The stability of Pickering emulsion stabilized by solid lipid particles (SLPs) is directly impacted by changes in its crystal structure. The mechanism behind the effect of changes in the crystal structure of palm stearin (PS) as an ideal raw material for SLPs on Pickering emulsion stability is still unknown. In this study, PS-SLPs with different crystalline structures (size, crystal shape and morphology) (T40-PS-SLPs and SC-PS-SLPs) were prepared by adding 0.5%–5% of Tween 40 (T40) or sodium caseinate (SC), and oil-in-water (O/W) Pickering emulsion stabilized by SLPs was successfully constructed. Moreover, the relationship between the crystalline structure of the PS-SLPs and the stability of O/W Pickering emulsion stabilized by them was investigated. The findings indicated that most T40-PS-SLPs were lath-like particles with a particle size range of 124.1–370.1 nm, and the major crystal structure was type β’, while SC-PS-SLPs were type β’ irregular spherical particles with a particle size range of 309.7–346.2 nm. After sonication, both T40-PS-SLPs and SC-PS-SLPs wrapped 10% corn oil to form stable O/W Pickering emulsion; the average droplet size of the emulsion prepared with T40-PS-SLPs ranged from 0.76 to 2.23 μm and the lipid crystals in the emulsion were predominantly type β, while the emulsion prepared with SC-PS-SLPs showed average droplet sizes ranging from 0.81 to 1.27 μm and most lipid crystals were type β’. It was found that during the preparation of Pickering emulsion, the crystal form of T40-PS-SLPs changed from sub-stable type β’ to stable type β, while the crystal form of SC-PS-SLPs did not change significantly. After 60 days of storage, it was found that the Pickering emulsion prepared with T40-PS-SLPs containing more than 1% of T40 and that prepared with SC-PS-SLPs containing more than 1% of SC were stable for at least 30 days. Overall, the emulsion prepared with type-β’ irregular lath-like T40-PS-SLPs with small particle size showed better storage stability. This study provides some data support for the development of O/W Pickering emulsion stabilized by lipid-based solid particles.

In this study, natural soybean oil body emulsion and pectin were combined by electrostatic deposition for the preparation of soybean oil body-pectin composite oleogel by emulsion template method. The macro- and micro-structures of soybean oil body-pectin composite oleogel were studied, and the average particle size, zeta potential, oil binding capacity, re-dissolution stability, rheological properties, texture properties and oxidative stability were analyzed. The results showed that the average particle size and zeta potential of the composite emulsion containing 1.0% of pectin (m/m) were both smallest and were 423.13 nm and −23.23 mV, respectively. Cryoscanning electron microscopy (Cryo-SEM) showed that with an increase in pectin concentration, the structure of the sample was more compact, the hardness of the freeze-dried sample increased, and the gel strength of the oleogel increased; it showed shear thinning and good thixotropy. In addition, the addition of pectin could significantly improve the oxidative stability of oleogels. Notably, the oleogel containing 1.0% or more of pectin had good re-dissolution stability, and the average particle size and zeta potential of the obtained emulsion were not significantly different from those of the initial emulsion. The three-dimensional network structure was restored to its initial state after dilution and shearing with the same mass of distilled water, and this process was reversible. Therefore, the new stable oleogel prepared with soybean oil body is a potential alternative to artificial solid fat.

In order to enhance the inhibitory effect of wheat gluten (WG) on the hygroscopicity of freeze-dried apple powder and to improve its storage quality, ethyl cellulose (EC), with low hygroscopicity, was selected to substitute for WG in different proportions in the production of freeze-dried apple powder. The effects of WG and EC on the hygroscopic behavior, macromorphology and moisture migration of freeze-dried apple powder were studied. The results showed that at 75% relative humidity, the equilibrium moisture content of freeze-dried apple powder decreased by about 2.26% for every 10% increase in EC addition. The Peleg model had the best fitting effect on moisture adsorption isotherms of freeze-dried apple powder, which belonged to type III. In addition, macroscopical photographs and low field-nuclear magnetic resonance analysis of freeze-dried apple powder showed that the optimal ratio of apple pulp to WG to EC was 7:2:1. This ratio not only had a certain inhibitory effect on the hygroscopicity of freeze-dried apple powder, but also avoided an increase in the proportion of free water caused by excessive addition of EC, which was conducive to keeping freeze-dried apple powder in a good powder state.

Emulsion gels (EG) and bigels (BG) were prepared by high-speed shear treatment of a mixture of beewax oleogels with pure water or κ-carrageenan hydrogel in the absence of emulsifiers, respectively. The effect of κ-carrageenan on the microstructure, physical stability, water- and oil-binding capacity, hardness, rheology and thermal properties of EG with different mass fractions of oleogel (40%, 60% and 80%) was investigated. The results showed that EG and BG were water-in-oil (W/O) type. Compared with EG, the addition of κ-carrageenan did not change the beeswax crystal type, oil-binding capacity or thermal properties of BG, but could improve the plasticity, water-binding capacity, physical stability, hardness and viscoelasticity of BG. In addition, with an increase in oleogel concentration in BG, the average size and size distribution range of dispersed aqueous droplets became smaller and narrower, and the shear resistance improved gradually.

In order to improve the bioavailability of resveratrol (Res), resveratrol was encapsulated in recombinant human heavy-chain ferritin (rHuHF) by ultrasonic treatment. rHuHF-Res were characterized, the interaction between Res and rHuHF was analyzed, and the antioxidant properties of rHuHF-Res were evaluated in simulated gastrointestinal juices. The results showed that approximately 22 resveratrol molecules could be encapsulated in one ferritin molecule with an encapsulation efficiency of 11.25%. Transmission electron microscopicy (TEM) results showed that resveratrol was encapsulated into the cavity of ferritin. The particle size of rHuHF-Res composites was not different from that of rHuHF as when detected by a laser particle size analyzer. The cavity of ferritin could protect Res from photothermal degradation. The results of ultraviolet visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, fluorescence spectroscopy and circular dichroism (CD) spectroscopy showed that ferritin and resveratrol could interact through hydrogen bonds and other forces. After digestion, the superoxide anion radical and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity of the composites were significantly higher than those of resveratrol (P < 0.05). The ferritin-resveratrol nanoparticles have good photothermal stability and antioxidant property, which provides a certain theoretical basis for its future development and utilization.

The effects of different concentrations (0.05%, 0.1%, 0.15%, 0.2%, and 0.25%) of resveratrol (RE) on the structural properties, rheological properties and gel properties (gel strength, water retention, water mobility, whiteness and microstructure) of silver fish myofibrillar protein were investigated. RE was found to combine with myofibrillar protein molecules, resulting in an increase in the particle size. Ultraviolet (UV) absorption spectra and intrinsic fluorescence spectra showed that the addition of RE changed the spatial conformation of myofibrillar protein and reduce its fluorescence intensity. The rheological results showed that the addition of RE increased the storage modulus and loss modulus of myofibrillar protein. As the amount of added RE increased, the gel strength first increased and then decreased. The addition of 0.15% of RE increased it by 38.43% compared with the control group. In addition, the addition of RE also improved the texture properties of the gel and increased the whiteness. Low-field nuclear magnetic resonance (LF-NMR) analysis showed that the addition of RE transformed part of the free water into immobilized water, enhancing the water-binding capacity of the gel. Scanning electron microscopy (SEM) showed that the addition of RE promoted the formation of a denser gel network. These results show that when added at an appropriate level, RE could interact with silver carp myofibrillar protein to change its conformation, thereby enhancing the gel properties of myofibrillar protein and forming a dense gel network structure. The results of this study can provide a reference for improving the gel properties of freshwater fish surimi and the quality of surimi products.

In this study, gelatin/zein/thymol nanofibers were fabricated by electro-blown spinning technique, and its microscopic morphology and diameter distribution were characterized by scanning electron microscopy (SEM). The interaction between protein and thymol was studied by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, and thermal analysis techniques in order to elucidate the changes in macroscopic performance such as mechanical properties and water vapor permeability (WVP) as well as antioxidant activity and antimicrobial property. Compared with traditional electrospinning, the yield of nanofibers was increased by 10.0 times using electro-blown spinning, and the feeding rate was increased from 1.0 to 10.0 mL/h. The diameter of gelatin/zein/thymol nanofibers showed an upward trend with increasing thymol loading (0%, 0.1%, 0.5%, and 1.0%). FTIR spectroscopy showed that thymol interacted with protein through hydrogen bonding, and no characteristic diffraction peak for thymol was observed in the XRD profile, indicating that thymol was uniformly distributed in the nanofibers. Nanofibers encapsulated with 0.5% thymol showed better WVP than thymol-free nanofibers, indicating that due to its hydrophobicity, thymol could prevent water molecules from passing through the nanofibers. Tensile tests showed that the addition of thymol significantly increased the elastic modulus of the nanofibers, but had no significant effect on the tensile strength or elongation at break. The antioxidant capacity of the nanofibers, as determined by radical scavenging and metal ion reducing assay, was correlated with the concentration of thymol. The nanofibers had potent antimicrobial effect against Escherichia coli and Staphylococcus aureus as evaluated by the zone of inhibition method.

The micromorphology and functional properties of aerogels from rice, pea, potato or corn starch were characterized by a scanning electron microscope (SEM), an automatic surface area and pore size analyzer, an X-ray diffractometer, and a texture analyzer. The findings revealed that all the four starch aerogels had low density and high porosity. Under SEM observation, rice starch aerogel showed a lamellar structure, pea and potato starch aerogels showed a porous structure with uneven pore size distribution and thick pore walls in some zones, and corn starch aerogel presented a good three-dimensional network structure. The average pore sizes of the four starch aerogels were not much different, mainly distributed in the range of 5–13 nm, whereas there were differences in specific surface area, being smallest in pea starch aerogel (0.330 m2/g) and largest in corn starch aerogel (0.562 m2/g). The X-ray diffraction results showed that the crystallinity of these four starches declined after gelatinization and retrogradation, with corn starch experiencing the greatest decrease, from 30.71% to 8.13%. Compared with pea and potato starch aerogels, corn starch aerogel had higher solubility, water absorption rate, and Young’s modulus (6.233 MPa), and showed stronger deformation resistance, indicating excellent aerogel performance.

This study was conducted in order to explore the effect of lead (Pb) stress on the nutritional value and flavor of barley seedling powder. Fourier transform infrared (FTIR) spectroscopy and targeted metabolomics based on liquid chromatography-mass spectrometry (LC-MS) were used for quantitative and qualitative analysis of protein secondary structure and amino acid contents in barley seedling powders with and without Pb stress during growth. The results showed that Pb stress led to the transformation of protein secondary structure in barley seedlings from disordered (β-turn and random coil) to ordered (α-helix) structure. Through high-throughput targeted metabolomic analysis, a total of 25 amino acids were identified and quantified in barley seedling powder. Pb stress decreased the contents of Arg, Pro and His, but increased the content of Val, which proves that Pb could reduce the nutritional value and sweetness, and increase the bitterness of barley seedling powder. These results provide some basic data for the development of barley-based health foods.

The effects of different temperature-time regimes of enzymatic retrogradation on the particle size, microscopic morphology, crystal structure, functional groups and epigallocatechin-3-gallate (EGCG)-loading capacity of debranched starch nanoparticles (DBS-NPs) prepared with green banana starch were investigated. Meanwhile, the stability, antioxidant properties and in vitro release behavior of EGCG@DBS-NPs were investigated. It was shown that compared with green banana starch, the particle size of DBS-NPs decreased from (23.4 ± 7.3) μm to (208.5 ± 2.7) nm, and the crystal structure changed from type C to C→B or C→A. Besides, the relative crystallinity and the hydrogen bonding force between molecular chains were enhanced. EGCG showed the highest loading capacity (4.34%) and encapsulation efficiency (86.89%) in DBS-NP50-12, and their combination exhibited synergistic antioxidant activity. EGCG@DBS-NP50-12 was found to be more stable in a near neutral environment than in an acidic environment, and significantly more stable than free EGCG during storage. EGCG@DBS-NP50-12 exhibited excellent slow release behavior in vitro, which was fitted to a first-order kinetic equation. This study provides a reference for the preparation and application of starch nanoparticles, which has potential value in the construction of starch-based bioactive carriers.

In this study, an ethanol extract from P. chinense Pursh was obtained by ultrasonic-assisted extraction, whose contents of total flavonoids and phenols were (17.43 ± 1.41) mg/g and (14.78 ± 0.95) mg/g, respectively. In total, 43 major chemical compounds were identified in the extract by ultra-high performance liquid chromatography-quadrupole-time of flight-mass spectrometry (UPLC-QTOF-MS). In addition, the effects of 0.05%, 0.1% and 0.3% P. chinense Pursh extract or 0.02% butylated hydroxyanisole (BHA) combined with butylated hydroxytoluene (BHT; 1:1, m/m) on lipid oxidation and protein stability in Chinese sausage were studied. The acid value (AV), peroxide value (POV), thiobarbituric acid reactive substance (TBARS) value, carbonyl content, sulfhydryl content and total volatile basic nitrogen (TVB-N) content of Chinese sausage were determined at different storage times. It was found that the TBARS value of the sausage with 0.3% P. chinense Pursh extract was significantly lower than that of the control group (0.02% BHA + BHT) on the 35th day, and the protein carbonyl and sulfhydryl contents and TVB-N content of the sausage with P. chinense Pursh extract were similar to those of the control group. Although the AV and POV of the P. chinense Pursh extract group were slightly higher than those of the control group, its lipid oxidation resistance was significantly better than that of the control group. Therefore, as a potential candidate to replace synthetic antioxidants, P. chinense Pursh extract has the potential to be used in the production of Chinese sausage for its positive effect on improving the product quality and extending the shelf life.

In order to prevent fucoxanthin degradation in the stomach before entering the intestine, pH-sensitive nanoparticles based on fucoidan and chitosan were constructed for the efficient delivery of fucoxanthin in the gastrointestinal environment. In this study, fucoxanthin and a fucoidan fraction were extracted from Sargassum horneri. High performance liquid chromatography (HPLC) was used to determine the purity of fucoxanthin. High performance gel permeation chromatography (HPGPC), chemical methods and HPLC were used to determine the molecular mass, physicochemical characteristics and monosaccharide composition of the fucoidan fraction. Fucoxanthin-loaded nanoparticles with different fucoidan/chitosan mass ratios of 0.6:1, 0.8:1 and 1:1 were prepared by polyelectrolyte self-assembly. Fourier transform infrared (FTIR) spectroscopy was used to evaluate the interaction between fucoidan and chitosan, and the physicochemical characteristics of fucoxanthin-loaded nanoparticles and the changes in its size, fucoidan-loading rate, and fucoxanthin-loading rate during simulated gastrointestinal digestion were determined to evaluate the stability of the nanoparticles in the gastrointestinal tract. Results indicated that the purity of fucoxanthin from S. horneri was 13.57%. The average molecular mass of the fucoidan was 342 kDa. The contents of total sugar, protein, uronic acid and sulfate group in it were 52.45%, 7.96%, 9.25% and 19.26%, respectively. Moreover, the fucoidan was composed of fucose, galactose, mannose, glucuronic acid and xylose, among which fucose and galactose were the most abundant monosaccharides. FTIR spectra showed non-covalent interactions between fucoidan and chitosan in the nanoparticles and good binding state between them. The particle size of fucoxanthin-loaded nanoparticles was 360–430 nm, the zeta potential was 26–31 mV, and the polydispersity index (PDI) was 0.23–0.27, indicating that the nanoemulsion was uniform and stable. The fucoidan-loading rate was 87%–90%, and the fucoxanthin-loading rate was 87%–91%, indicating that fucoxanthin was well encapsulated in the nanoparticles. In vitro simulated digestion experiments showed that the particle size, fucoidan-loading rate and fucoxanthin-loading rate of the nanoparticles in simulated gastric juice did not change significantly, indicating that the nanoparticles were stable in simulated gastric environment. In simulated intestinal fluid, the particle size increased significantly, and the fucoidan-loading rate as well as fucoxanthin-loading rate decreased significantly, indicating the expansion and depolymerization of the nanoparticles in simulated intestinal environment. As a result, efficient delivery of fucoxanthin in simulated gastrointestinal tract was accomplished. At the fucoidan/chitosan mass ratio of 1:1, the effect was most obvious.

Purpose: To investigate the binding interaction of astaxanthin with the transmembrane transporter protein cluster determinant 36 (CD36). Methods: Molecular docking was used to simulate the binding interaction between astaxanthin and CD36, the interaction parameters were obtained using an algorithm, the number of binding sites was determined, and the best matching model was established. Moreover, surface plasmon resonance (SPR) was used to measure the binding and dissociation constants of intermolecular interactions. Results: Astaxanthin entered the hydrophobic cavity inside CD36, and the docking binding energy was −11.70 kcal/mol, suggesting a dose-dependent effect. Besides, the equilibrium dissociation constant KD was 1.00 × 10-6 mol/L, indicating that astaxanthin bound to CD36 with high affinity, and the kinetic curves showed that the binding mode of astaxanthin and CD36 was slow binding and slow dissociation. Astaxanthin bound to more amino acids of CD36 through hydrophobic interaction. Unlike lutein and β-carotene, which formed weak van der Waals force with the polar amino acid Asn53 of CD36, astaxanthin formed hydrogen bonding with Asn53, which may be partly responsible for the high-affinity binding between astaxanthin and CD36. Furthermore, it was inferred that the ketone group on the terminal ring of astaxanthin or α-hydroxy ketone formed by hydroxyl and ketone groups played a certain role in the formation of hydrogen bonds. Conclusion: Astaxanthin interacts spontaneously with CD36 with high affinity, and the binding mode is slow binding and slow dissociation, contributing to efficient transmembrane transport.

In this study, the effect of citronellal on the synthesis of ergosterol in the spores of imazalil-sensitive (Pds01) and imazalil-resistant (Pdw03) strains of Penicillium digitatum was investigated. The results showed that citronellal significantly inhibited the spore germination of Pds01 and Pdw03 with half maximal inhibitory concentration (IC50) of 0.8 and 3.2 µL/mL, respectively. Citronellal at its IC50 significantly decreased and increased the contents of ergosterol and lanosterol in Pds01 and Pdw03 spores, respectively. The expression of key genes involved in ergosterol synthesis was significantly affected. The up-regulated expression of the ERG9 gene in Pds01 peaked earlier than that in Pdw03, and the expression level of ERG3 was significantly down-regulated in both strains. This study showed that citronellal reduced ergosterol synthesis in Pds01 and Pdw03 spores by inhibiting ERG3 expression, thereby affecting spore germination, which could provide a theoretical basis for the development of green preservatives for postharvest citrus diseases.

To explore the metabolic pathways involved in oligosaccharide synthesis during the fruit development of Lycium barbarum, we investigated the differential expression of oligosaccharide synthesis-related proteins at different developmental stages of L. barbarum (S1—young fruit, S2—green fruit, S3—early yellowing, S4—late yellowing, and S5—full fruiting) using isobaric tags for relative and absolute quantitation (iTRAQ). A total of 1 799 differentially expressed proteins were identified, 133 of which were found to be associated with oligosaccharide metabolism by Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. Oligosaccharide accumulation in L. barbarum fruits at the first three stages was mainly dependent on photosynthesis. Changes in the biosynthesis and metabolism of oligosaccharide were mainly related to the gene and protein expression of sucrose synthase (SS), sucrose phosphate synthase (SPS) and hexokinase (HK). At stages S4 and S5, oligosaccharide accumulation was achieved through the metabolism of starch and polysaccharide and the enzymes related to changes in the biosynthesis and metabolism of oligosaccharide included raffinose synthase, β-fructofuranosidase and endoglucanase. The gene expression of 10 oligosaccharide biosynthesis-related enzymes as detected by real-time polymerase chain reaction (PCR) was consistent with the proteomics results. This study provides a theoretical basis for further elucidating the mechanism of oligosaccharide biosynthesis and metabolism during the fruit development of L. barbarum.

In order to explore the relationship between dehydrin (DHN) and core browning in late-harvested Yali pears, this study identified and characterized the PbDHN3 gene based on bioinformatics methods, and analyzed the expression pattern of this gene during the core browning process under rapid cooling and slow cooling conditions. The results showed that the open reading frame (ORF) of PbDHN3 was 564 bp in length, encoding 187 amino acids, and having a conserved domain of dehydrin superfamily comprising two Y segments, one S segment and three K segments (Y2SK3). Bioinformatics analysis showed that PbDHN3 was a hydrophilic stable protein with a molecular mass of 19.77 kDa and an isoelectric point of 7.98. The secondary structure consists of α-helix, irregular coil, extended chain and β-turn. PbDHN3 was located in the nucleus and contained no signal peptide or transmembrane structure. It was a non-secretory protein. The results of homology analysis showed that PbDHN3 was more than 89.74% similar to the DHN of five other plants such as apples. Phylogenetic analysis showed that PbDHN3 had the closest relationship with the DHN of Pyrus ussuriensis × Pyrus communis. The results of promoter analysis showed that PbDHN3 contained basic promoter elements and other cis-acting elements, which were consistent with the predicted results of the upland cotton GhDHN1 and the wheat TaDHN2 promoter regions, and all of them included hormone response elements and light response elements. The results of real-time fluorescence polymerase chain reaction (PCR) analysis showed that the expression of the DHN3 gene was significantly up-regulated during the core browning process of Yali pears under rapid cooling conditions, which was closely related to the browning of the core. This study provides a theoretical basis for further exploring the function of the PbDHN3 gene and clarifying the mechanism of core browning of Yali pears.

Soluble dietary fiber (SDF) was extracted from Sargassum hemiphyllum fermented with Aspergillus niger or Aspergillus oryzae in order to investigate the effect of fungal fermentation on the yield, structural improvement, functional properties and antioxidant activity of SDF from S. hemiphyllum. The results showed that SDF prepared by fermentation with the two strains had advantages over each other. Compared with the untreated control group, A. oryzae fermentation increased the yield of SDF by 3.625 times, and the obtained SDF, which was bright in color and loose in structure, had higher purity and lower molecular mass (6.3 kDa), and consequently higher water-holding capacity (WHC) and sodium cholate adsorption capacity. A. niger fermentation increased the yield of SDF by 3.375 times, and the molecular mass of the obtained SDF was 39.4 kDa, which had a porous structure and significantly improved water-holding capacity, cholesterol and sodium cholate adsorption capacity. In vitro antioxidant experiments showed that fermentation improved the hydroxyl radical scavenging capacity of SDF, and decreased its scavenging capacity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical and oxygen radical. In summary, this study can provide a reference for the preparation of SDF by fungal fermentation and its development and application in functional foods.

In this study, Lactobacillus plantarum (Lp), Lactobacillus fermentum (Lf) and Weissella confusa (Wc) were selected as exogenous strains for the fermentation of sourdough. The growth of lactic acid bacteria, the distribution of major metabolites such as organic acid and sugar, and the distribution of protein in sourdough were evaluated by high performance liquid chromatography (HPLC) and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Finally, the sourdough was applied to the production of frozen dough bread. The results showed that in the sourdough, the bacteria entered the logarithmic growth phase at 4–12 h, and mixed cultures grew better than individual ones, showing synergism. Particularly, the colony count of Lf + Wc in sourdough was as high as 9.18 (lg(CFU/g)) after 12 h fermentation, and a large amount of fructose (11.82 mmol/kg) and extracellular polysaccharide (EPS) (3.132 g/kg) were generated. Compared with the other groups, Lf + Wc exhibited moderate acid production rate, lower protease activity and slower protein degradation rate. The baking quality of bread made from Lf + Wc fermented sourdough frozen and stored for 13 weeks decreased slightly, and the baking loss rate decreased only by 5.3%. In addition, GC-MS analysis showed that the number of volatile compounds in frozen dough bread fermented with Lf + Wc increased by eight after 13 weeks of frozen storage. In conclusion, Lf and Wc have a good synergistic effect when used together. Notably, metabolites such as exopolysaccharides generated during metabolism are of great significance for delaying and controlling the deterioration of frozen dough bread quality. This study provides a certain theoretical basis for the application of multigrain sourdough as a natural antifreeze agent in the large-scale preparation of frozen dough.

In order to obtain peptide fractions, duck liver proteins were recovered by isoelectric precipitation, and then hydrolyzed simultaneously by alcalase and flavorzyme. The molecular mass distribution of the hydrolysate was determined by using a gel permeation chromatography (GPC) system followed by fractionation using a combination of gel filtration chromatography (GFC) and reversed phase-high performance liquid chromatography (RP-HPLC). Ten novel peptides with molecular mass less than 1 300 Da were identified from the subfraction with high inhibitory effect on cytokine release from macrophages using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The anti-inflammatory activity of the synthetic peptides was tested in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells. Peptides LVYPFPGPI and VIESPPEI inhibited the release of NO from inflammatory cells in a dose-dependent manner, with inhibition percentages of 48.24% and 56.32% at the concentration of 100 μg/mL, respectively. VIESPPEI at the concentration of 100 μg/mL inhibited TNF-α release by 42.48%. Notably, IDVSPDSPDHY showed the strongest ability to inhibit the release of IL-6, with an inhibition percentage of 27.04% at the concentration of 25 μg/mL. This study may provide new ideas for the high-valued comprehensive utilization of duck by-products and their application in safe treatment of inflammation.

In order to study the enzymatic properties of laccase derived from Lactobacillus and its potential application in biogenic amine degradation, the gene encoding laccase from Lactobacillus plantarum was heterologously expressed and the recombinant laccase was enzymatically characterized. The optimum reaction temperature and pH, the effects of metal ions and chelators on laccase activity, the tolerance of the recombinant laccase to different concentrations of ethanol and the degradation of biogenic amines by the recombinant laccase were determined. The results showed that the optimum reaction temperature and pH of the purified recombinant laccase was 40 ℃ and 4.0, respectively. Low concentrations of Mg2+, Zn2+ and Ca2+ could promote the activity of the recombinant laccase in different degrees, Zn2+ and Ca2+ being most effective. On the contrary, high concentrations of Mn2+, Fe2+ and ethylenediaminetetraacetic acid could inhibit the activity of recombinant laccase by 85% or more. Toward the substrate 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), the Michaelis constant and maximum reaction rate of the recombinant laccase were 2.49 mmol/L and 0.22 mmol/(L·min), respectively. In addition, the recombinant laccase had a good tolerance to ethanol at low concentration, and the residual activity was more than 75% after incubation in 20% (V/V) ethanol for 1 h. The degradation rates of tyramine and tryptamine by the recombinant laccase were both 100%, while the degradation rates of spermidine, phenethylamine and histamine were 49.60%, 25.27% and 21.80%, respectively. Based on the above results, the recombinant laccase from L. plantarum has great application potential in the degradation of biogenic amines in low-alcohol fermented beverages and fermented foods.

In order to explore the flavor characteristics of strong-flavor baijiu base liquor in different seasons and different distillation stages, their organic acids and volatile components were analyzed using high-performance liquid chromatography and headspace solid-phase micro-extraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS). The results showed that the contents of total acid and four major acids (caproic acid, acetic acid, lactic acid and butyric acid) in the second stage of distillation were lower than those in the third stage. The contents of total acid and all four organic acids in base liquor were higher in spring and summer than in autumn and winter. A total of 108 volatile compounds were detected, and the total content of volatile flavor substances in the second stage of distillation was higher than that in the third stage. The content of esters in the second stage was higher, while the contents of acids and ketones were lower. In different seasons, the content of alcohols in base liquor in decreasing order was as follows: spring > summer > autumn > winter, and the content of acids was higher in spring and summer than in autumn and winter. As the seasons went on, the content of aldehydes in base liquor increased in the second stage, but decreased in the third stage. Using partial least squares-discriminant analysis (PLS-DA), a classification model for volatile compounds in base liquor samples collected in different seasons and different distillation stages, which proved to be quite efficient. According to variable importance in the projection (VIP > 1) from the model, the key differential compounds were identified to characterize the volatile composition of strong-flavor baijiu. These results can provide data support for the adjustment of the distillation process in strong-flavor baijiu production in different seasons.

To identify the key odorants in Amomum tsaoko cobs (ATC) before and after enzymatic treatment, solvent extraction (SE) followed by solvent-assisted flavor evaporation (SAFE) combined with gas chromatography-mass spectrometry-olfactometry (GC-MS-O) was used to extract and analyze volatile components in ATC. A total of 82 compounds were identified, including 32 odor-active compounds. Quantitative analysis was conducted by the internal standard method, and the concentrations of odor-active compounds in fresh ATC, and ATC treated by cellulase, β-glucosidase or their mixture were 237 562.17, 220 738.79, 296 759.57 and 284 809.47 μg/kg, respectively. Based on their concentrations and thresholds, odor activity values (OAVs) were calculated, and 19 odorants with OAV equal to or greater than 1 were determined as the key odorants of ATC. The numbers of key odorants in fresh ATC, and ATC treated by cellulase, β-glucosidase or their mixture were 16, 15, 16 and 15, respectively. Because of their different key odorants, the extracts had different odor characteristics. Different enzymes should be selected for the extraction of aroma components from ATC according to practical needs.

In order to explore the effect of dietary supplementation of Clostridium butyricum on the volatile flavor substances in the meat of small-tailed Han sheep during postmortem aging and its possible mechanism, the Longissimus dorsi muscle of small-tailed Han sheep slaughtered at the age of six months was taken for postmortem maturation at 4 ℃, and then the volatile flavor substances, the contents of lipid metabolism-related enzymes including adenosine monophosphate activated protein kinase (AMPK), acetyl CoA carboxylase (ACC) and carnitine lipoyltransferase 1 (CPT1) were measured on days 0, 1, 2, 3, 4 and 5. The results of electronic nose test showed that the contents of alkanes, hydroperoxide and nitrogen oxides in the C. butyricum supplementation group were higher than in the control group without C. butyricum supplementation. According to the results of gas chromatography-mass spectrometry (GC-MS), the types of aldehydes, alcohols and ketones in the C. butyricum group were more than in the control group, while the contents of fatty oxidation products such as octanal, nonanal, decanal and heptaldehyde were obviously reduced. The key flavor substances common to both groups, as determined by relative odor activity value (ROAV), included octanal, nonanal, trans-2-decenal and 1-octen-3-ol, nonanal being the greatest contributor to the flavor of lamb meat. Compared with the control group, the contents of AMPK and CPT1 in the C. butyricum group decreased significantly during postmortem aging (P < 0.05), while the contents of ACC in the C. butyricum group were significantly higher than those in the control group at 0, 1, 3 and 5 days postmortem (P < 0.05). The correlation analysis showed that AMPK and CPT1 were significantly positively correlated with nonanal (P < 0.001), while ACC was significantly negatively correlated with nonanal and decanal (P < 0.001). In conclusion, the addition of C. butyricum to the diet can affect the volatile flavor substances in the meat of small-tailed Han sheep during postmortem aging by regulating the AMPK-ACC-CPT1 signaling pathway.

In order to evaluate the effect of spices on the storage quality of thermal reaction-derived flavorings, the volatiles of beef flavoring produced by thermal reaction with and without the addition of spices were analyzed by solid phase microextraction (SPME) or solvent-assisted flavor evaporation (SAFE) combined with gas chromatography-olfactometry-mass spectrometry (GC-O-MS), and the aroma quality was investigated by sensory evaluation. Results revealed that 217 and 163 volatile compounds were identified by SPME and SAFE, respectively, mainly including aldehydes, ketones, terpenes, phenols, sulphur-containing compounds and nitrogen-containing compounds. Nitrogen-containing or sulphur-containing compounds with low odor thresholds were the key volatile aroma active compounds (flavor dilution factor ≥ 27, and odor activity value ≥ 1). Correlation analysis indicated that eucalyptol, diallyl disulfide and furaneol were the key odorants that maintain the spicy and meaty notes of beef flavoring during storage. Therefore, the addition of spices not only affected the types of volatile compounds, but also slowed down the decrease in the intensity of meaty note and the increase in burnt and soybean paste-like notes. This study can provide a theoretical basis for the development of high-quality thermal reaction-derived flavorings and a reference for the diversification of thermal reaction-derived flavorings.

The organic acids and amino acids of 88 samples of apricot seed kernels from southern Xinjiang were determined by gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC). The results showed that the content of total organic acids ranged from 23.75 to 11 446.19 μg/g, malic acid comprising the highest proportion (46.66%) of the total, followed by oxalic acid (14.67%) and citric acid (12.06%), and gluconic acid accounting for the lowest proportion (0.05%). Oleic acid was the predominant unsaturated fatty acid, accounting for 59.91% of the total fatty acids; and palmitic acid was the major saturated fatty acids, accounting for 12.57% of the total fatty acids. A total of 15 amino acids were detected in all samples, the total amino acid content was 79.55–4 464.17 μg/g, and the essential amino acid content was 21.62–1 248.35 μg/g. The results of principal component analysis (PCA) showed that the cumulative variance contribution rate of the first eight principal components for acid compounds was 85.05%, and malic acid, citric acid, valine, threonine, glutamine, serine, oleic acid, linoleic acid, succinic acid and acetic acid important indexes for evaluating the quality of apricot seed kernels. The samples were clustered into four groups based on the contents of 31 polar metabolites. The first group consisted of eight samples, which were abundant in malate, fatty acid and glutamate. The second group included 77 samples, which were moderate in malic acid and fatty acid and low in amino acids. The third group included ‘Zao Da You Xing’ and ‘Lopu 2’, which had high succinic acid content, moderate fatty acid content and low amino acid content. The final group included ‘Wan Shu Hei Ye Xing’, characterized by the highest succinic acid content, low fatty acid content and high amino acid content.

In order to investigate the influence of the refining process on the quality and sensory properties of snakehead fish oil, the physicochemical properties, fatty acid composition and volatile flavor composition during the refining process of crude fish oil extracted from snakehead viscera were evaluated. The results showed that the physicochemical properties of snakehead fish oil were significantly improved; the acid value, peroxide value, moisture content, volatile content, anisidine value and unsaponifiable matter content were significantly reduced, and the iodine value was increased. In total, 27 fatty acids were detected in snakehead fish oil, the major ones being oleic acid, linoleic acid, and palmitic acid. During the refining process, the number of fatty acids was almost unchanged, the contents of monounsaturated and polyunsaturated fatty acids increased, while a reverse trend was observed for the content of saturated fatty acids. Additionally, a total of 99 volatile compounds were detected during the refining process of snakehead fish oil, among which 14 compounds including 1-octen-3-ol, hexanal, nonanal, 2-heptenal, (E,Z)-2,6-nonadienal, 2,4-decadienal, and trans-2,4-decadienal were the key flavor substances of snakehead fish oil. These findings provide a theoretical basis and technical support for the deep processing and high-value utilization of snakehead fish visceral oil.

In this study, the amylose contents in 24 commercial foxtail millet samples from major production provinces in China were determined by four different methods, namely, the improved national standard method (GB/T 15683-2008), the spectrophotometric method (NY/T 2639-2014) recommended by China’s agricultural authority, the dual-wavelength method, and the concanavalin A (Con A) method. The results of these methods were in the following decreasing order: improved GB/T 15683-2008 ≈ dual-wavelength > NY/T 2639-2014 > Con A. The correlation coefficient between the results of improved GB/T 15683-2008 and those of NY/T 2639-2014 was highest, 0.752 (P = 0), the former being about 1.41 times higher than the latter, which could allow simple prediction of the amylose content of foxtail millet. In conclusion, the improved GB/T 15683-2008 method, the dual-wavelength method and the NY/T 2639-2014 (× 1.41) method can be used to accurately determine the content of amylose in foxtail millet while greatly reducing sample testing time.

In this study, the contents of total phenols and total anthocyanins in blue honeysuckle fruit from six regions (Jiagedaqi, Xinlin, Hongwei, Amur, Tuqiang and Tahe) of the Greater Khingan Mountains were determined and compared, the antioxidant capacity of phenols from blue honeysuckle fruit was comprehensively analyzed using three different methods, and the hypoglycemic activity was evaluated by measuring its half maximal inhibitory concentration (IC50) against α-amylase and α-glucosidase. The crude extract rich in polyphenols were separated and purified, and the resulting fractions were analyzed qualitatively and quantitatively. The results showed that the contents of total phenols and total anthocyanins in blue honeysuckle fruit from these six regions differed significantly, but the compositions were basically the same and all phenolic extracts had high antioxidant capacity. They had inhibitory activity against α-amylase and α-glucosidase, indicating the potential of blue honeysuckle fruit from these six regions for development and utilization.

Gas chromatography-ion mobility spectrometry (GC-IMS), gas chromatography-flame ionization detector (GC-FID), gas chromatography-mass spectrometry (GC-MS) and sensory evaluation were used to study the chemical flavor and sensory characteristics of sauce-flavor baijiu from four different origins in China. Totally 152 volatile compounds were identified, including esters, alcohols, ketones, and aldehydes. Through partial least squares discriminant analysis, 17 differential markers with variable importance in projection (VIP) value greater than 1 were selected from the 39 main volatile compounds to distinguish sauce-flavor baijiu from different origins. Sensory evaluation showed differences in the flavor characteristics of baijiu samples from the four origins which could be effectively identified by sensory evaluation and gas chromatography (GC). This study also clarified the material basis of the flavor difference, whose results provide a theoretical basis for the design of sauce-flavor baijiu body.

Lipid oxidation and degradation in instant meatballs stored for different periods of time (0, 1, 2, 3, 4 and 5 days) were investigated by measuring peroxide value (POV), thiobarbituric acid reactive substances (TBARS) value, carbonyl value and diene value. The changes in the fatty acid composition of instant meatballs during storage were analyzed by gas chromatography-mass spectrometry (GC-MS). The evolution of volatile flavor compounds was studied by headspace-solid phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) combined with calculation of odor activity value (OAV) and sensory evaluation. The results showed that eating quality attributes such as flavor and texture continued to decline during storage. Off-flavor appeared on the 4th day, and then quality deterioration was accelerated. The POV increased significantly during the early stage (0–3 days), but did not change significantly at the later stage (3–5 days). The TBARS value first increased slowly (0–4 days) and then dramatically (4–5 days). The carbonyl and diene values showed an upward trend during storage, indicating an increase in the degree of lipid oxidation. During storage, the proportion of unsaturated fatty acids (UFA) especially polyunsaturated fatty acids (PUFA) was significantly reduced. A total of 36 volatile flavor compounds with OAV ≥ 0.1 were detected. Among of them, the number (15) of aldehydes was highest. The OAVs of aldehydes and alcohols accounted for a high proportion (79.73%–87.58% and 10.15%–16.64%, respectively) of the total. Four and two classes of odor-active compounds were significantly correlated with lipid oxidation and sensory score for flavor, respectively.

The patterns of changes in the physicochemical properties and volatile flavors of abalone muscle during drying at 50 ℃ and 65% relative humidity were investigated in this study. With an increase in drying time, the browning intensity and fluorescence intensity of both surface and internal muscles of abalone increased gradually, which started to decrease after reaching a peak on the 90th day. The contents of reducing sugar and lysine in the surface muscle were 3.11 mg/g and 2.60% after pretreatment, and decreased to 1.95 mg/g and 1.61% after 120 days of drying, respectively. High molecular mass polymers were observed in the electrophoretic pattern of abalone muscle after 30 days of drying. Fourier transform infrared spectra showed that the intensity of the characteristic absorption peaks (1 403 and 1 026 cm-1) of glycoproteins gradually enhanced with increasing drying time. The response values of the electronic nose sensors W1W (sulfides) and W2S (alcohols, aldehydes and ketones) increased, and the content of 1-octen-3-ol decreased while the contents of linalool and (E,E)-2,4-decadienal increased after 30 days of drying, as determined by gas chromatography-mass spectrometry (GC-MS). At the same drying time, the intensity of Maillard reaction in the surface muscle was weaker than that in the internal muscle.

A gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM) method for the precise quantitative and qualitative analysis of 58 volatile components in grape fruits of different varieties using stable isotope labeled internal standard was developed based on the understanding of the mass spectrometric cleavage behavior of special volatile components. The difference in the volatile composition of the tested varieties was explored. After crushing and homogenization, grape samples were extracted by solid phase microextraction (SPME) and analyzed by GC-MS-SIM. The results indicated that this method had good linear relationships within the investigated concentration range with a correlation coefficient (R) greater than 0.995 0 for all analytes expect for isopropanol (equal to 0.967 1). The limits of detection (LODs) for most target compounds were lower than 1.56 μg/kg. The spiked recoveries of only a few volatile components were very low, while those of most volatile components ranged from 60.64% to 129.63% with relative standard deviations (RSDs) less than 19.56%. This method was suitable for qualitative and quantitative analysis of volatile components in grape and other fruits as well as vegetables, with high sensitivity and accuracy. Furthermore, the characteristic volatile components of 12 grape varieties were identified by analyzing the differences in their volatile composition.

In order to explore the characteristic flavor compounds and to infer the possible main flavor precursors in irradiated pigeon meat, the changes of volatile compounds and lipid metabolites in irradiated pigeon meat were analyzed by headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and ultra-high performance liquid chromatography-tandem quadrupole time-of-flight high-resolution tandem mass spectrometry (UPLC-Triple-TOF MS/MS). The results showed that hydrocarbon and aldehydes were the major volatile components in pigeon meat. There were 10 key flavor components identified, among which, nonanal, (E)-2-hexenal, decanal, hexanal, (E)-2-octenal, (E,E)-2,4-nonadienal, octanal, 2,4-decadienal, and 1-octen-3-ol substances were derived from lipid oxidation, and nonanal aldehydes such as aldehydes, decanal, and hexanal may be generated by the decomposition of oleic and linoleic acids. Fatty acids (FA), AcylCarnitine, plasmenylPE, GlcCer_NDS, AcyGlcADG, lysoPC, Cer_BS, and lysoPS were identified as significantly differential lipid subclasses. Among the 30 lipid molecules with variable importance in the projection (VIP) scores higher than two, 6 contained oleic acid (C18:1) and 10 contained linoleic acid (C18:2). Oleic acid and linoleic acid, precursors for the formation of the characteristic flavor substances of pigeon meat, may be generated by the degradation of these 16 lipid molecules.

The moisture distribution and key volatile flavor compounds of beef tallow from Qinchuan cattle roasted for different periods were analyzed by low field-nuclear magnetic resonance (LF-NMR) spectroscopy and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The results showed that the L* value significantly decreased (P < 0.05), the a* and b* values first increased and then decreased with roasting time. The proportion of bound water in beef tallow did not change significantly (P > 0.05), while the proportion of immobile water first increased and then decreased, and the proportion of free water showed an overall downward trend (P > 0.05). The relaxation time T23 and T24 showed a significant decreasing trend as roasting time increased (P < 0.05), indicating that the binding between water molecules and macromolecular substances such as protein and lipid became tighter. Beef tallow samples roasted for different periods could be effectively distinguished by electronic nose and the roasting process had a significant effect on the contents of alcohols, aromatic compounds, terpenes, and organic sulfur compounds in beef tallow according to principal component analysis (PCA) of the electronic nose data. A total of 95 volatile compounds were identified in all samples. The contents of 1-methoxy-2-propanol, 1-octene-3-ol, hexanal, nonanal, acetic acid, nonanoic acid, and acetamide were relatively higher in each sample, whereas ketones, heterocycles and amine compounds occurred mostly in the later stages of roasting. In total 19 key aroma components were identified based on odor activity value (OAV) and most of the substances have the largest OAV at 12 min of roasting.

Comparative analysis of aroma-active compounds in large-leaf yellow tea and rice crust was carried out via headspace solid phase micro-extraction (HS-SPME) combined with gas chromatography-olfactometry-mass spectrometry (GC-O-MS) to elucidate the material basis of the rice crust-like aroma of large-leaf yellow tea. The results revealed that 72 and 45 volatile compounds were identified in large-leaf yellow tea infusion and rice crust, respectively. In total, 15 aroma-active components were found in both large-leaf yellow tea and rice crust. Among them, five pyrazines responsible for a roasted aroma were common to both, which made a key contribution to the characteristic rice crust-like aroma of large-leaf yellow tea. 2-Ethyl-3,5-dimethylpyrazine, 2-ethyl-5-methylpyrazine and 2,6-diethylpyrazine were the key aroma-active components of both large-leaf yellow tea and rice crust. 3,5-Diethyl-2-methylpyrazine was key to the formation of the rice crust-like aroma of large-leaf yellow tea, but contributed little to the characteristic aroma of rice crust. 3-Ethyl-2,5-dimethylpyrazine was key to the formation of the characteristic aroma of rice crust, butt contributed little to the characteristic aroma of large-leaf yellow tea.

In order to explore the changes of volatile components in half-boiled and pan-fried potatoes at different processing stages, the volatile components and metabolites were determined by gas chromatography-mass spectrometry (GC-MS), gas chromatography-ion mobility spectrometry (GC-IMS) and widely targeted metabolomics. It was found that the color of potatoes changed from light yellow to golden yellow to brown yellow after being half-boiled and pan-fried. GC-MS analysis showed that the volatile components in raw potatoes mainly included alcohols, with a relative content of 91.85%, and the key flavor substances were octanal, nonanal, decanal, and 2-pentylfuran. The major volatile components in half-boiled potatoes were aldehydes and esters, with relative contents of 38.82% and 15.81%, respectively, and the key flavor substances were octanal, nonanal, decanal and 2-pentylfuran. The major volatile components in half-boiled and pan-fried potatoes were aldehydes and pyrazines, with relative contents of 57.40% and 28.76%, respectively, and the key flavor compounds were octanal, nonal, decal, 2-pentylfuran, trans-2,4-heptandienal, 2-ethyl-5 or 6-methylpyrazine, and 2-ethyl-3,6-dimethylpyrazine. A total of 36 volatile components were identified by GC-IMS, and the types of these volatile components were different from those identified by GC-MS, but the results of GC-MS and those of GC-IMS complemented to each other. By widely targeted metabolomic analysis, 22 kinds of metabolites, such as amino acids and their derivatives, carbohydrates, nucleotides and their derivatives, lipids and their derivatives, and flavonoids were identidied, among which 14 were identified as different metabolites with variable importance in the projection (VIP) > 1 at P < 0.05 in t-test, which were significantly correlated with volatile components. L-Asparagine, L-glutamic acid, acetamide, and phosphoric acid had a significant correlation with various volatile metabolites, and their contents were higher in the samples.

The objective of this study was to investigate the effects of natural fermentation and inoculated fermentations with Pichia pastoris and active dry wine yeast BV818 (Saccharomyces cerevisiae) on the flavor of yellow peach wine. Simultaneous inoculation, sequential inoculation of P. pastoris and BV818 with a time interval of one and three days, and inoculation of BV818 alone were used. Gas chromatography-mass spectrometry (GC-MS), gas chromatography-ion mobility spectrometry (GC-IMS) and quantitative descriptive sensory analysis were used to study the effects of different fermentation methods on volatile flavor substances in yellow peach wine. The results showed that for all groups, ethanol fermentation was completed within 15 days, and 31 and 22 compounds were detected by GC-MS and GC-IMS, respectively. In the sequential fermentation groups, the content of alcohols increased, the contents of acids and esters decreased, and the numbers of terpenes, alcohols and acids increased. In the sensory evaluation, the sequential fermentation groups had higher aroma richness and aroma balance than the other groups. The simultaneous fermentation group scored higher in sensory score for nutty and sweet aroma. The naturally fermented wine had the strongest sour aroma. In summary, mixed fermentation with P. pastoris and S. cerevisiae can improve the aroma of yellow peach wine, and the sensory score of the wine produced by sequential inoculation with a three-day interval was highest.

A methodology for the non-targeted detection of milk powder authenticity using Raman imaging was proposed in the present study. Meanwhile, a novel flow-based discrimination neural network was developed to extract the deep feature of the Raman image of milk powder. Using a combination of possibility distribution transformation and non-volume preserving strategies, feature distribution of authentic milk powder was constructed to distinguish between normal and adulterated milk powder samples. As a result, this method could identify various adulterated samples with an accuracy higher than 97.3%, and the limit of detection was 0.3%. The present methodology was characterized by a wide range of applicability, high precision, convenience and rapidity and could meet the demand of milk powder authenticity detection in practice, which may also provide a new approach for non-targeted detection of the authenticity of other non-homogenous food systems.

The housekeeping genes atpD, gyrB, infB, fusA and glnS in Cronobacter sakazakii were selected as target sequences to construct plasmid standards for rapidly detecting C. sakazakii. The constructed recombinant plasmids was verified by colony polymerase chain reaction (PCR) and sequencing and was checked for stability after 15 passages. The atpD, gyrB, infB, fusA and glnS plasmid standards were qualitatively tested and evaluated in terms of limit of detection (LOD) and stability. Then, these plasmid standards were used to detect C. sakazakii in infant milk powder. The results of colony PCR and sequencing showed successful construction of the atpD, gyrB, infB, fusA and glnS plasmid standards. The PCR system was specific for the detection of the plasmid standards. The detection limits of atpD, gyrB, infB, fusA and glnS were 1.14 × 106, 1.07 × 107, 1.09 × 107, 1.73 × 105 and 7.54 × 105 copies/μL, respectively. The lyophilized plasmids could be stored stably at −20, 4 and 25 ℃ for 90 days. The plasmid standards were used to detect 23 samples of infant milk powder, and one of them was detected positive for gyrB. However, C. sakazakii was undetectable by the traditional national standard method (GB 4789.40-2016). Compared with the traditional method, the application of the plasmid standards greatly improved the detection efficiency of samples.

Objective: To develop a method to quantitatively analyze the residues of six pesticides (carbendazim, tricyclozole, bensulfuron methyl, triazophos, chlorpyrifos and carbosulfan) in paddy and rice by quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and to propose a quantitative model for pesticide residues using Minitab software. Methods: Positive samples were prepared by spraying pesticide mixture solution on paddy and rice, and stored at constant temperature and relative humidity conditions simulating those in grain depot. Temperature and relative humidity as key variables were set at different levels, namely 20, 30, 40 and 50 ℃; and 50%, 60%, 70% and 80%. Results: The calibration curves for the six pesticides showed good linearity in the concentration range of 5.0–1 000.0 μg/L with correlation coefficient (R2) greater than 0.999 0, the detection limits were in the range of 0.000 1–0.005 mg/kg, the average spiked recoveries were in the range of 84.02%–103.24%, and the precision, expressed as relative standard deviation (RSD), was in the range of 3.65%–8.29%. Therefore, the QuEChERS-UPLC-MS/MS method can meet the requirements of the analysis and detection of pesticide residues. The quantitative model of pesticide degradation during the whole process from paddy to rice, developed by the processing factors investigated, showed R2 value above 0.769. Among them, the R2 values for carbendazim, bensulfuron, triazophos and chlorpyrifos in paddy were greater than 0.9, and those for triazophos and butachlor in rice were also greater than 0.9, indicating good fitness. The residues of the six pesticides in the positive samples gradually decreased with storage time, and the degradation rate of pesticide residues changed with storage environment. Conclusion: The QuEChERS-UPLC-MS/MS method is simple, rapid, and accurate and suitable for the detection of the six pesticide residues in paddy and rice. The quantitative model of pesticide degradation during the whole process from paddy to rice is well fitted, and the degradation patterns of pesticide residues in paddy and rice under different storage conditions are different. This study has important significance to improve the comprehensive benefits of the grain industry.

In order to judge the mildew degree of wheat seeds quickly and accurately, this study proposed a qualitative analysis method for moldy wheat using terahertz time-domain (THz-TDS) spectroscopy combined with support vector (SVM), random forest (RF) or extreme learning machine (ELM). According to the content of aflatoxin B1 (AFB1), wheat seeds were classified into four types: normal, slight mildew, moderate mildew and severe mildew. Spectral data in the band of 0.1–4.0 THz were obtained using a CCT-1800 THz spectrometer. The effects of different spectral pretreatment methods on the results discrimination were examined, and three dimensionality reduction methods, principal component analysis (PCA), linear discriminant analysis (LDA), and t-distributed stochastic neighbor embedding (t-SNE), were used to reduce the dimension of spectral data. LDA was found to be the best method. Finally, a model based on SVM, RF or ELM was constructed. The SVM model had the best classification effect. When polynomial kernel function was chosen and error penalty coefficient was 1, the accuracy of discrimination was 98.61% and the root mean square error of prediction was 0.142 9. This study confirms that THz spectroscopy can be applied for accurate detection of wheat mildew, which can provide a detection approach for food safety and grain storage and detection.

In order to protect the geographical origin information of Chinese chestnut as a geographical indication product, 164 Chinese chestnut samples were collected from 10 provinces, including Qianxi in Hebei, Jixian in Tianjin and Huairou in Beijing for analysis of stable isotopes (C, H, O, and N) and mineral elements using elemental analysis-stable isotope mass spectrometry and inductively coupled plasma mass spectrometry (ICP-MS). Analysis of variance (ANOVA), principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to classify the production regions of Chinese chestnut and establish a geographical origin traceability model. The results showed that the cross-validation rate of the OPLS-DA model for the 10 geographical origins was 100%, and the area of the receiver operating characteristic (ROC) curve was close to 1. The elements Mg, δ2H, δ18O, Al, Na, δ15N, Cu, Ba, Zn and Th were the main factors (variable importance in the projection, VIP > 1) to distinguish Hebei chestnuts and those from the other nine production regions. The established model can provide an effective theoretical basis for geographical origin discrimination of Chinese chestnut.

A new method for rapid screening for and identification of 11 foodborne stimulants and five alkaloids in hot pot soup base seasoning by ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF/MS) was developed. The analytes from samples were extracted with 80% aqueous acetonitrile, cleaned up on a PRiME HLB column, and separated on a Kinetex F5 column prior to qualitative screening and quantitative analysis in the high-resolution scanning mode using multiple reaction monitoring (MRM). The relative deviations of the exact mass numbers of the 16 compounds were less than 5.0 × 10-6, and the linearity of the calibration curves was good with correlation coefficient (R2) greater than 0.997 0. The recoveries of the analytes were 75.2%–105.4%, with relative standard deviation (RSD) of 1.3%–7.4% (n = 6). The limit of detection (LOD) was 0.05–1.0 μg/kg, and the limit of quantitation (LOQ) was 0.10–2.0 μg/kg. The developed method is simple, rapid, accurate, and practical.

A method was developed for the simultaneous screening and determination of eleven mycotoxins in tomato by ultra-high performance liquid chromatography-quadrepole/orbitrap high-resolution mass spectrometry (UPLC-Q/Orbitrap HRMS). Samples were extracted with a mixture of 1% formic acid solution and acetonitrile (99:1, V/V), salted out using a QuEChERS (quick, easy, cheap, effective, rugged and safe) extraction packet, and purified by dispersive solid phase extraction (dSPE). The target compounds were separated on an ACQUITY UPLC BEH shield RP18 column (100 mm × 2.1 mm, 1.7 μm), detected using an electrospray ionization source under positive and negative ion scanning with parallel reaction monitoring. A tandem mass spectral library for rapid screening of the eleven mycotoxins was built based on characteristic fragment ions. The results showed a good linear relationship in the concentration range of 0.25–100.0 mg/L, with correlation coefficients (R2) more than 0.991. The limit of detection (LOD) ranged from 0.1 to 10.0 μg/kg, and the limit of quantification (LOQ) ranged from 0.3 to 30.0 μg/kg. Average recoveries at three spiked levels, LOQ, 2 × LOQ, and 10 × LOQ, were in the range of 78.5%–108.7% with relative standard deviations from 1.0% to 9.3% (n = 6). This method proved to be simple, sensitive, accurate, and suitable for rapid screening and accurate quantification of the eleven mycotoxins in tomato.

A core-shell-satellite nanostructure surface-enhanced Raman scattering (SERS) substrate based on magnetic nanoparticles, metal-organic frameworks (MOFs) and gold nanoparticles (Ag NPs) was established and applied in the simple, rapid and sensitive detection of the organophosphorus pesticide triazophos in agricultural products. MIL-100(Fe)-coated Fe3O4 was prepared by low-temperature cyclic self-assembly method, and Ag NPs were in-situ grown on the surface of MIL-100(Fe)-coated Fe3O4 by silver mirror cycling. The SERS sensing of triazophos residues in apples was carried out. The logarithmic value (Y) of the characteristic peak intensity of triazophos was linearly related to the logarithmic value (X) of its concentration in the range of 0.05–10 mg/L, which was described by the following equation: Y = 0.573 8X + 2.804 (R2 = 0.980). The limit of detection (LOD) was as low as 11.9 mg/L. The recoveries of the developed method ranged from 90.07% to 103.27% at spiked concentrations of 2, 5, and 10 mg/L. Therefore, the prepared SERS substrate has great potential for application in the detection of pesticide residues in foods.