The effect of two different enzymes (maltogenic amylase and α-amylase) and two sucrose esters with different hydrophilic lipophilic balance (HLB) values (S-1670 and S-570) on batter interface properties and baking and storage characteristics of sponge cake. The results showed that the foaming ability and water-holding capacity of cake batter containing sucrose ester with an HLB value of 16 (S-1670) increased because of its decreased density and surface tension compared to the blank control. The low-filed nuclear magnetic resonance (LF-NMR) and differential scanning calorimetric (DSC) data showed that the system containing simultaneously both enzymes and sucrose ester S-1670 had shorter relaxation time T22 (4.501 ms) and lower staling rate (0.035 d-1) compared to 8.521 ms and 0.041 d-1 for that containing maltogenic amylase alone, thereby improving the quality of sponge cake after 35 d of storage at 4 ℃. Sucrose ester S-1670 exerted its effect during the first 21 days of storage, while the enzymes exerted their effect from day 21 to 35.

Folic acid-chitosan complex was applied to modify nanoliposomes containing curcumin. The average particle size and zeta potential of curcumin nanoliposomes were (67.4 ± 2.3) nm and (?13.81 ± 2.75) mV, and they were increased to (103.6 ± 4.1) nm and (16.35 ± 3.54) mV after being modified with folic acid-chitosan complex. The modified curcumin nanoliposomes showed better storage stability at 25 ℃ as compared to the native curcumin nanoliposomes and both of them possessed good sustained release property. Furthermore, curcumin was released faster from the modified nanoliposomes under weakly acidic conditions than under slightly alkaline conditions. Both the native and modified nanoliposomes without curcumin exhibited no cytotoxicity on Caco-2 cells, and the modified curcumin nanoliposomes possessed higher cytotoxicity than the native curcumin nanoliposomes, which was associated with higher cellular uptake percentage.

In this study, the enhancing effect of adding different amounts of oxidized tannic acid (OTA) on the oxidative stability of oil-in-water (O/W) emulsions prepared using porcine plasma protein hydrolysates (PPPH) as an emulsifier was investigated. Changes in peroxidation value (POV), conjugated diene (CD) value and thiobarbituric acid reactive substances (TBARS) value in the emulsions during storage were measured. We also determined changes in tryptophan fluorescence intensity and fluorescent protein oxidation products (FP) by fluorescence spectroscopy. The results showed that compared with the control group, the POV, CD and TBARS values significantly decreased with increasing addition of OTA from day 1 to 10 of storage (P < 0.05). This effect was positively correlated with OTA addition. Additionally, the tryptophan fluorescence intensity significantly decreased during storage (P < 0.05), while the FP significantly increased (P < 0.05). The changes in both parameters were dependent upon OTA concentration. Our results indicated that the quinine compounds of OTA could react with sulfhydryl and amino groups on peptide chains to form C—N and C—S bonds, promoting the cross-linking of peptide chains. The cross-linked peptides could be effectively wrapped around the surface of oil droplets, significantly improving the oxidation stability of the emulsions during the entire storage period. This study can lay a theoretical foundation for the application of OTA in food emulsion systems.

In this study, ultrasonication in combination with hydrogel setting was used to prepare β-carotene colloidal dispersions, and the color properties and stability of the dispersions were investigated. Results showed that the particle size of β-carotene in the aqueous phase decreased with ultrasonic time. Ultrasonication for 5 min could result in formation of colloidal particles with an average diameter of (164 ± 1) nm and apparently changed the color of dispersions. The aggregation of β-carotene particles could be inhibited effectively by kappa-carrageenan. A color-stable freeze-dried powder was obtained when the kappa-carrageenan concentration was above 0.8%. As the particle size was decreased, the chemical stability of β-carotene in the colloidal dispersions decreased during storage.

The effect of irradiation on pork muscle protein degradation was investigated. Low-dose irradiation (3 kGy) was applied on fresh pork hindquarter meat and the meat was evaluated for small molecular polypeptides and amino acid compositions derived from the degradation of various pork muscle proteins. The results showed that the contents of Leu, Ile, Met, Ser, Glu, Cys and Thr in irradiated samples decreased significantly compared to the control samples (P < 0.05), while the contents of Vla, Pro were not significantly changed after irradiation. The degradation degree of different muscle proteins during irradiation and their contribution to the formation of small molecular polypeptides were different. A total of 104 small molecular polypeptides (< 3 kDa) were produced in the irradiated pork meat, more than 50% of which were derived from myofibrillar proteins, 30.7% from titin, nebulin, and troponin T and I, and 22.2% from desmin, myotilin, LIM domain-binding protein 3 and actinin-associated LIM protein 1a. The generation of these small molecular polypeptides suggested that irradiation could influence the taste of meat products.

The effects of different saturation degrees and different amounts of fatty acids on the rheological properties and zeta potential of emulsions stabilized by salt-soluble protein extracted from pork Longissimus dorsi were studied. The results showed that the higher the amount of fatty acids was, the stronger the emulsifying activity of the emulsion was. But increased amount of fatty acids could cause more serious stratification of the emulsion. Addition of either oleic acid or linoleic acid could significantly increase the surface active sulphur content. The emulsion particle size distribution curves showed a single peak in a narrower range compared to the blank group. In addition, emulsion viscosity was decreased gradually and finally tended to be stable with the increase of shear rate. For each shear rate, the?shear stress?of the?emulsion increased with higher amount of fatty acids added. The charged particles were unstable as indicated by zeta potential values. In general, higher degree of saturation and higher addition level of C18 fatty acids resulted in better emulsification of C18 fatty acids with salt-soluble pork protein by improving protein membrane formation on the lipid droplet surface.

Soybean protein isolate (SPI) was subjected to ultrasonic pretreatment and then dry-heated with xylose (XYL) at a mass ratio 4:1 at 90 ℃ for 6 h to obtain Maillard reaction products (MRPs). The MRPs were subsequently used as the emulsifier and soybean oil was used as the dispersed phase to prepare emulsions in order to investigate the effect of ultrasonic treatment of SPI on its Maillard reaction with XYL and emulsifying properties of the resultant MRPs. The results indicated that ultrasonication of SPI significantly enhanced its Maillard reaction with XYL and improved the Zeta potential, fluorescence intensity and emulsifying activity of the MRPs. Measurements of particle size and creaming index illustrated that ultrasonication decreased the aggregation degree of MRPs-stabilized emulsions under varying conditions of ionic strength, temperature, and pH, but could not weaken the creaming of the emulsions as compared with native SPI.

In order to ascertain the effect of flaxseed gum (FG) on the emulsifying and gelling properties of minced meat, water loss rate, oil loss rate, texture properties, and the amount of protein load at the fat globule surface were measured and scanning electron microscopic examination was carried out as well as protein electrophoresis. It was found that salt reduction (from 0.6 to 0 mol/L) significantly increased water and oil loss rate (P < 0.05), deteriorated texture properties and reduced the amount of adsorbed proteins at the fat globule surface. On the other hand, flaxseed gum significantly enhanced the water- and oil-holding capacity (P < 0.05) and improved the network structure of gels. Besides, the addition of FG could increase the kinds and amounts of fat globule surface proteins and accordingly improve the emulsion stability. Therefore, a low-salt environment (0–0.4 mol/L) could result in quality deterioration of emulsified meat products whereas this effect could be abrogated by the addition of flaxseed gum.

The zeta potential, particle size and infrared spectroscopic characteristics of 11S glycinin under different heat treatment conditions were investigated. The absolute value of zeta potential was reduced with increasing heat treatment time at 80 or 90 ℃, while it decreased at first and then increased at 100 ℃. The average particle size of 11S glycinin was increased at all three temperatures. The absolute value of zeta potential was changed more significantly and the average particle size was larger at 100 ℃. The changes in zeta potential and average particle size were related to the alteration in the molecular structure of the protein after heat treatment. For 2% 11S glycinin solution, the transformation of β-turn and random coil structure might offset each other during heat treatment at 80 ℃, and finally α-helix was transformed into β-sheet structure. Heat treatment at 90 ℃ for 30 min resulted in the transformation of α-helix and β-sheet into β-turn structure, and the secondary structures were no longer converted to each other after 30 min. In the first 20 min of heat treatment at 100 ℃, α-helix and β-sheet were rapidly transformed into β-turn and random coil structure, and the secondary structures were not converted to each other from 20 to 45 min of heat treatment. After 45 min, the transformation was further strengthened.

ZnO films with different morphologies were prepared by the sol-gel method under vacuum conditions on the surface of porous titanium sheets with pores of 50 nm, and the thin films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), selected area electron diffraction (SAED) and hydrophily. The effect of the morphology of ZnO films on their anti-biofilm properties against the food spoilage bacterium Shewanella putrefaciens was determined. The results showed that ZnO had a hexagonal wurtzite structure, and the microstructure of ZnO thin films was affected by the number of coating cycles. The amount of ZnO deposited on the film with one cycle of coasting was low, and ZnO was firstly deposited on the edge of TiO2 porous. When the sol was deposited for 4 times, the amount of ZnO deposited was increased, and ZnO was packed densely along the top of channels. The porous titanium films were hydrophobic, and they became hydrophilic after the deposition of ZnO. The hydrophilicity of the films was strengthened with increasing number of coating cycles. As the porous titanium plate was hydrophobic, its anti-biofilm property against S. putrefaciens was stronger than that of ordinary titanium plate. However, because of the antibacterial properties of ZnO, the antibiofilm properties of the ZnO films were enhanced by sol-gel coating, and the ZnO film with 4 cycles of coating possessed the best antibiofilm properties.

Objective: To prepare a water-soluble polysaccharide and its iron complex from Radix Glehniae and to study their physicochemical properties, structural characteristics and biological activity. Methods: The polysaccharide was obtained by water extraction and alcohol precipitation and it was reacted with ferric chloride upon heating to synthesize polysaccharide-iron complex. The physicochemical properties and structural characteristics of the polysaccharides and its iron complex were determined by UV-Vis spectroscopy, infrared spectroscopy, high performance anion-exchange chromatography, transmission electron microscopy, and differential scanning calorimetry coupled with thermogravimetric analysis. The hydroxyl radical scavenging capacity and the inhibitory activity against α-glucosidase were also investigated. Results: The polysaccharide yield was 18.4%. The polysaccharide was composed of glucose and mannose with a molar ratio of 1.00:4.25. The polysaccharide-iron complex contained 19.31% iron ions, and it was based on polymerized β-FeOOH micronucleus as the core with surface complexation of polysaccharide. Both the polysaccharide from Radix Glehniae (GLP) and its iron complex (GLP-Fe) had hydroxyl radical scavenging activity and inhibitory effect against α-glucosidase, with the latter being more effective. Conclusion: The hydroxyl radical scavenging effect and α-glucosidase inhibitory effect of the water-soluble polysaccharide from Radix Glehniae were improved after being complexed with iron ions.

In this paper Raman spectroscopy was used to study the changes of protein structure and amino acid residue microenvironment in grass carp surimi during frozen storage. Grass carp surimi was frozen at ?18 ℃ for 2 or 8 weeks and then scanned with a Raman spectrometer. The amide III region, C—C, S—S, and C—H stretching vibration bands were analyzed as well in the variation in I850/I830 intensity ratio, and the secondary structures of proteins in the amide I region were quantified. The results showed that the protein backbone conformation was transformed from an ordered to disordered state. The contents of α-helix and random coil structure in fresh surimi were 34.31% and 13.47%, respectively, which decreased to 15.33% and increased to 30.89% after 8 weeks of frozen storage, respectively. The I850/I830 intensity ratio was 1.81, 1.89 and 1.99 for fresh, two-week-frozen and eight-week-frozen surimi, respectively. Tyrosine residues were exposed to the surface of polypeptide chains during surimi processing and this phenomenon was more significant after frozen storage. The conformation of some disulfide bonds was transformed from trans-gauche-trans to gauche-gauche-trans within 2 weeks of frozen storage. The Raman peak of C—H stretching vibration near 2 900?cm-1 was weakened whereas the hydrophobic interaction of aromatic amino acid side chains was enhanced. The structure of surimi proteins became disorderly and scattered with micro-environmental changes of amino acid residues during frozen storage.

In this study, protease was purified consecutively by ammonium sulfate precipitation, Q-HP anion-exchange chromatography and Superdux 75 gel chromatography. Matrix-assisted laser desorption/ionization-time of flight/time of flight (MALDI-TOF/TOF) mass spectrometry analysis suggested that the protease was highly similar to calpain RIM13, a cysteine protease from Aspergillus oryzae. The optimal temperature was 50 ℃ and the optimal pH was 6.5. The enzyme was stable at 40 ℃ and pH 7.0. It was activated by Mn2+, but inhibited by Fe3+, Fe2+, Cu2+, Ca2+, K+ and Na+. The metal ions affected its secondary structure. The Km and Vm values of the protease for casein were 2.43 g/L and 103.09 mg/(L·min), respectively. At NaCl concentrations of 5, 10 and 15 g/100 mL, the protease retained 77.22%, 54.39% and 41.15% of its initial activity, respectively. Consequently, the protease has potential industrial applications.

In this study, 16S rRNA high-throughput sequencing was used to study the bacterial community succession in fish sauce during its fermentation process. The results showed that number of bacterial species in fish sauce increased first, peaking (312 species) at month 6, and then decreased with prolonged fermentation time. Less abundant bacterial diversity and a smaller difference among the bacterial communities were observed from month 6 to 12 of fermentation. Firmicutes and Proteobacteria were the most dominant phyla during the whole fermentation process. Haloanaerobium was the most predominant genus, and its relative abundance increased first and then decreased with increasing fermentation time. The relative abundances of Photobacterium, Tetragenococcus and Halomonas were significantly increased during the mid to late fermentation stages compared with those at month 0. At the end of the 12-month fermentation period, Halomonas became the dominant genus. Gas chromatography-mass spectrometry (GC-MS) was used to study the volatile flavor components in fish sauce during the fermentation process. A total of 54 volatile flavor components including aldehydes, alcohols, ketones, esters, hydrocarbons, acids and nitrogen compounds were detected, and 9 key volatile flavor compounds were identified according to their odour activity value (OAV) ( ≥ 1). Pearson’s correlation analysis showed that Halanaerobium and Halomonas had a significant correlation with the changes in major volatile compounds. These results suggest that the bacterial community structure has an important influence on the formation of volatile flavor components in Chinese fish sauce.

Cross streak, radial streak, agar diffusion and co-culture methods were used to assess the antimicrobial activity of various probiotics and their metabolites against four representative foodborne pathogenic bacteria. The probiotic strains with great antibacterial activity against both Gram-positive pathogens (Listeria monocytogenes and Staphylococcus aureus) and Gram-negative pathogens (Escherichia coli and Salmonella typhimurium) were screened out. They were incorporated into polymeric materials (hydroxypropyl cellulose, glycerol and konjac flour) to develop bacteriostatic films, and the probiotic viability and the antimicrobial effects of films were measured. The consistent results obtained from cross streak and radial streak tests showed that Lactobacillus and Enterococcus especially Lactobacillus paracasei CICC 20241 exhibited high antibacterial activity against four target pathogens; the agar diffusion test showed that the lactic acid bacteria culture (LC), cell-free supernatant (CFS), and bacterial cells (BC) of L. paracasei CICC 20241 all had great antibacterial effect, and the co-culture test showed that L. paracasei CICC 20241 exhibited higher growth activity and antagonistic activity when inoculated earlier than the pathogens. In addition, the bacteriostatic film prepared in this experiment was a good carrier for L. paracasei CICC 20241, which was suitable for the survival of the Lactobacillus strain and exhibited continuous antibacterial activity against the target pathogens. The Lactobacillus film may have a great application potential for the development of packaging materials for fresh foods.

This study aimed to simultaneously and rapidly identify and count the common fermentation strains (Lactobacillus bulgaricus and Streptococcus thermophiles) and probiotic strains (Lactobacillu caseii, Lactobacillus acidophilus and Lactobacillus plantarum) in probiotic yogurt by hyperspectral imaging technology combined with plate colony method using pattern recognition. The obtained results were compared with those obtained by the traditional counting method to evaluate the feasibility of colony counting using hyperspectral imaging technology. It was shown that when nine principal components were used, the least square support vector machine (LS-SVM) model was superior to the K-nearest neighbor (KNN) and back-propagation artificial neural network (BP-ANN) models in identifying the different types of colonies. The recognition rate of the LS-SVM model was 99.20% and 93.33% for calibration and prediction sets, respectively. Thus, the LS-SVM model was the best counting model. No significant difference was observed between the two counting methods (P > 0.05), confirming the feasibility of using hyperspectral imaging technology to simultaneously count the number of each probiotic species in yogurt with mixed strains. The method overcame the defect of the traditional counting method which could not simultaneously count the number of each probiotic species in yogurt mixed strains, and therefore could provide the basis for rapid and non-destructive detection of the quality and health benefits of yoghurt.

A strain K-1 with carotenoid-producing potential was identified using morphological, physiological, biochemical tests and rDNA-ITS sequence analysis. A colorimetric method was used to determine mycelial growth and the stability of carotenoids produced by this strain. The fermentation conditions of strain K-1 were optimized by one-factor-at-a-time and orthogonal array design methods. The results indicated that K-1 was identified as Rhodotorula mucilaginosa. The optimum temperature for growth of the strain was 30 ℃, and it could be grown well in the initial pH range from 2 to 7. The characteristic absorption peak indicated that the acetone extract of cultured cells of K-1 contained torulene. The carotenoids produced by K-1 had good stability, but the stability was decreased under the conditions of high temperature (> 60 ℃), intense light and oxidant H2O2. The optimum fermentation conditions were determined as follows: glucose 20 g/L, (NH4)2SO4 20 g/L, anhydrous CaCl2 2 g/L, trisodium citrate 5 g/L, temperature 30 ℃, inoculum size 10%, shaking speed 150 r/min, medium volume 50 mL/250 mL, initial pH 5.5, and time 5 d. The yield of carotenoids on a dry mycelial mass basis was (180.14 ± 2.45) μg/g under the optimum culture conditions. Strain K-1 has the potential to produce a high yield of carotenoids, and the pigment produced by it has good stability. This strain represents a new microbial resource for carotenoids production.

The volatile flavor compounds of Chinese cabbage pickle fermented with Lactobacillus casei 11MZ-5-1, isolated from naturally fermented Chinese cabbage brine, and the naturally fermented sample were analyzed by high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). Meanwhile, the bacterial communities were investigated. It was found that L. casei 11MZ-5-1 fermented pickle contained higher total acid content and lower nitrite content than the naturally fermented one. The contents of the health-beneficial metabolites glycerine, mannitol, 2,3-butanediol and VC were (0.36 ± 0.03), (13.82 ± 0.42), (0.22 ± 0.02) g/L and (445 ± 13.23) mg/kg, respectively, and the relative content of flavor compounds was (91.13 ± 4.29)% in the L. casei 11MZ-5-1 fermented pickle, which were all higher than those in naturally fermented pickle (P < 0.05). These results demonstrated that the 11MZ-5-1 fermented Chinese cabbage pickle were better in term of safety and nutritious value in addition to higher contents of flavor compounds and better sensory quality. Furthermore, the bacterial diversity in the 11MZ-5-1 fermented product was lower than that in the naturally fermented sample (P < 0.05), and L. casei dominated the microbial flora during the fermentation process. Our findings highlight the application potential of L. casei 11MZ-5-1 as a starter culture for industrial production of Chinese cabbage pickle and could be useful for monitoring the production of pickled Chinese cabbage and establishing quality standard.

In the present study, Torulaspora delbrueckii WA19, isolated in our laboratory, was used for mixed-culture cherry wine fermentation with Saccharomyces cerevisiae F33 in order to elucidate the effect of mixed-culture fermentation on the quality of cherry wines. Wine fermentation with F33 alone and in combination with Viniflora Prelude, a pure strain of T. delbrueckii was used as control. Results showed that WA19 and F33 did not inhibit each other and they could rapidly adapt to the wine environment and proliferate. The whole fermentation process with WA19 and F33 took 8 d. However, F33 was antagonistic against Viniflora Prelude during mixed-culture fermentation. The mixed culture of WA19 and F33 significantly increased the synthesis of many aroma compounds, such as β-phenylethyl alcohol, ethyl butyrate, ethyl 3-methylbutanoate, ethyl hexanoate and linalool, enhancing the fruity, flowery and fermented aroma and making the aroma more appealing. Considering the advantages that WA19 possesses, it may have a great potential to be used in cherry wine production.

This study aimed to figure out the evolution of the microbial community in traditional Sichuan Paocai brine. A fermentation process model of Sichuan Paocai was proposed. The microbial community composition and diversity at different fermentation stages (from the first to twentieth generation) of Sichuan Paocai were detected by high-throughput sequencing. The results showed that seven bacterial phyla were found in the Paocai brine, Firmicutes (94.64%) and Proteobacteria (2.73%) being the dominant?ones. The fungal community mainly consisted of three phyla?and one unclassified population, among which Ascomycota was the dominant fungus (99.93%). There were seven bacterial genera with contents above 0.1% identified in the?Paocai brine, including Lactobacillus, Raoultella, Citrobacter and Lactococcus. The major fungal genus found was Kazachstania (more than 99%). Furthermore, this study showed that the diversity of bacteria and fungi in the?Paocai brine decreased with increasing generation of fermentation, and the microbial community gradually became stable, with Lactobacillus being the main bacterial genus and Kazachstania being the main fungus.

Clustered regularly interspaced short palindromic repeats (CRISPRs) are?an adaptive, heritable immune system found in prokaryotes that confers resistance to exogenous?genetic?elements?such as phage. CRISPRs are considered an ideal target for molecular subtyping because they have a high diversity and carry traceable genetic information. In this study, the genomic CRISPR structure in 86 strains of Campylobacter jejuni isolated in Jiangsu province was analyze by bioinformatic methods. The results showed that 36% of these strains contained CRISPRs in their genomes and 32 strains were found to have only one CRISPR 92–366 bp in length. The direct repeats detected in this study were identical to those in the CRISPR database. A total of 111 spacers were recognized and they were classified into 17 different clusters based on their sequences, 10 clusters of which have been previously recorded in the CRISPR db database while the 7 others were reported for the first time, consisting of 55 (49.5%) of the 111 spacers. Homology analysis showed that there was a high similarity in the spacer sequences between different phages and plasmids from the same genus or species as well as those from other pathogenic bacteria, which suggested that horizontal gene transfer (HGT) may play an important role in the bacterial communication between C. jejuni and other pathogens. Besides, 38 wild strains of C. jejuni were grouped into 5 patterns based on the CRISPR structure diversity. The results of this study can provide essential data for subsequent molecular subtyping and traceability of C. jejuni.

Partial fragments of the cytochrome oxidase subunit I (CO I) genes from13 species in 3 genera of puffer fish and 9 samples from unknown species collected in Fujian province and Hainan province were amplified by polymerase chain reaction (PCR) using universal primers and the PCR products were sequenced. The DNA sequences of 13 known species were submitted to the GenBank with accession numbers. The target gene sequence was 681 bp in length for all species. Sequence alignment was carried out using DNAMAN V6 software, and a phylogenetic tree among species was established. Thirteen known species were divided into 4 groups, with 84% homology between the groups and 90%–100% within the groups. Nine samples of unknown puffer fish species were classed into 2 groups: the Takifugu and Gastrophysus genera; HNW2 was identified as Gastrophysus lunaris, HNW3, HNW4, FJW2, and FJW5 as G. spadiceus, HNW1 as G. gloveri and FJW1, FJW3 and FJW4 as T. oblongus.

Objective: To evaluate the composition of microbial communities adhered to the surface of shrimp (Litopenaeus vannamei) under different conditions. Methods: Genomic DNA was extracted from bacteria adhered to the surface of live shrimp, fresh shrimp, fresh peeled shrimp and frozen peeled shrimp and was sequenced by using high-throughput sequencing. Results: 1) A total of 30 591–42 043 valid sequences and 68–168 operational taxonomic units (OTUs) were obtained from each sample, and the number of OTUs was lowest in frozen peeled shrimp and relatively high in live shrimp and fresh shrimp. 2) Among all samples investigated, frozen peeled shrimp exhibited the lowest ACE, Chao1 and Shannon indices and highest Simpson index, suggesting lower bacterial abundance and diversity. 3) At the family level, compared to live shrimp, the relative abundance of Moraxellaceae in fresh shrimp was significantly increased, which might be related to the death of shrimp and microbial contamination and growth; the abundance of Vibrionaceae in fresh peeled shrimp was significantly increased and the highest content was observed, which was caused by microbial contamination from the environment and the devices used during shrimp processing. The dominant spoilage bacteria in frozen peeled shrimp were Moraxellaceae, Pseudomonadaceae, and Listeriaceae. 4) Heatmap analysis showed that the similarity in bacterial flora between live shrimp and fresh shrimp was higher, whereas they were significantly different from fresh peeled shrimp and frozen peeled shrimp, indicating that the preparation of peeled shrimp and frozen storage had a great impact on shrimp bacterial flora. 5) Principal component analysis (PCA) indicated that there was significantly difference in microbial community composition between frozen peeled shrimp and other samples. Conclusion: There were significant differences in the dominant microorganisms, flora structure, abundance and composition among shrimp samples under different conditions. Different control processes are necessary for different types of shrimp products to ensure the quality and safety of shrimp products.

The bacterial community diversity, abundance and succession in chilled chicken were studied at different enrichment temperatures (4 and 37 ℃) by using Ion Torrent PGM high-throughput sequencing. The results showed that Proteobacteria, Firmicutes and Bacteroidetes were the dominant bacteria at the phylum level. At the genus level, Pseudomonas, Shewanellaceae and Acinetobacter were the dominant bacteria during the early stage of storage (0–4 d) with Pseudomonas accounting for the highest proportion (44.03%) upon enrichment at 4 ℃; during the middle and later periods of storage (6–12 d), Myroides increased rapidly and its content reached a level greater than that of Pseudomonas, which was identified as the dominant spoilage bacteria. At 37 ℃ enrichment temperature, Citrobacter, Proteus, Lactococcus and bacteria_p_other were predominant during the early stage of storage. During the middle and later periods of storage, Myroides and Wohlfahrtiimonas were the dominant spoilage bacteria, which significantly contributed to quality deterioration in chilled chicken. The changes in the bacterial community and diversity at the two enrichment temperatures could reflect the potential hygienic risk of chilled chicken. The results of this study provide a technical basis for effectively monitoring the quality and safety of chilled chicken during cold storage with and without temperature control.

In this study, a strain named H1 capable of producing citrinin (CIT) was isolated from rotten citrus and identified as Penicillium expansum. The effects of different culture media, temperature, pH value, culture time and dissolved oxygen on the mycelial growth and CIT production of strain H1 were explored. The results showed that when P. expansum H1 was cultured in yeast extract-sucrose liquid medium with an initial pH of 3 at 25 ℃ with shaking for 2 weeks, the CIT content reached the highest value of 12.8 μg/g, and the CIT production was inhibited at pH 11.

Pteridium aquilinum was subjected to solid-state fermentation with Fomes fomentarius, Ganoderma lucidum or Schizophyllum commune in order to investigate changes in the contents of total phenolics and total flavonoids and antioxidant and anti-inflammatory activities in vitro of the ethanol extract of P. aquilinum before and after the fermentation process. The results showed that the total phenolic and total flavonoid contents in the ethanol extract (PAEE) of P. aquilinum was significantly decreased and increased after fungal fermentation, respectively (P < 0.05). PAEE from non-fermented P. aquilinum had stronger scavenging capacities against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) free radicals. The half-maximal inhibition concentration (IC50) of non-fermented PAEE was (0.51 ± 0.02) mg/mL, while it was increased to (2.69 ± 0.01), (1.20 ± 0.14), and (0.92 ± 0.01) mg/mL after fermentation with F. fomentarius, G. lucidum, and S. commune, respectively. Both unfermented and fermented PAEE had no significant cytotoxicity in the concentrations range of 0–0.2 mg/mL. In addition, they were capable of inhibiting the production of nitric oxide (NO) in LPS-stimulated RAW264.7 cells in a dose-dependent manner, and the inhibitory effect of fermented PAEE was significantly stronger than that of non-fermented PAEE (P < 0.05). The inhibition percentage of NO production by non-fermented PAEE was 27.09%, while PAEE from P. aquilinum fermented with F. fomentarius, G. lucidum, and S. commune exhibited higher inhibition percentage of 58.61%, 63.57%, and 69.46%, respectively, at a concentration of 0.2 mg/mL. Total phenolic content demonstrated positive correlations with antioxidant activity for native and fermented PAEE. Moreover, significantly positive correlations were found between anti-inflammatory activity and total flavonoid content.

In this study, yeasts were isolated and purified from the traditional fermentation starter (Daqu) for Laobaigan liquor. The isolates were identified by morphology as well as polymerase chain reaction-restriction fragment length polymorphism?(PCR-RFLP) analysis of ribosomal 26S rDNA. Meanwhile, yeasts were identified by culture-independent method, namely polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Total DNA was extracted from Daqu and amplified by PCR. The PCR products?were fingerprinted by denaturing gradient gel electrophoresis (DGGE) and were excised and recovered from the gel. The results showed that a total of 57 strains of yeast assigned to 6 kinds of morphology were isolated by traditional culture method and were identified as Pichia kudriavzevii, Clavispora lusitaniae, Wickerhamomyces anomalus, Rhodotorula mucilaginosa, and Trichosporon asahii. A total of 10 strains of yeast were obtained by PCR-DGGE, including one strain of W. anomalus, one strain of Wickerhamomyces sp., one strain of T. asahii, one strain of Candida tropicalis, one strain of Candida sp. two strains of Hyphopichia burtonii and three strains of uncultured Saccharomycopsis. Ten yeast strains belonging to eight genera were identified by culture-dependent and culture-independent methods, including P. kudriavzevii, C. lusitaniae, W. anomalus, R. mucilaginosa, T. asahii, uncultured Saccharomycopsis, H. burtonii, Wickerhamomyces sp., C. tropicalis, and Candida sp.. The results from this study provide a basis for further study on the fermentation performance of Daqu .

The aim of this study was to construct a DNA fingerprint for identifying different malt varieties based on tailed primer M13 microsatellite (TP-M13-SSR) markers. Four simple sequence repeat (SSR) primer pairs with high polymorphisms were successfully screened out from 163 candidates, and an average of 6.75 genotypes were detected using each SSR primer pair, on average with 3-10 alleles. In the case of massive primer screening, the use of M13 universal primers could greatly reduce the cost of fluorescent tags of SSR primers. After analysis of alleles, four selected primer pairs could distinguish 23 malt varieties using specific alleles, and a DNA fingerprint database was established for the different malt varieties investigated in this study. In conclusion, this method was cheap, accurate and reliable, and it could provide technical support for breweries to purchase malt.

Free, conjugated, and bound phenolic acids in ten vegetables and vegetable products, including cow pea, broccoli, soybean sprouts, eggplant, potato, cucumber, spinach, Chinese cabbage, potato, and ketchup were identified and quantified by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The results indicated that phenolic acid contents varied greatly among the vegetables. Of all the vegetables, Chinese cabbage contained the highest levels of free phenolic acids, while the highest amount of conjugated phenolics was determined in cow pea, followed by spinach, which showed the highest levels in bound phenolic acids. Principle component analysis (PCA) revealed some key compounds that could differentiate among these vegetables. p-Coumaric acid was identified as a characteristic component of cow pea. Ferulic acid and isoferulic acid were characteristics components that could differentiate spinach from the other kinds. In addition, sinapic acid was found to be a characteristic substance in cabbage. The results from this study can contribute to the development and application of functional components of vegetables.

Objective: To provide a scientific basis for the development and utilization of the roots of Panax ginseng C.A. Meyer cv. Silvatica. Methods: The effects of different forest types, producing areas, ages and slope orientations on the contents of ginsenosides in the roots of P. ginseng C.A. Meyer cv. Silvatica. were evaluated. Simultaneous determination of 20 ginsenosides was performed by high performance liquid chromatography (HPLC). Results: A total of 14 ginsenosides were detected in each sample regardless of forest types, producing areas, ages or slope orientations. The contents of ginsenosides Rg1, Re, Rf, Rb1, Rb2, Rb3 and Rg5 and the total content of 20 ginsenosides in the samples grown in the forest of Pinus sylvestris var. Mongolica were the highest among four forest types investigated. The contents of Rg1 and Rf in the samples from Lushuihe township, Fusong county were the highest among six producing areas. Among three different ages, the contents of Rg1, Rf and Rb1 of the 15-year-old samples were the highest, while the contents of Compound K and protopanaxadiol (PPD) were the highest in the 5-year-old samples. Among three different slope orientations, the contents of Rb2 and Rb3 in the samples from south-facing slope were the highest, while the content of Rh2 in the samples from north-facing slope was the highest. Conclusion: The contents but not types of ginsenosides in the roots of P. ginseng C.A. Meyer cv. Silvatica varied with different forest types, producing areas, ages and slope orientations. The roots of P. ginseng C.A. Meyer cv. Silvatica aged 5 to 15 years could meet the requirements of Chinese Pharmacopoeia (CP, 2015 version).

The effect of electron beam irradiation at doses of 1, 3, 5, 7, and 9 kGy on the sensory score, volatile flavor and relative odor activity value of crab meat (Ovalipes punctatus) was evaluated. Sensory evaluation showed that the smell of crab meat was changed after irradiation. The sensory score decreased with the increase of irradiation dose. Electronic nose analysis showed a significant difference in flavor between crab meat irradiated at 7 and 9 kGy but not between the samples irradiated at 1, 3, and 5 kGy. The results of gas chromatography-mass spectrometry (GC-MS) showed that 55 volatile flavor compounds were found in crab meat and the number increased to 60, 57, 62, 60 and 58 after irradiation at 1, 3, 5, 7, and 9 kGy, respectively. However, irradiation had almost no impact on the key volatile flavor compounds of crab meat or the volatile compounds that could modify the flavor of crab meat. In conclusion, the smell of crab meat can be maintained under electron beam irradiation at doses lower than or equal to 5 kGy, but irradiation at 7 and 9 kGy will cause slight off-odor.

In this study, the volatile components in loquat flesh from 7 white-fleshed cultivars and 15 red-fleshed cultivars were determined by head-space solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrophotometry (GC-MS). Then the volatile compounds were analyzed and classified by principal component analysis (PCA) and cluster analysis (CA). The results showed that the classes of volatile compounds detected in the flesh of ripe loquat from 22 cultivars were aldehydes, olefins, alcohols, ketones, esters and other compounds. Aldehydes were the main volatile components of loquat flesh. Esters, ketones, and alcohols were important characteristic flavor components in different cultivars of loquat. Hexanal was the most abundant volatile compound. A total of 65 volatile components were identified from 7 white-fleshed cultivars, 14 of which were common to the cultivars. Camphene, caryophyllene oxide and 2-methyl- butanoic acid were found to be unique to the white-fleshed cultivars. A total of 81 volatile components were detected from 15 red-fleshed cultivars with 10 of them being common to these cultivars. Dimethyl heptenal, E-2,4-decadienal, E-β-ocimene, 3-carene, butanediol, Z-3-hexenol, 1-dodecanol, phytosterone, hexyl acetate, methyl salicylate, linalyl butyrate, methyl geranate, neryl acetate, ethyl cinnamate, thymol, and eugenol were uniquely found in the red-fleshed cultivars. Loquats with different flesh colors differed mainly in alcohols and esters. The contents of apo-carotenoids including β-cyclic citral, geranyl acetone, and β-ionone in red-fleshed loquat were significantly higher than those in white-fleshed loquat. PCA and CA classified all white-flesh cultivars except ‘Guanyu’ and ‘Wugongbai’ into one group. Nonanal made the highest contribution to the flavor of loquat flesh.

The nutrient compositions of the muscle and hepatopancreas of hard- and soft-shell crabs (Scylla paramamosain) were comparatively analyzed by nuclear magnetic resonance (NMR) based metabolomics. The results showed that when compared to hard-shell crabs, soft-shell crabs at 0 h postmolt had significantly lower levels of lysine, arginine, lactate and trimethylamine-N-oxide (TMAO) in muscle. The decreased levels of lysine, arginine and lactate may have little impact on the nutritive value and taste of crab muscle, whereas the decreased level of TMAO may reduce the risk of illness in consumers. Furthermore, the significant fluctuations of four amino acids and betaine in the hepatopancreas of soft-shell crabs at 0 h postmolt likely affected the taste of hepatopancreas. The muscle and hepatopancreas of soft-shell crabs at 3 h postmolt showed more significant changes in nutrient composition. Especially, there was a significant decline in 5’-adenosine monophosphate (AMP) in muscle, presumably affecting the umami taste. Moreover, the levels of histidine, tyrosine and glucose in hepatopancreas were significantly decreased from 3 h postmolt, likely reducing the nutritional value of this tissue. Therefore, newly molted soft-shell crabs might have nutritional value similar to that of hard-shell crabs in terms of the composition of low molecular mass nutrients, being a healthier aquatic product. However, delayed harvest may affect the quality and taste of soft-shell mud crabs.

The nutrient composition (protein, fat and moisture) and physicochemical properties (ash, pH and color) of Zhedong salted goose and braised goose were determined and compared. In addition, sensory evaluation was carried out and the major volatile substances were analyzed by electronic nose and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The results showed that the contents of protein, ash and fat and L* value of salted goose were significantly higher than those of salted goose (P < 0.05), while the differences in water content and pH were not significant. In terms of sensory evaluation, the quality of both products was good. However, in terms of flavor, the sensory score of braised goose was significantly higher than that of salted goose (P < 0.05). A total of 63 volatile flavor compounds were identified from salted goose mainly including aldehydes, ketones and alcohols, with 2,4-pentadiene being the most important one; 2-methyl-3-octanone and 1-octylene-3-alcohol also had a significant contribution to its specific flavor. Braised goose was found to contain 71 volatile components mainly including ketones, aldehydes and pyrazines, with ketones being the most abundant ones. Pyrazines were uniquely detected in braised goose. 2-ethyl-3-hydroxy-tetrahydropyranone, nonanal and tetramethylpyrazine were important for the formation of roast flavor. The results of this study are of great significance to the processing of salted goose and braised goose.

In order to correlate the changes in amino acid content with nutritional value and flavor quality during the ripening process of olive fruit, we applied high performance liquid chromatography-tandem mass spectrometry to quantitatively analyze the contents of free and hydrolytic amino acids in the olive cultivars ‘Changying’ and ‘Qinglan 1 hao’. The results showed that a total of 16 hydrolytic amino acids were detected in each cultivar, including 7 essential amino acids and 9 non-essential ones. However, the contents of total hydrolytic amino acids in the two cultivars were different; ‘Changying’ olives showed an increase-decrease-increase trend, while ‘Qinglan 1 hao’ olives presented a decrease-increase-decrease-increase trend. The cultivars were undesirable in terms of ratio of amino acid (RAA), ratio coefficient (RC) and score of ratio coefficient (SRC), leading to nutritional imbalance. The total free amino acid content in ‘Changying’ olives exhibited an increase-decrease-increase-decrease trend, whereas the opposite was observed for ‘Qinglan 1 hao’ olives. Each cultivar contained 19 free amino acids, with sweet and umami amino acids being the major ones, and sweet (Gln) and umami (Glu, Asp, and Asn) amino acids made a substantially greater contribution to ‘Qinglan 1 hao’ olives than to ‘Changying’ olives. Thus, the ‘Qinglan 1 hao’ cultivar had better sweet and umami flavor than the ‘Changying’ cultivar. The results from this study provide a basis for judging the flavor of olives.

This study aimed to investigate the effects of solvents with different polarities on the compositions and contents of free and bound phenolics as well as antioxidant activities in hulless barley grains. In the present study, four different solvent mixtures were used to extract free phenolic compounds from 4 varieties of hulless barley. Alkaline and acidic hydrolysis methods were compared for the hydrolysis of bound phenolic compounds from hulless barley. The phenolic compositions of the free and bound fractions were identified by high performance liquid chromatography (HPLC). The antioxidant activities were determined by 1,1-diphenyl-2- picrylhydrazyl (DPPH) and 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate (ABTS) radical scavenging capacity and ferric ion reducing antioxidant power (FRAP) assays. The results showed that 80% aqueous acetone extracted the largest amount of total free phenolic compounds (139.79–235.96 mg/100 g) and total free flavonoids (9.88–15.52 mg/100 g) from hulless barley of the solvents tested. The acidic hydrolysis method released 1.9–3.1 and 1.3–2.9 times more bound phenolics and flavonoids than the alkaline method. Eight to eighteen phenolic compounds were detected in the aqueous acetone extract of hulless barley, and its phenolic content was significantly higher than three other extracts. Chlorogenic acid, benzoic acid, catechin, quercetin, and rutin were identified as main free phenolic compounds. The types and amounts of bound phenolic compounds released by the acid hydrolysis method were higher than those achieved by the alkaline hydrolysis method. Gallic acid, p-coumaric, syringic acid, benzoic acid, 3, 4-dimethoxybenzoic acid, and hesperidin were found to be main bound phenolic compounds. The 80% aqueous acetone extract showed the highest DPPH (852.56–1 484.18 μmol/100 g) and ABTS+· (358.93–518.09 μmol/100 g) scavenging capacity and the highest FRAP value (1 250.55–2 041.16 μmol/100 g) of the four extracts tested. The DPPH scavenging capacity, FRAP values and ABTS+· scavenging capacity of the bound phenolic compounds obtained by acid hydrolysis were 7.6–10.3, 1.2–1.8, 1.1–1.3 folds higher than those obtained using the alkaline hydrolysis method. The free and bound phenolic contents and profiles and antioxidant activities of the extracts were found to be dependent on the extraction solvent used. Conclusively, 80% aqueous acetone and the acid hydrolysis method were suitable for extraction of free and bound phenolic compounds from hulless barley. Hulless barley exhibited high antioxidant activity and could be a potential natural source of antioxidants.

The flavor and bioactive components of pure honeysuckle flower liquor produced by solid-state fermentation were investigated and the important aroma compounds were analyzed by headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). The results showed that the flower liquor mainly contained β-damaconen, ethyl octanoate, acetal, ethyl 3-methylbutyrate, linalool, phenylethyl alcohol, ethyl decanoate, isoamyl acetate, ethyl laurate, ethyl caproate, acetaldehyde, olebellene, isoamyl octanoate, 2-methylbutanol, trans-eugenol, and other flavor compounds. Its flavor was similar to that of Fen-flavor liquor and the liquor had the characteristic flavor of honeysuckle flowers. Functional components such as chlorogenic acid were detected in the liquor. During the solid-state fermentation process, the aroma and bioactive components of honeysuckle flowers were retained and transferred to the liquor, enhancing the flavor and functional properties.

A spectrophotometric method was developed for the quantitative determination of γ-aminobutyric acid (GABA) in mulberry leaf tea. The absorbance of GABA was measured with a microplate reader at 640 nm wavelength, and the linearity of the calibration curve was satisfactory (R2 > 0.99). The average recovery rates of the colorimetric and HPLC methods were 98.46% and 100.10%, with an average relative standard deviation (RSD) of 1.28% and 0.37%, respectively. Both methods could accurately quantitatively determine GABA. Student’s t-test analysis showed that there was no significant difference between the two methods. Mulberry leaves and mulberry leaf tea exhibited no difference in GABA content as determined by colorimetry. The colorimetric method proved to be simple and rapid and was more suitable for large-scale determination of GABA.

In this experiment, salting-out followed by aqueous two-phase extraction was applied to purify papain from Hainan-grown papaya fruit. The crude enzyme was precipitated by a two-step salt-outing method with optimized saturation degree of (NH4)2SO4 of 20% and 45%, respectively. Using one-factor-at-a-time method and response surface methodology with a three-factor and three-level Box-Behnken design, the optimized conditions for aqueous two-phase extraction were determined as follows: [C4mim]N(CN)2 concentration 29.76%, (NH4)2SO4 concentration 16.08% and pH 8.18. Under these conditions, the extraction efficiency of papain was 89.01% and the specific activity of the purified enzyme was 1 056 U/mg with 86.72% recovery and 10.6-fold purification. The purified enzyme contained a significantly reduced number of impurity bands, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), suggesting good purification efficiency.

To reduce the allergenicity of soybean milk powder, soybean milk after removal of okara was treated by ultra-high pressure (UHP) followed by restriction enzyme hydrolysis instead of the traditional wet process for producing soybean milk powder. Using one-factor-at-a-time and orthogonal array design methods, the optimum process parameters were determined as follows: 15 min UHP treatment at 320.00 MPa and then 60 min hydrolysis with 0.3 U/g of flavourzyme. The allergenicity of soybean milk powder produced under the optimized conditions was reduced by 88.09%, but it tasted slightly bitter. To improve the taste, further blending is needed. The combination of UHP and enzymatic hydrolysis synergistically significantly enhanced the in vitro protein digestibility and reduced the allergenicity of soybean milk powder. This synergistic effect was further confirmed by measurement of in vitro protein digestibility, protein dispersibility index and allergen content and SDS-PAGE analysis.

The enzymatic extraction of flavor compounds from Agaricus bisporus was investigated. In this paper, four different protease, neutral protease, papain, protamex and flavourzyme were compared for their efficiencies in hydrolyzing Agaricus bisporus. The results indicated that the hydrolysate from flavourzyme contained significantly higher contents of soluble solid and flavor amino acids than the hydrolysates obtained with other proteases. Besides, flavourzyme could remove the bitterness and astringency and maintain the umami taste of the hydrolysate while enhancing the saltiness and making it richer in taste. The hydrolysate was clear and transparent. Therefore, flavourzyme was selected as the best enzyme and the conditions including hydrolysis time, temperature, pH and enzyme dosage were optimized based on free amino acid concentration using one-factor-at-a-time method and an L9?(34) orthogonal array design (OAD) with four factors at three levels. The hydrolysis efficiency was highly significantly affected by temperature and significantly affected by pH. The optimal conditions for enzymatic hydrolysis were found to be as follows: enzyme dosage 1 000 U/g, pH 6.5, temperature 60 ℃, time 3 h. The hydrolysate prepared under the optimized conditions contained 140.27 mmol/L free amino acids and could be used as base seasoning.

In this study, a method for the determination of cadmium (Cd) in edible oil samples was established using extraction induced by emulsion breaking combined with inductively coupled plasma mass spectrometry (ICP-MS). The key parameters affecting the extraction efficiency including surfactant type, surfactant concentration, nitric acid concentration, and sample mass were carefully examined and optimized, and the optimized conditions were applied to determinate edible oil samples. The use of Triton X-114 at a concentration of 0.09 g/mL, a nitric acid concentration of 5% (V/V) and 2.0 g of samples were found to be the optimal conditions. The limit of detection (LOD) was 0.031 ng/g for Cd with a correlation coefficient over 0.999 9, and the recoveries were in the range of 90.3%?105.0%. There were no statistical differences between the results obtained by extraction induced by emulsion breaking and by the traditional microwave digestion method. The extraction induced by emulsion breaking procedure is a simple, fast and green sample pretreatment method, which could be utilized for the rapid and accurate determination of cadmium in edible oils by ICP-MS.

For rapid and non-destructive detection of sulfur content in honeysuckle, the flowers of Lonicera japonica Thunb., hyperspectral imaging technology combined with chemometrics was applied to develop a predictive model for detecting sulfur-fumigated honeysuckle with different sulfur concentrations. Hyperspectral images of non-fumigated and sulfur-fumigated honeysuckle samples with four concentration gradients of 0%, 0.5%, 1% and 1.5% on a fresh mass basis were collected and preprocessed by Savitzky-Golay smoothing filter (S_G filter), multiple scatter correct (MSC) or standard normal variate transformation (SNV). S_G filter was selected as the optimal pretreatment method. Subsequently, the processed spectral data were used to establish models using either fisher discriminant analysis (FDA) or kernel Fisher discriminant analysis (KFDA), and the results showed that KFDA had a better discrimination accuracy of 98.2%. Considering that the full-range spectral data contain a great deal of redundancy, the characteristic wavelengths were extracted by three different methods, regression coefficients (RC), Wilks criterion and RC-Wilks. As a result, the discriminant models, RC-KFDA, Wilks-KFDA and RC-Wilks-KFDA were developed. A comparison was made between these models, and the RC-Wilks-KFDA model was found to be the best one with the highest discrimination accuracy of 100%, good classification efficiency and short running time of 0.69 s. Therefore, the S_G-RC-Wilks-KFDA model could allow fast, effective and non-destructive detection of sulfur content in honeysuckle.

The purpose of this work was to study the enantioselective behavior of chiral pesticide flutriafol during strawberry growth and winemaking. Strawberries were sprayed with flutriafol before harvest to determine the effect of wine processing on flutriafol residues. The enantiomers of flutriafol were separated and determined by ultra-performance convergence chromatography-tandem mass spectrometry (UPCC-MS/MS). The results indicated that no obvious stereoselective behavior was observed for flutriafol enantiomers during strawberry growth. The half-lives of (-)-R-flutriafol and (+)-S-flutriafol were 13.80 and 13.60 d, respectively. (+)-S-Flutriafol degraded faster than (-)-R-flutriafol during the wine fermentation process. The half-lives of (-)-R-flutriafol and (+)-S-flutriafol were 38.06 and 29.90 d for the washed group, and 29.31 and 22.14 d for the unwashed group, respectively.

A multiplex polymerase chain reaction (mPCR) assay was developed and validated for simultaneous detection of Staphylococcus carnosus, S. xylosus, S. saprophyticus, S. epidermidis, S. equorum and S. sciuri, which are commonly found in fermented meat products. In this study, six pairs of species-specific primers were designed targeting the gap, rpoB, SodA and SNc genes, and the PCR reaction system was optimized. The results showed that The sensitivity of the mPCR system was 4 pg for bacterial genomic DNA and 2 × 102 CFU for living cultures. Meanwhile, eight Staphylococcus strains from traditional fermented meat products were consistently identified by this mPCR assay and 16S rDNA sequence and biochemical analysis. This mPCR method was species-specific and effective, and could be used in the rapid and accurate identification of S. carnosus, S. xylosus, S. epidermidis, S. equorum, S. sciuri and S. saprophyticus. Thus, it has great application prospects.

In this paper, the fluorescence properties of laccaic acid A and the factors affecting them were investigated. In order to develop a new method to detect laccaic acid A, its metal ion recognition capacity was evaluated. The results showed that the chemical properties and polarity of the solvent used to laccaic acid A, concentration and pH on affected the fluorescence intensity and emission wavelength of laccaic acid A. Cu2+, Fe3+, Fe2+, and Pb2+ quenched the fluorescence intensity of laccaic acid A, while Zn2+ and Al3+ led to fluorescence enhancement. Notably, Al3+ showed significant specificity. Other metal ions had little effect on the fluorescence intensity. In the presence of Al3+ (0.04 mol/L), the fluorescence intensity of laccaic acid A was linear with its concentration. The application results showed that laccaic acid A could be detected in two different beverages by a fluorescence method with Al3+ as the standard solution. The recovery rates of the method were between 95.0% and 109.3%, with relative standard deviations (RSDs) in the range of 1.9% to 5.4%. This new method has great potential for practical application.

A high performance liquid chromatography (HPLC) method for the determination of four penicillin residues in foods of animal origin was developed.?Ampicillin trihydrate was used as the internal standard. Samples were extracted with a mixture of acetonitrile and water (10:1, V/V), and the extract was then cleaned up on an HLB solid-phase extraction cartridge. Penicillin G, oxacillin, nafcillin and dicloxacillin were separated on a C18 column by gradient elution with a mobile phase consisting of monopotassium phosphate (0.02 mol/L) and acetonitrile. The calibration curves were linear over the concentration range of 0.01–2 μg/mL with correlation coefficients of more than 0.999. The limits of detection (RSN > 3) (LOD) and quantification (RSN>10) (LOQ) were 3 and 10 μg/kg for all the analytes, respectively. The average recoveries were between 69.9% and 100.3% with relative standard deviations (RSDs) of 1.58%–9.15% (n = 6). The method is simple, rapid, sensitive and accurate and can meet the requirements for practical analysis. It has been applied with satisfactory results to detect penicillin residues in pork, beef, chicken and fish.

In this study, 4 single nucleotide polymorphisms (SNPs) were screened out and identified by sequencing for the discrimination of 7 malt varieties. Furthermore, discrimination profiles were also established using SNP based kompetitive allele specific PCR (KASP) assay. Quantitative analysis of known mixed samples was carried out using the KASP assay with a relative error less than 3% between the measured and actual values. The KASP assay is useful for the enrichment of malt SNP fingerprint database.

In this paper, a zinc-based metal organic framework, [(Me2NH2)2Zn3(fdc)4]n·DMA (Zn-MOF), was prepared from 2,5-furandicarboxylic acid and Zn(NO3)2·6H2O in N,N-dimethylformamide (DMF) under solvothermal condition. Fluorescence spectroscopic analysis revealed that the material showed emission maxima at 379 and 398 nm. The effects of 16 metal ions often coexisting in foods on the fluorescence intensity of the material were explored. The results indicated that Fe3+ could selectively quench the fluorescence of the material. In addition, the effects of Fe3+ concentration, soaking time and metal ion mixtures (Fe3+-M+/2+/3+) on the sensitivity of fluorescence quenching were also investigated. Our results showed that Zn-MOF exhibited high selectivity for Fe3+. Thus, this Zinc-based metal-organic framework material could be used as a fluorescent probe for the determination of Fe3+ in foods.