 and 5.72 mmol/L, an upward shift of all protein bands, a 33.11% and 37.38% increase in emulsifying activity index and a 28% and 3% decrease in thermal stability, respectively. These results demonstrated that protein isolates from fish and scallop muscles had similar glycosylation characteristics. Chymotrypsin pretreatment evidently increased the glycosylation.

The relationship between volatile compounds produced during thermal degradation of carotenoids in sweet corn juice and its flavor was studied. By using C30-high-performance liquid chromatography with diode array detection-atmospheric pressure chemical ionization-mass spectrometry (C30-HPLC-DAD-APCI-MS) and solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS), the main carotenoids were separated and identified in fresh sweet corn juice. The volatile compounds generated in the heat-treated corn juice were analyzed. Then the correlation between the thermal degradation of carotenoids and the volatiles was examined. Results showed that 12 carotenoids were identified in fresh sweet corn juice. With increasing the heat temperature, the contents of all-trans carotenoids were reduced gradually, and the content of cis-carotenoids was firstly increased and then decreased. A total of 35 volatile compounds were determined in the fresh and heat-treated sweet corn juices. The contents of dimethyl sulfide, 1-octene-3-ol, methyl heptanone, β-ionone, and P-umbrella were increased during heating. The correlation analysis showed a significant and negative relationship between the aroma-active compounds β-ionone, methyl heptanone, limonene, benzaldehyde, 2-octanone, P-umbrella, toluene and 1,2,3-trimethylbenzene and thermal degradation of carotenoids. Among these aroma compounds, the contribution rates of lutein and β-carotene were the highest. Therefore, the major volatile compounds produced during the thermal degradation of carotenoids may play a non-negligible role in the flavor of sweet corn juice.

The effect of heat treatment on the nutritional value of fresh raw milk and reconstituted milk were studied by in vitro simulated digestion method. The treated samples were detected by SDS-polyacrylamide gel electrophoresis (SDS-PAGE), size exclusion high performance liquid chromatography, scanning electron microscopy and mass spectrometry. The results showed that some milk proteins were broken down during simulated gastric digestion, and casein showed the highest degree of breakdown. The level of digestion of casein in fresh milk by the gastric juice was higher than that of other heat-treated samples. After digestion with the intestinal juice, milk proteins were completely broken down into free amino acids and small peptides, and the digestibility of fresh milk was higher than that of other heat-treated samples. Milk proteins were mainly digested into peptides with molecular weight of less than 1 500 Da, which can be easily absorbed by the body. It was observed by scanning electron microscopy (SEM) that heat treatment induced denaturation and aggregation of milk proteins and that the particle size of reconstituted milk was larger than that of other milk samples with increasing heating temperature. Analysis by mass spectrometry (MS) and high performance liquid chromatography (HPLC) revealed that greater degree of heat treatment resulted in higher reaction degree in Maillard reaction.

Solubility, surface hydrophobicity (H0), Zeta potential, particle size and molecular structure of 11S glycinin at different ionic strengths were determined. The effect of ionic strength on H0 and structure of 11S glycinin was explored. Results showed that the solubility and absolute value of Zeta potential were decreased whereas H0 and average particle size were increased with increasing ionic strength from 0 to 0.9. Moreover, the content of α-helix structure was decreased and the content of β-sheet structure was increased. The tyrosine and tryptophan residues of the protein was transformed from “embedding” to “exposure” state as the ionic strength was increased, leading to an increase of H0. The disulfide bond configuration of 11S glycinin at different ionic strengths was changed, possibly affecting its H0.

mok E gene belongs to the Monacolin K biosynthesis gene cluster, whose expression level is positively correlated with Monacolin K production. In this research, mok E gene was overexpressed in Monascus M1 and its expression level was measured by reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR). The Monacolin K production in transformants was measured by high performance liquid chromatography (HPLC). The morphological features of mycelia and spore of the wild-type strain and the transformants were observed by scanning electron microscope (SEM). The results showed that 240 transformants were obtained by hygromycin resistance selection. Nine of these transformants were selected for the measurement of mok E expression by RT-qPCR. The expression levels of mok E gene were enhanced in three transformants, T2, T8 and T9. The production rates of Monacolin K lactone in transformants T2, T8 and T9 were 2 159.7, 4 177.6, and 3 365.7 μg/g, respectively, which were increased by 49.2%, 188.5% and 132.5%, respectively, compared with that in the wild-type strain (1 447.8 μg/g). The results of SEM revealed that mok E overexpression contributed to the morphological changes of mycelia and spore.

The optimization of medium components for improved succinic acid production by Actinobacillus succinogenes GXAS137 at reduced cost was performed using one-factor-at-a-time method and response surface methodology. The independent variables considered were electron acceptors, crude glycerol concentration and nitrogen sources. The results showed that dimethyl sulfoxide (DMSO) was the optimum electron acceptor and corn steep liquor (CSL) could be used as an alternative nitrogen source to replace yeast extract. The optimum culture medium that provided maximum succinic acid yield of 37.02 g/L, which was increased by 119% compared to that (16.88 g/L) before optimization, was composed of crude glycerol 55.43 g/L, DMSO 10.35 g/L and CSL 17.69 g/L. Under this optimized condition, the conversion rate of glycerol to succinic acid was 66.79% and succinic acid productivity was 0.51 g/(L·h). This study can provide a basis for the microbial production of succinic acid from crude glycerol.

The experimental conditions to obtain a genetically stable haploid strain from the Saccharomyces cerevisiae diploid strain W5 were optimized in this study. Seven haploid strains were isolated and identified by random spore analysis and MAT-PCR. Then, the stability of the haploid strains was evaluated by continuous passage culture. Ultimately, the fermentation performance of two selected haploid strains was analyzed. The results showed that the highest sporulation rate of the strain W5 of (35.57 ± 0.82)% was acquired when it was cultured on a modified SPM medium at 30 ℃ for 8 days. Spore release rate was (47.06 ± 0.23)% after 2 h treatment of the suspension with 3% snailase. S. cerevisiae H14 (MAT-a) was the most genetically stable among seven haploid strains. Strain H14 gave the highest ethanol production of (40.46 ± 1.06) g/L when cultured at 30 ℃ with glucose as a substrate for 30 h with agitation at 150 r/min, which was 21.67% lower than that of W5 at 24 h, whereas the yields of acetic acid and acetoin were increased by 12.7% and 57.14%, respectively. This research can provide useful information for researchers to prepare haploid S. cerevisiae and also enrich the fundamental theory of yeast genetics.

To evaluate the impact of adding exogenous protease on sufu ripening, the pH, moisture, total acid content, amino nitrogen content, hardness and sensory quality were determined during the post-fermentation of sufu with no enzyme, papain or rennet added. The results showed that addition of exogenous proteases increased the pH of sufu compared with the control group after 5 days of ripening but it had no significant effect on moisture or total acid content. Addition of 4% papain, 2% or 4% rennet remarkably promoted the production of amino nitrogen. Hardness was decreased by adding 4% papain or 4% rennet. The results of sensory evaluation showed that exogenous proteases improved the taste, internal color, aroma and umami of sufu, but bitterness was formed as a result of the hydrolysis of soybean protein with papain.

HD-Zip transcription factors play an important role in plant growth and development, and studies at the protein level contribute to further elucidating their functions. Herein, the MdHB1 transcription factor gene from apple (Malus domestica) was cloned into the expression vectors pGEX-6p-1 and pET-28a(+), which were then transferred into BL21 (DE3) competent cells by heat shock for expression using isopropyl-β-D-thiogalactoside (IPTG) as an inducer. MdHB1-GST and MdHB1-His6 fusion proteins were obtained. SDS-PAGE analysis showed that at 18, 28 and 37 ℃, MdHB1-GST fusion protein existed mainly in the form of inclusion body and at lower temperatures (18 and 28 ℃) the ratio of soluble fusion proteins to the total proteins was increased. At 28 ℃, the content of fusion protein induced by 50 mg/L IPTG reached its maximum value after about 8 h, irrespective of different IPTG concentrations (10, 50 and 100 mg/L). Polyclonal antibody was prepared by immunizing adult rabbits with the MdHB1-His6 fusion protein purified by Ni-NTA column chromatography. Enzyme-linked immunosorbent assay (ELISA) showed that the polyclonal antibody had a high titer. Western blot assays showed that the polyclonal antibody could specifically recognize the MdHB1 protein in Escherichia coli and young apple leaves. Taken together, the polyclonal antibody could be used to explore the function of MdHB1 in plants.

Arginase is an alkaline hydrolases that catalyzes the production of urea and L-ornithine from arginine. An arginase gene encoding 297 amino acids was cloned from Bacillus tequilensis PanD37. By recombinant DNA technique, a genetically engineered strain of Escherichia coli was constructed for heterologous expression of the gene. Enzymatic assays indicated that the recombinant enzyme exhibited maximum activity at pH 10.0 and 45 ℃. Its activity was stable in the temperature range of 50–60 ℃ and in the pH range of 8.0–10.0. The enzymatic activity could be significantly activated by Mn2+, Ni2+, and Co2+. The activity of crude enzyme was 1 109.8 U/mL.

Solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) was used to analyze the volatile compounds in 20 Kazak cheese samples collected from different regions of Xinjiang, China. A total of 52 volatile flavor compounds were detected in the cheese samples, and the major characteristic flavor compounds included acids (acetic acid, butyric acid, heptanoic acid, and octylic acid), alcohols (ethanol, phenyl ethanol and 3-methylbutanol), esters (ethyl acetate, ethyl hexanoate and ethyl octanoate), ketones (2-nonanone and 2-heptanone), aldehydes (hexanal, heptanal and nonanal), and terpene compounds. Principal component analysis showed that the flavor compounds of cheese from different areas were different, and discrimination between cheeses from Ili and Hami was excellent with clear distinctions. Cheeses from Altay and Tacheng showed a high degree of similarity in their volatile flavor composition and belonged to the same group. The main flavor compounds of Ili cheese were acetic acid, ethyl acetate, 3-methyl-1-butanol acetate, ethyl caproate, 2-methyl ethyl butyrate, 3-hydroxy-2-butanone, 2-butyl alcohol, 2-hydroxy ethyl propionate and 2-methyl propyl alcohol, and were different from those from other regions. The flavor of Barkol sample (H1) from Hami was better than that of other samples from the same region, with the dominant compounds being aldehyde (hexanal, 2-heptanal, benzaldehyde and nonanal), esters (ethyl propionate, butyl acetate, butyl propionate, 2-butyl acrylate, butyl butyrate) and 2-nonanone.

The volatile flavor compounds of fast-ripened Cheddar cheese slurry model fermented with Tibetan kefir and Cheddar cheese model fermented with commercial starter were extracted by solid phase micro-extraction (SPME) and identified by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O). Results showed that the main volatile flavor components of Cheddar cheese model fermented with Tibetan kefir were alcohols and esters during its ripening. The number and amount of volatile flavor compounds in Cheddar cheese model fermented with Tibetan kefir were both higher than in Cheddar cheese model fermented with commercial starter. The volatile compounds which most significantly differed between two cheeses were esters. Sensory evaluation and flavor analysis showed that the number and amount of esters and alcohols in Cheddar cheese model fermented with Tibetan kefir were greater and it had a stronger flavor with fruity and wine aromas.

In this study, a bottom-up method was established for the fast screening of eicosapentaenoic acid (EPA), docosapentenoic acid (DPA), and docosahexaenoic acid (DHA) acyl chain containing phospholipids. The oil extract from aquatic byproducts was injected using a syringe pump, and monitored under precursor ion scan (PreIS) mode with ?100 V declustering potential (DP) and ?40 V collision energy (CE) in the range of 350–1 150 Da. The product ions of m/z 301, 329 and 327 were used as the representative ions for EPA, DPA and DHA chains, respectively. The peaks of EPA, DPA and DHA were identified and quantified. The results showed that the aquatic byproducts contained many different types of EPA, DPA and DHA containing phospholipids. A total of 50 phospholipids of interest were identified, whose sn-1 positions were C16:0, C18:1 or C18:0 chains, including phosphatidylserine 20:5/22:6 and phosphatidylinositol 22:6/22:6, which were extremely unsaturated. Aquatic byproducts rich in EPA, DPA and DHA containing phospholipids therefore show great potential in the development of functional foods. The method was validated and found to be stable and precise as indicated by the relative standard deviations (RSDs) lower than 7.3%. In conclusion, this method is advantageous in fast screening of ω-3 fatty acyl chain containing phospholipids. Theoretically, this method is applicable to other biological samples as well, and can provide strong support for searching for new resources of ω-3 fatty acyl chain containing phospholipids.

The slaughter performance of Sunit sheep and Small-Tailed Han sheep (5-month-old, 10 animals for each breed) was investigated. The quality, fatty acid composition and volatile compounds of Longissimus dorsi muscles from these lambs were comparatively evaluated. The results showed that the meat percentage and bone to meat ratio of Sunit lambs were significantly greater than those of Small-Tailed Han lambs (P < 0.05). In addition, in terms of meat color parameters (a* and b*) and tenderness Sunit lambs were better than Small-Tailed Han lambs (P < 0.05). There was, however, no significant difference in cooked meat percentage or pH between the two breeds. Fatty acid analysis showed that the contents of saturated?fatty?acids (SFA) and polyunsaturated fatty acids (PUFA) in Sunit lambs were higher than in Small-Tailed Han lamb. The contents of palmitic?acid (C16:0) and stearic?acid (C18:0) in Sunit lambs were significantly higher than in Small-Tailed Han lambs (P < 0.05), but no significant differences in the dominant unsaturated fatty acids (C18:1, C18:2n6c and C20:4n6) were present between both breeds. The main volatile compounds identified in lamb meat were carbonyl and alcohol compounds and the contents and composition of these compounds were largely affected by breeds with aldehydes and acetones being more abundant and alcohols being less abundant in Sunit lambs than in Small-Tailed Han lambs. Hexanal, octanal nonanal, 1-octen-3-ol and 2, 3-octanedione may be mainly responsible for the formation of meat flavor.

Vitamin C is a small water-soluble molecule in vivo which can be directly involved in the redox reaction, with a variety of physiological activities. Herein, an ultra-bright triple-doped zinc gallogermanate nanostructure with favorable monodispersity and optically stable near infrared (NIR) luminescence whose surface was modified with cobalt oxyhydroxide (CoOOH) was synthesized by a surfactant-aided hydrothermal method in combination with short time calcination, and a nanoprobe for the detection of vitamin C was built based on the specific reaction of CoOOH and vitamin C. The nanoprobe used the ZGGO:Cr3+, Yb3+, Er3+ persistent luminescence nanoparticles (PLNPs) as optical signal units and CoOOH as quencher, allowing the detection of vitamin C with high selectivity and sensitivity based on the inner filter effect (IFE). The results showed that CoOOH could effectively quench the luminescence of PLNPs. Vitamin C could restore the luminescence of PLNPs by reducing CoOOH, which displayed a good linear correlation with the content of vitamin C (R2 = 0.993 15) and a detection limit (LOD) of 1.18 mg/kg. When applied to real samples of lemon, strawberry and kiwi fruit, this method gave results consistent with those from HPLC. In addition, the synthesized ZGGO:Cr3+, Yb3+, Er3+ PLNPs had a long afterglow performance in the near infrared (NIR) region, and therefore could be applied to real-time monitoring and imaging of vitamin C in living cells and organisms without in situ excitation.

A total of 41 fresh apple samples from 21 varieties were collected from 7 major producing regions for this study. The quality indicators of cloudy juices from these apples were measured, including juice yield, turbidity, color, browning degree, light transmittance, soluble solids, titratable acid, total phenols, sugar, organic acid, VC, minerals, and antioxidant activity. The obtained data were analyzed by general descriptive and stepwise linear discriminant analysis. The results showed that the quality of cloudy apple juices varied with cultivar and geographical origin. Overall, a* value, original turbidity, browning degree, titratable acid, glucose, sucrose and malic acid varied significantly among cultivars (by 94.07%, 70.41%, 42.86%, 35.26%, 42.02%, 42.40%, and 37.69%, respectively). Due to their significant differences in color quality indicators such as browning, total phenols, antioxidant activity and nutrients such as sugar and acid, the apple juices from different cultivars were distributed dispersively. The browning degree, total phenols content, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging capacity of the Starkrimson cultivar were generally higher, and the color quality was best. Most Fuji samples were rich in fructose, glucose, sucrose, malic acid and had good nutritional quality. In addition, the samples from different producing areas showed striking differences in turbidity, titratable acid, soluble solids content. The juice yield, original turbidity and titratable acid content of juice samples from Hebei province were generally lowerer and they were not suitable for juice processing. Similarly significant differences were observed among cloudy apple juices from different cultivars in Shandong province and among Fuji cloudy apple juices from different producing areas, and the discrimination accuracy for the cultivars and producing areas were 77.8% and 72.7%, respectively. The above results showed that there were significant differences among apple juices from different cultivars and different producing areas. Analysis of the differences in quality parameters can provide a basis for apple breeding and restructuring of planting industry. Identification and prediction of cultivars and geographical origins based on a discriminant model can provide guidance for apple juice enterprises to choose suitable cultivars for juice processing.

The volatile compounds in spiced donkey meat were extracted by solvent-assisted flavor evaporation (SAFE) and identified by odor activity value (OAV) calculation and gas chromatography-olfactometry-mass spectrometry (GC-O-MS). A total of 48 volatile compounds were identified in spiced donkey meat and 13 and 21 flavor-active compounds were identified by OAV calculation and GC-O-MS, respectively. The combination of two methods suggested that the key flavor-active compounds (OAV > 200 and aroma intensity = 3) included cineole, eugenol, anethole, 1-nonanal, 2-methyl pyrazine, 2,6-dimethyl pyrazine, 2-acetyl pyrrole, and maltol.

This study aimed to detect and compare the free amino acid composition in human and bovine milk at different lactation stages using isobaric tags for relative and absolute quantification (iTRAQ) combined with high performance liquid chromatography-mass spectrometry (HPLC-MS/MS) (HPLC-MS/MS-iTRAQ). The results indicated that human milk contained more types and higher contents of free amino acids compared with bovine milk. In addition, the total content of free amino acids showed a declining trend during the whole lactation period. The total contents of free amino acids were 0.32, 0.16, 0.63 and 0.37 g/L in bovine colostrum, bovine milk, human colostrum and human milk, respectively. Among 42 free amino acids detected in this study, 35 were found in human milk and 31 in bovine milk. Moreover, the contents of 25 free amino acids in human milk were higher than in bovine milk. In particular, a significant increase in histidine, phenylalanine and threonine were observed (P < 0.05). The content of free glutamic acid was the highest in bovine milk, human colostrum and human milk, while taurine was the most abundant free amino acid in bovine colostrum. Understanding the differences in free amino acid composition between human milk and bovine milk can lay a theoretical foundation for detailed studies on amino acid functions and metabolomics in human milk. In addition, this study can provide a basis for producing infant milk powder and functional dairy products.

The blanching of Volvaria volvacea during the processing of a new read-to-eat spicy product was optimized based on surface lightness. The volatile compounds of fresh and processed V. volvacea were analyzed by headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). A comparative evaluation of this product and other similar products was carried out using an electronic tongue. The results showed that the optimal conditions for blanching V. volvacea were found to be blanching in a mixed solution containing 0.2 g of citric acid and 0.06 g ascorbic acid per 100 mL sample for 1 min. A total of 27 volatile flavor components were detected in fresh V. volvacea, and 24 volatile flavor components in the processed product. The most significant differences in the composition and contents of aldehydes were found between fresh and processed mushroom. The relative contents of benzaldehyde and phenylacetaldehyde in the processed product were significantly lower and the relative content of pelargonaldehyde was greatly higher than in fresh V. volvacea. The results of electronic tongue indicated that there were significant differences among this product, canned V. volvacea and V. volvacea appetizer in terms of their salty, sour and umami taste. This product was characterized by moderate saltiness and strong umami taste.

This study aimed to analyze the physicochemical properties and polyphenolic composition and to evaluate the antioxidant and anti-inflammatory activities of stingless bee honey (SBH) from Hainan, China. The polyphenolic compounds were analyzed by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS). The contents of total phenolics and total flavonoids in SBH extract were determined by the Folin-Ciocalteu method and AlNO3 colorimetry, respectively. The antioxidant activity of SBH was assayed in vitro by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate radical) (ABTS+·) scavenging and reducing power methods. Its anti-inflammatory effect was investigated using lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Our results showed that SBH possessed the physicochemical properties: moisture content (26.3 ± 0.1)%, pH 3.7 ± 0.2, protein content (628.2 ± 9.0) mg/kg, amylase activity (19.6 ± 0.2) mL/(g·h), fructose content (21.0 ± 3.7)%, glucose content (24.9 ± 2.2)%, sucrose content (0.8 ± 0.1)%. The contents of total phenolics and total flavonoids in the extract were (96.6 ± 0.4) μg CAE/g and (16.1 ± 0.3) μg QE/g, respectively. The IC50 values of the extract for scavenging of DPPH and ABTS radicals were (435.1 ± 0.4) and (423.0 ± 0.3) μg/mL, respectively, and its ferric reducing power was (0.6 ± 0.02) μmol Trolox/g. SBH exhibited potent concentration-dependent anti-inflammatory effects by inhibiting nitric oxide (NO) release from LPS-stimulated RAW 264.7 cells, markedly decreasing the mRNA expression of iNOS, IL-1β, IL-6 and MCP-1, and significantly increasing the mRNA expression of HO-1. These results suggest that SBH was rich in nutrients, phenolic acids and flavonoids, and had potent antioxidant and anti-inflammatory properties, making it very promising.

A USB2000+ micro spectrometer was used to acquire the transmittance spectra of Red Globe table grapes in the range of 400–1 000 nm. Moreover, the sugar content and acidity value were measured chemically. The original spectra were pretreated by SavitZky-Golay smoothing (SG) and then the singularity was eliminated by Monte-Carlo cross validation method (MCCV) followed by dimension reduction by competitive adaptive reweighted sampling for development of a random forest (RF) prediction model. The correlation coefficient and root mean square error of the sugar prediction model were 0.955 8 and 0.315 8 for the calibration set, and 0.956 8 and 0.318 5 for the validation set, respectively. The correlation coefficient and root mean square error of the acidity prediction model were 0.945 6 and 0.300 1 for the calibration set, and 0.940 5 and 0.311 2 for the validation set, respectively. The results showed that this method could be suitable for rapid, nondestructive and accurate detection of sugar content and acidity in Red Globe table grapes.

A method for the determination of 5 selenium species (SeCys2, SeMC, Se(IV), SeMet, and Se(VI)) in selenium-enriched tea was established using high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). A Hamilton PRP-X100 column was used to separate the five compounds using citric acid as the mobile phase. Quantification was performed by the external standard method. The five selenium compounds were ultrasonically extracted using 1 mL of protease K (10 mg/mL) for 60 minutes, and then separated with gradient?elution in 15 min. The correlation coefficients of the standard curves were larger than 0.999 8, and the limits of detection (LODs) were in the range of 0.13–1.09 μg/L. The spiked recoveries ranged from 91.8% to 109.4%. The method allowed simultaneous determination of selenium compounds in selenium-enriched?tea with simple and convenient operation, efficient separation and low detection limit.

An analytical method using quick, easy, cheap, effective, rugged and safe (QuEChERS) pretreatment combined with high performance liquid chromatography-quadrupole-time of flight mass spectrometry (HPLC-Q-TOF-MS) was established for the quick screening of lignanoids in Schisandra chinensis. Sample pretreatment conditions were optimized. Chromatographic separation was accomplished on an Xbridge BEH C18 column with gradient elution. The mass spectrum was acquired by information dependent acquisition mass spectrometry (IDA-MS). The qualitative and quantitative analyses were based on the accurate masses of parent ions and isotopic patterns, and the accurate masses of fragment ions as well as a priori known retention times. The results showed that the limits of detection (LODs) for the three standards were within the range of 0.3–1.5 μg/L, and calibration curves offered satisfactory linearity (R2 ≥ 0.999 6) in a wide linear range. Lignanoids in S. chinensis samples could be quickly identified by searching in the high-resolution mass spectral library XIClists developed in this study.

This study aimed to understand the change of aroma components during flowery black tea processing. One bud with two or three leaves from tea populations in Huangsan Mountain were used to produce Congou black tea by the traditional process or flowery black tea through withering, rocking, rolling, fermentation and drying. The change of aroma components during the processing of the teas was analyzed by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). The results indicated that there were significant differences in geraniol, methyl salicylate and geranylacetone between flowery black tea and Congfu black tea. The contents of methyl salicylate, alpha-cadinol and, trans-2-hexenyl hexanoate were increased during rocking. During fermentation, the contents of benzaldehyde and geraniol were increased. The contents of 3,7-dimethyl-1,5,7-octatriene-3-ol, (E,E)-2,4-nonadienal, cis-3-hexenyl hexanoate were increased during drying. During the whole process, the contents of (E)-2-octenal, phenacetaldehyde, and benzyl alcohol were changed greatly. The contents of (E,E)-2,4-nonadienal, (E,E)-2,4-decadienal, hexanoic acid, (Z)-3-hexenyl ester , hexanoic acid, and (E)-2-hexenyl ester were also increased whereas the contents of geraniol, methyl salicylate, and alpha-cadinol were decreased.

α-Tocopherol/casein nanoparticles were prepared by self-assembly and their stability was assessed. The binding strength between α-tocopherol and casein was evaluated by fluorescence intensity. The composite nanoparticles were characterized and the retention rate of α-tocopherol was used as an indicator to evaluate its stability. The results indicated that the optimum conditions for preparing α-tocopherol/casein nanoparticles were as follows: 37 ℃, pH 6.8 and α-tocopherol/casein mass ratio of 1:300. The nanoparticles prepared using the optimized conditions showed an average diameter of (135.6 ± 13.7) nm, an encapsulation efficiency of (97.97 ± 7.38)% and a drug loading of (0.33 ± 0.03)%. Strong hydrogen bonds existed between α-tocopherol and casein as indicated by Fourier transform infrared spectroscopy analysis. The nanoparticles were uniform in size and regularly spherical in shape and had good dispersibility. Compared with α-tocopherol, the nanoparticles showed better stability to storage, high temperature, lyophilisation and oxidation. The α-tocopherol/casein nanoparticles could effectively improve the stability of α-tocopherol, thereby having a wide scope of application and showing promise in the food industry.

The purpose of this study was to investigate the Maillard reaction between snapper fish scale peptides (FSP) and xylose (Xyl) as a function of reaction time, mass ratio of Xyl to FSP, total concentration of Xyl and FSP, initial pH and temperature and to characterize the structure and properties of Maillard reaction products prepared from a mixture of Xyl and FSP (1.3:1, total concentration of 78 mg/mL, at initial pH 11.85) at 100 ℃ for 4.05 h. The changes in fluorescent intensity, Fourier transform infrared spectra, free amino group content and Tricine-SDS-PAGE with periodic acid Schiff staining suggested that covalent crosslinking between FSP and Xyl occurred, the structure of FSP was changed and new compounds were formed through Maillard reaction. 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, 2,2’-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt radical (ABTS+·) scavenging, hydroxyl radical scavenging and reducing power assays suggested that the antioxidant activity of FSP was significantly improved via Maillard reaction (P < 0.05). The Maillard reaction products inhibited polyphenol oxidase activity with IC50 value of 0.54 mg/mL. The underlying mechanism may be attributed to their Cu2+-chelating activity and the chelating sites may be related to antioxidant groups.

One-factor-at-a-time method and response surface methodology (RSM) were used in combination to optimize the extraction of arabinoxylans from hull-less barley bran with aqueous sodium hydroxide solution. The independent variables investigated were solid to solvent ratio, temperature, extraction time and sodium hydroxide concentration, while the response variable was the yield of arabinoxylans. Each independent variable was tested at three levels. The optimum conditions obtained were as follows: solid to solvent ratio, 1:25 (g/mL); extraction temperature, 55 ℃; extraction time, 3 h; and sodium hydroxide concentration, 15 g/L. Under the optimized conditions, the yield of arabinoxylans was 14.31%, which agreed well with the predicted value of 14.27%. Thus, the optimized process was stable and feasible. Analysis of purity and structural properties by high-performance gel permeation chromatography (HPGPC), UV absorption spectroscopy, IR spectroscopy, high-performance anion-exchange chromatography (HPAEC) showed that the arabinoxylans were homogeneous and contained a small amount of protein but no nucleic acid and they were mainly composed of four monosaccharide units: arabinose, galactose, glucose and xylose with a molar ratio of 11.61:1:3.62:18 ( molar ratio of arabinose to xylose = 0.645), which were linked via α and β-glycosidic bonds.

In this study, soluble gelatin-chitosan composite was prepared by electrostatic bonding and it was further used as a carrier to prepare eugenol nanocapsules by self-assembly method. The preparation conditions were optimized using one-factor-at-a-time and orthogonal array design methods. Chitosan concentration, gelatin concentration, crosslinking time, rotation speed and eugenol concentration were used as independent variables whose effects on particle size and encapsulation efficiency were evaluated. The nanocapsules prepared under optimized conditions were characterized. The results showed that the optimal preparation conditions were determined as 2 mg/mL, 2 mg/mL, 5 mg/mL, 800 r/min and 30 min for chitosan concentration, gelatin concentration, eugenol concentration, rotation speed, and crosslinking time, respectively. The average particle size of the obtained eugenol nanocapsules was 229.09 nm and the encapsulation efficiency was 50.69%. The eugenol nanocapsules were uniform in size and regularly spherical in shape as characterized by TEM. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) showed that eugenol and gelatin interacted via hydrogen bonds and hydrophobic forces. Eugenol could be controlled released from the nanocapsules. In summary, the preparation process was simple, green and mild and could expand the application scope of eugenol and improve its bioavailability. The nano-encapsulation system has potential application in food preservatives.

Corn straw nanocellulose (NCSC) was prepared by ultrasound-assisted sulfuric acid hydrolysis method. The effects of experimental conditions on the yield of NCSC were studied. The optimum conditions were obtained using response surface methodology as follows: H2SO4 concentration, 64%; ultrasonic power, 160 W; temperature, 48 ℃; and hydrolysis time, 78 min. Under these conditions, the yield of NCSC was 38.29%. The NCSC was white and delicate, and had good water swelling force. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) showed that the NCSC maintained the basic chemical structure of corn straw cellulose (CSC). Its crystallinity (70.53%) and thermal decomposition temperature were higher than those of CSC.

In this study, a rapid method using Fourier transform infrared and ultraviolet absorption spectroscopies coupled with data fusion was established for the identification of the geographical origin of Boletus tomentipes. The original spectra of 96 samples collected from different growing regions were preprocessed by multiplicative signal correction (MSC), standard normal variate (SNV) and second derivative (2D) to decrease the noise interference. The spectral information about the fingerprint characteristics was chosen for low-level data fusion, and the spectral information of variables important in projection greater than 1 was selected by partial least squares-discriminant analysis (PLS-DA) for mid-level data fusion. Then the single and fused spectral data were analyzed by PLS-DA and support vector machine (SVM). The prediction performance of PLS-DA and SVM was compared. The results showed that based on FTIR, UV, low-level data fusion and mid-level data fusion data matrixes, the prediction accuracies of PLS-DA were 56.25%, 56.25%, 62.50% and 81.25%, respectively, and the prediction accuracies of SVM were 90.63%, 65.63%, 87.50% and 96.88%, respectively, suggesting that mid-level data fusion was better than the other data sources and SVM was better than PLS-DA. In conclusion, SVM based on mid-level data fusion can be a rapid and effective method for the identification of the geographical origin of B. tomentipes that facilitates food quality monitoring.

An electrochemical sensor was constructed by immobilizing graphene as a new nanomaterial and chitosan on glassy carbon electrodes. The electrochemical properties of benzo(a)pyrene were investigated? and a rapid and sensitive method for the detection of benzo(a)pyrene in vegetable oils was established. A well-defined oxidation peak was observed at 1.0 V according to the cyclic voltammogram of benzo(a)pyrene at the nano electrochemical sensor and no reduction peak appeared, indicating that this is an irreversible redox process. The experimental conditions for electrochemical detection of benzo(a)pyrene in vegetable oils were optimized as follows: 5 μL of a mixed solution of chitosan-graphene (1:2, V/V) was used as modified solution; the concentration of LiClO4 as electrolyte was 0.2 mol/L; sulfuric acid concentration was 0.1 mol/L; and the enrichment time was 15 min. Under these optimal conditions, there was a good linear relationship between the redox peak current of benzo(a)pyrene and its concentration in the range of 0–100 nmol/L ( Ip = 0.116 2 CBaP + 22.926 2, R2 = 0.997 8), and the limit of detection (LOD) was 0.103 nmol/L (RSN = 3). The recoveries of benzo(a)pyrene in spiked sesame oil were in the range of 98.51%–100.57%. The results well agreed with those obtained by high performance liquid chromatography. The proposed method had good stability and repeatability and was characterized by simple sample pretreatment, short detection time, rapidity and low cost.

This study developed a simple, rapid and visual approach for colorimetric detection of organophosphorus pesticide. Positively-charged gold nanoparticles (AuNPs) with an average diameter of 25 nm were synthesized by seed growth method which possessed intrinsic peroxidase-like activity. AuNPs were demonstrated to have the highest oxidase activity at pH 4.0, 35 ℃ in the presence of 1 mmol/L 3,3’,5,5’-tetramethylbenzidine (TMB) and 10 mmol/L H2O2. It was shown that the nanozyme activity of AuNPs could be inhibited by its surface passivation with rogor, and so an inverse relationship between AuNPs catalytic activity and rogor concentration in the range from 1 to 80 mmol/L was found. The correlation coefficients and sensitivity of the assay were 0.985 and 1.39 mmol/L, respectively. Recoveries from tea samples spiked with different concentrations of rogor were in the range of 91.36%–102.56%. The effective peroxidase-like activity of AuNPs was kept for 1 month at room temperature. Adsorption of rogor onto AuNPs via amide bond was confirmed by Fourier transform infrared (FTIR) spectroscopic analysis. This assay may have potential application in environmental pollutant detection.

In order to protect the brand benefits of Wuchang rice, a total of 191 rice samples collected form Wuchang county and other places were identified by Fourier transform near infrared spectroscopy (FTNIS) combined with chemometrics. The results indicated that Wuchang rice and non-Wuchang rice were identified by factor analysis combined with FTNIS with 100% and 97.50% accuracy, by cluster analysis model with 100% and 100% accuracy, and by the quantitative analysis model developed using partial least squares (PLS) based on FTNIS spectra with 95.83% and 95.00% accuracy, respectively. It can be concluded that FTNIS combined with chemometrics is feasible to identify the geographical origin of Wuchang rice.

The total fluorine content and its forms in the whole body, head, shell and meat of Antarctic krill were analyzed using ultrasonic-assisted sequential extraction. The results showed that the total fluorine content in different body parts of shrimps was?in?the following order: shell > head > whole body > meat. For all the body parts, residual fluorine was the most abundant, followed by the exchangeable state; the contents of oxidized and organic fluorine were relatively low, and the content of water soluble fluorine was very low. Thus it was evident that fluorine in Antarctic krill mostly existed in the exchangeable and residual form. Correlation analysis showed a significantly positive correlation between water soluble fluorine and exchangeable fluorine (r = 0.495**). Fluorine in the oxidized state was significantly and negatively correlated with residual fluoride (r = ?0.254*). Organic fluorine and residual fluorine were positively correlated (r = 0.312*). There was also a significantly positive correlation of water soluble fluorine with pH (r = 0.737**) and moisture content (r = 0.292*). Organic fluorine and protein content showed a significantly positive correlation (r = 0.324*). Residual fluoride and protein content were negatively correlated (r = ?0.366*). This study can provide a scientific basis for understanding different forms of fluoride in different parts of Antarctic krill, and also provide a theoretical basis for the defluorination of Antarctic krill.

This study aimed to establish an accurate model based on fingerprint information fusion of characteristic volatile compounds and infrared spectrum for identifying the geographical origin of rice. A total of 20, 19 and 15 rice samples respectively collected from Panjin, Sheyang and Wuchang were analyzed for their volatile compounds by gas chromatography-mass spectrometry (GC-MS) and Fourier transform infrared spectra of these samples were recorded. Analysis?of variance (ANOVA) was employed to screen out the characteristic volatile components and characteristic infrared spectra, which were combined to establish a fingerprint information fusion model by partial least squares discriminant analysis (PLS-DA). The results showed that the identification accuracy of the fingerprint information fusion model was 97.4%, which was increased by 4.5% and 8.5% compared with individual infrared spectrum (92.9%) and volatile fingerprints (88.9%), respectively. Therefore, the PLS-DA information fusion model is feasible to identify the geographical origin of rice with high accuracy.

The viability of using near-infrared (NIR) spectroscopy to detect illegally added kojic acid (KA) as a browning inhibitor in wheat flour was studied. For this purpose, three common types of commercial flour, i.e., high-gluten flour, plain flour and low-gluten flour, were added with different amounts of KA (0.0%, 0.5%, 1.0%, 3.0%, 5.0%, and 10.0%), respectively. NIR spectra of all samples were collected in the wavelength range of 1 000–2 400 nm. For high-gluten flour samples, three common spectral preprocessing methods were compared with each other, as well as with non-preprocessing using partial least squares (PLS) regression. Savitzky-Golay derivative (SGD) was found to be the best preprocessing method. Then interval partial least squares (iPLS) was adopted to obtain optimized spectral interval in the wavelength range from 1 088.8 to 1 153.5 nm. The PLS model based on the optimal spectral interval showed better performance than that in the full wavelength range. Moreover, a PLS model was developed based on the optimal spectral interval for plain flour, low-gluten flour and a mixture of all three types, respectively. The models for all three types of flour and their mixture showed a determination coefficient (R2) of 0.949–0.972, a root mean square error (RMSE) of 0.581%–0.830%, and a ratio of standard deviation of the validation set to standard error of prediction (RPD) of 4.171–4.830. The model exhibited a good prediction performance for wheat samples with KA contents of 1.0%–10.0%. These results indicated that NIR spectroscopy could be used as an auxiliary method for precise chemical detection to improve the detection efficiency for massive samples.

In order to verify the accuracy of AKTS-SML software in simulating the migration of organic additives from single-layer plastic film into fatty food, five kinds of plastic films were chosen, and experimental data were selected from a large number of research publications. AKTS-SML software was used to simulate the migration processes and a comparison between the experimental and simulated values was made. It was found that setting up the plastic material specific parameter AP’ value used to calculate diffusion coefficient DP through the Piringer formula had a significant influence on simulated migration values. The results of simulated migration showed that at low temperature, AP’ values of most plastic materials were closer to their mean values, whereas they were closer to their extreme high values at high temperature. As a consequence, under different migration conditions, appropriate AP’ values gave SML software simulated migration values closer to the experimental ones. In addition, the initial contents of organic additives in plastic films and the thickness of plastic films and degradation of organic additives during migration also had influences on the simulation results. By analyzing several sets of experimental data from the literature, we found that AKTS-MLS software could simulate the migration of organic additives from single-layer plastic films to food simulants well in most cases. However, when organic additives were degraded during the migration process and their initial contents in plastic films were too high, the results of AKTS-SML software simulation deviated from the experimental results. Thus, further improvement is needed.

In this paper, a method for the simultaneous detection of pyraclostrobin and cymoxanil in cucumber and soil was developed using the quick, easy, cheap, effective, rugged and safe (QuEChERS) method coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The degradation kinetics and the final residue of pyraclostrobin-cymoxanil water dispersible granule in cucumber and soil were studied, aiming to evaluate the safety of this pesticide combination. Samples were extracted with acetonitrile and the extract was cleaned up with primary secondary amine (PSA) and C18 before being analyzed by mass spectrometry in the multiple-reaction monitoring (MRM) mode. There was a good linear relationship within the concentration range of 50–800 μg/L with correlation coefficients (R2) greater than 0.996 1. The average recoveries of two pesticides in cucumber and soil were 70.45%–107.08% at three spiked concentrations. The limit of quantification (LOQ) was 0.050 mg/kg for both. Two-year field experiments at three different locations showed that the residual concentrations of pyraclostrobin and cymoxanil were lower than the LOQ after 1 and 7 d, and 7 and 1 d after being applied at the high recommended 1.5-fold dose to cucumber and soil, respectively. When applied at the recommended dose 3 times to cucumber with a 7 d interval between each dose, the maximum residual concentrations of pyraclostrobin and cymoxanil were 0.090 and 0.060 mg/kg, respectively, which were lower than China’s maximum residue limits (MRL) for pyraclostrobin and cymoxanil in cucumber (0.5 mg/kg). The recommended safe pre-harvest interval was 3 d.

A method for the determination of 34 plant growth regulators in vegetables and fruits was established. Samples were pretreated by the quick, easy, cheap, effective, rugged and safe (QuEChERS) method after being ground. Five grams of the samples were extracted with 10 mL of acetonitrile, and dehydrated with a mixture of 4 g of MgSO4, 1 g of NaCl, 1 g of Na3Cit, 0.5 g of 2Na2HCit·3H2O. The supernatant extract was purified with different sorbents according to the state of samples. The analytes were separated on a Waters Acquity HSS T3 column with acetonitrile-water as the mobile phase using gradient elution, detected by mass spectrometry using electrospray ionization with piecewise scanning in the multiple-reaction monitoring (MRM) mode and quantified by the matrix-matched external standard peak area method. The calibration curves were linear in the concentration range of 2–100 μg/kg. The limits of detection (LODs) of 34 plant growth regulators were 2–10 μg/kg. The method was rapid, sensitive and precise, and could meet the requirements for the determination of plant growth regulator residues thereby providing technical support for regulation of plant growth regulator residues in common vegetables and fruits.

A method for determining the migration of Al, As, Ba, Cd, Cu, Fe, Mn, Ni, Pb and Zn from plastic drinking straws was established by inductively coupled plasma mass spectrometry (ICP-MS). The method presented good linearity with correlation coefficients of 0.999 9, and the recoveries were in the range of 88.7% to 98.3% with relative standard deviations (RSD) of 1.2% to 9.4%. Thus this method met the analytical requirements. The results for 71 samples of commercially available straws showed the migration amounts of Ba, Cu, Mn and Zn all conformed to the national standard Hygiene Standards of Uses of Additives in Food Containers and Packaging Materials (GB 9685-2008), while the migration amounts of Al, Ni and Pb exceeded the national standard limit according to Drinking Water Health Standards (GB 5749-2006) by 23.9%, 60.6% and 39.4%, respectively. In only a few samples the migration of Pb exceeded by 37.6 times. These results indicated that since metals could migrate from plastic drinking straws to the drink, regular use of plastic drinking straws poses potential safety risks.

A new method was developed for the determination of 30 polycyclic aromatic hydrocarbons (PAHs) in edible vegetable oils by gas chromatography-tandem mass spectrometry (GC-MS/MS) after freeze defatting. Six deuterium labeled PAHs were used as internal standards. Samples were extracted with acetonitrile-acetone (4:1, V/V) by vortex mixing in a centrifuge tube followed by 5 min centrifugation at 10 000 r/min and freezing at ?80 ℃ for fat solidification. The extract was evaporated in a rotary vacuum evaporator and blown to dryness under nitrogen. The residue was re-dissolved in dichloromethane, and detected using GC-MS/MS in the multiple reaction monitoring mode. The calibration curves for all the analytes showed good linearity (R2 > 0.998) in their respective concentration ranges. The limits of detection (LODs) and limits of quantitation (LOQs) for 30 PAHs were in the ranges of 0.10–1.83 and 0.35–6.11 μg/kg, respectively. The recoveries varied from 67.77% to 119.28% with relative standard deviation (RSDs) of 1.18%–12.47% (n = 6) at spiked levels of 5, 20 and 50 μg/kg. The levels of 30 PAHs in 38 commercial edible vegetable oil samples from 11 different species were investigated using the GC-MS/MS method. The results showed that naphthalene, 2-methylnaphthalene, 1-methylnaphthalene, biphenyl, 2,6-bimethylnaphthalene, acenaphthylene, acenaphthene, 2,3,6-trimethylnaphthalene, fluorene, dibenzothiophene, phenanthrene, anthracene, 1-methylphenanthrene, fluoranthene, pyrene, cyclopenta[c,d]pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[e]pyrene and benzo[a]pyrene were detected in all samples; the detection rates of 5-methylchrysene, perylene, indeno[1,2,3-c,d]pyrene, dibenz[a,h]anthrancene, benzo[g,h,i]perylene and dibenzo[a,l]pyrene were 86.84%, 63.16%, 81.58%, 21.05%, 81.58% and 26.32%, respectively; neither dibenzo[a,e]pyrene nor dibenzo[a,h]pyrene were detected in any of the samples. The total concentrations of 30 PAHs ranged from 92.56 to 905.16 μg/kg, and BAP varied from 1.94 to 7.40 μg/kg, which were at safe levels according to the limit standard.

This study aimed to characterize the traceability of soybeans with similar regional characteristics and improve the accuracy and stability of mineral elements in tracing the geographical origin of soybeans. In this experiment, inductively coupled plasma mass spectrometry (ICP-MS) was used to analyze the contents of mineral elements in 42 samples collected from 9 farms in Bei’an city and 6 farms in Nenjiang county, Heihe city, Heilongjiang province. The obtained data were analyzed by analysis of variance (ANOVA), principal component analysis (PCA) and discriminant analysis (DA). The results showed that the first principal component for these soybean samples mainly included V, Fe, La, Ce, Pr, Nd, Dy, Er and Yb, with largest contribution rate of 28.390%. The second principal component mainly included As, Se, Lu, Ir and Au, with middle contribution rate of 14.435%. The third principal component mainly included Ca, Ni, Cd and Ba, with smallest contribution rate was 10.881%. Thus, analysis of mineral content data was useful for tracing the geographical origin of soybeans from different producing areas in the province. Six metal elements, Na, K, Mn, Rb, Ba and Au, were identified as indicators for traceability analysis. Our results demonstrated that the geographical origin of soybeans from the two main producing areas in Heilongjiang province was identified with 100% accuracy.

To quickly obtain information about trace pesticides in Xinjiang grown apple, we investigated 7 commonly used pesticides during apple planting, and established a dispersive solid phase extraction combined with ultra performance liquid chromatography-high resolution tandem mass spectrometry (UPLC-HRMS/MS) method to quickly screen and quantitatively analyze the target pesticides. The results showed that good linearity was observed for all 7 analytes with correlation coefficients above 0.99. The limits of detection (LODs) were in the range of 0.003–0.1 mg/kg and the limits of quantification (LOQs) ranged between 0.02 and 0.5 mg/kg. Average recoveries were in the range of 95%–119% with relative standard deviation (RSD) less than 10% (n = 3). The method allowed for the rapid multi-residue analysis of pesticides in Xinjiang grown apples to be exported without any false-positive results.

In this study, a rapid, highly sensitive and selective method was developed for the simultaneous determination of residues of sulfoxaflor, pyrifluquinazon and spirotetramat in fruits (apple, grape, and strawberry) and vegetables (cucumber, onion, Chinese cabbage, spinach, and welsh onion) by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The target compounds were extracted from the samples with acetonitrile and cleaned up with dispersive solid phase extraction using primary secondary amine (PSA) and C18 as solid phase before being separated on a C18 column. Two pairs of precursor product ion transitions for sulfoxaflor, pyrifluquinazon and spirotetramat were measured and evaluated under the positive multiple reaction monitoring (MRM) mode. Matrix effects were tested by comparison of reference standards in pure solvent with matrix-matched standards of each matrix. In order to reduce the systematic error, quantification was performed using matrix-matched standard calibration curves. Satisfactory linearity in the concentration range of 0.2–100, 0.02–10 and 0.1–10 μg/L for sulfoxaflor, pyrifluquinazon and spirotetramat, respectively were obtained with correlation coefficients (r) of higher than 0.999 0. Average recoveries of sulfoxaflor, pyrifluquinazon and spirotetramat added to cucumber, grape, apple and scallion ranged from 79.9% to 103.9%, with relative standard deviations (RSD) from 3.3% to 8.8%. The limits of quantification (LOQs) were 0.334, 0.040 5 and 0.378 μg/kg, and the limits of detection (LODs) were 0.100, 0.012 2 and 0.133 μg/kg for sulfoxaflor, pyrifluquinazon and spirotetramat respectively. The method is quick, easy, effective, sensitive and accurate, and can meet the requirements for the determination of residues of sulfoxaflor, pyrifluquinazon and spirotetramat in fruits and vegetables.

A gas chromatography-tandem mass spectrometry (GC-MS/MS) method was developed for the analysis of organochlorine pesticides (OCP) and polychlorinated biphenyls (PCBs) in milk. Samples were?pre-processed with 30% sulfuric acid-methanol, and then extracted with n-hexane. The supernatant extract was puri?ed by a modi?ed quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction procedure, and the?purified extract was detected by GC-MS/MS and quantified by the matrix standard calibration curve method. The results showed that all the target analytes displayed good linear relationships in the range of 5–200 μg/L with correlation coefficients more than 0.99. The limits of detection (LODs) of OCPs and PCBs ranged from 0.1 to 0.3 μg/kg. The average recoveries of OCPs and PCBs from spiked samples were in the ranges of 85.5%–115.2%, with relative standard deviations (RSDs) less than 10% (n = 6). In summary, the proposed method due to its simplicity, high accuracy and ef?ciency could be used for the rapid screening and quantitative analysis of organochlorine pesticide and polychlorinated biphenyls in milk.

A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction method was developed for the simultaneous determination of 42 steroid hormones in milk and milk powder by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Sample pretreatment was studied and the detection conditions were optimized to obtain a rapid and accurate method. The steroid hormones from samples were extracted with 0.1% formic acid in acetonitrile followed by a salting-out step with anhydrous MgSO4 and NaCl. After centrifugation, the supernatant was cleaned up with 50 mg of octadecylsilane (C18), 100 mg of primary secondary amine (PSA), and 300 mg of aluminum oxide (Al2O3-N) and re-dissolved with 40% formic acid acetonitrile. The separation was performed on a Waters ACQUITY UPLC? BEH C18 column (2.1 mm × 100 mm, 1.7 μm) with gradient elution using acetonitrile and water containing 0.1% formic acid as the mobile phase. The electrospray ionization mass spectrometry was operated in the positive mode using multiple reaction monitoring (MRM). The target compounds were quantified by the matrix-matched external standard method. Under the optimal conditions, the calibration curves of all the analytes were linear in the concentration range of 0.5–500 μg/L with correlation coefficients larger than 0.99. The limits of quantitation (LOQs) ranged from 0.06–1.5 μg/kg. The average recoveries for milk and milk powder at three spiked levels ranged from 70.3%–118.1% with relative standard deviations (RSDs) of 0.6%–14.7%. The method due to its simplicity, rapidity, high accuracy and high precision was suitable for the simultaneous detection of 42 steroid hormones in milk and milk powder.