To clarify the residue and dissipation dynamics of 22% thiamethoxam•lambda-cyhalothrin microcapsule suspension-suspension concentrate in Glycine max L. Merr.

This paper conducted field trials in accordance with the reference to the NY/T 788—2018 Guidelines for the testing of pesticide residues in agricultural crops, and the residues and dissipation dynamics of in Glycine max L. Merr at different application doses by means of QuEChERS-liquid chromatography-tandem mass spectrometry (QuEChERS-LC-MS/MS) and QuEChERS-gas chromatography-tandem mass spectrometry (QuEChERS-GC-MS/MS).

Within the mass concentration ranges of 0.002–0.050 μg/mL and 0.005–0.500 μg/mL, thiamethoxam and lambda-cyhalothrin exhibited an excllent linear relationship between mass concentration and response values in Glycine max L. Merr matrices, and the correlation coefficients exceeded 0.99. In the recovery experiment, the average recovery rate for thiamethoxam was 79.9%–92.4% with the relative standard deviations 0.46%–8.71%, while that for lambda-cyhalothrin was 84.50%–97.10% with the relative standard deviations 0.39%–9.11%. According to the first-order kinetic equation fitting, the half-lives of thiamethoxam and lambda-cyhalothrin in Glycine max L. Merr during the degradation process were both less than 15 d, classifying them as readily degradable pesticides. At the recommended dosage and 2 times the recommended dosage, the half-lives of thiamethoxam were 10.7 d and 4.3 d, respectively; while for lambda-cyhalothrin, the half-lives were 3.3 d and 7.3 d, respectively. The residue dynamics of thiamethoxam and lambda-cyhalothrin at the recommended dosage showed an initial increase followed by a decrease, reaching peak levels 5 d after application before gradually degrading.After 14 days of application, at the recommended dose and 2 times the recommended dose, the residues of both thiamethoxam and lambda-cyhalothrin exceeded the maximum residue limit (MRL), posing a risk of pesticide overlimit.

In open-field Glycine max L. Merr production, 22% thiamethoxam•lambda-cyhalothrin microcapsule suspension-suspension concentrate should be strictly applied at the recommended dosage. It is advised to rigorously implement a safety interval of over 16 d or more and prohibit excessive dosage application.

To prepare non-starch polysaccharides from Yangshan Dioscorea opposita Thunb. by ultrasonic-assisted water extraction, and investigate their antioxidant activities.

Hot-water extraction and ultrasonic-assisted hot-water extraction combined with glucoamylase were adopted to obtain Dioscorea opposita Thunb.non-starch polysaccharides, designated as CYP-H and CYP-U, respectively. The content of total sugar, uronic acid and protein of the 2 kinds of polysaccharides were determined by chemical assays. Size-exclusion chromatography coupled with multi-angle laser light scattering, Fourier-transform infrared spectroscopy and ion chromatography were used to characterize their structural features including molecular-weight distribution, infrared absorption and monosaccharide composition. The antioxidant activities of the 2 kinds of polysaccharides were compared via multiple chemical models including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, hydroxyl radical, 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) cation radical and Fe³⁺ reduction assay, as well as the zebrafish oxidative-stress model induced by 2,2’-azobis(2-amidinopropane) dihydrochloride (AAPH).

The yields of CYP-H and CYP-U were 17.72% and 19.53%, respectively, with the total sugar, uronic acid and protein content of 77.56%, 19.51%, 2.29%, and 82.56%, 20.67%, 4.46%, respectively. Their weight-average molecular weights were 5.263 kDa and 6.645 kDa, respectively, and both exhibited typical infrared absorption spectra characteristics of polysaccharides. Ion chromatography analysis revealed that both CYP-H and CYP-U contained arabinose, galactose, glucose and mannose. The molar ratios were 1.0:6.8:93.5:11.1 for CYP-H and 1.0:4.8:185.2:13.1 for CYP-U. These results demonstrated the differences in the chemical composition and molecular structural characteristics of the 2 kinds of non-starch polysaccharides. Moreover, within the range of 2–10 mg/mL, both polysaccharides exhibited scavenging activity against DPPH radicals, hydroxyl radicals and ABTS⁺ radicals, as well as Fe³⁺ reduction capacity. However, CYP-H and CYP-U exhibited differences in their ability to scavenge different free radicals. Moreover, both CYP-H and CYP-U reduced reactive oxygen species (ROS) and malondialdehyde (MDA)levels while enhancing superoxide dismutase (SOD) activities in the AAPH-induced oxidative stress zebrafish model, with CYP-U demonstrating superior efficacy compared to CYP-H and exhibiting a favorable dose-response relationship.

Ultrasonic assistance enhances the yield of non-starch polysaccharides from Yangjiang Dioscorea opposita Thunb. and modestly increases their antioxidant activity in vivo. These findings provide scientific support for the applications of Yangjiang Dioscorea opposita Thunb. in functional foods with antioxidant potential.

To investigate the mechanism by which myoglobin deteriorates the gelation properties of myofibrillar protein during the processing of unwashed surimi products.

The effects of different rinsing cycles on the gel properties of Hypophthalmichthys molitrix surimi were analyzed to confirm that unwashed surimi contains a higher level of myoglobin and exhibits poorer gel performance. A myoglobin‑myofibrillar protein mixed system was then constructed. Changes in hydrophobic interactions, hydrogen bonds and ionic bonds between proteins were measured, and water distribution was analyzed using low‑field nuclear magnetic resonance.

After 0 h of reaction with 86 μmol/L myoglobin, hydrophobic interactions, hydrogen bonds and ionic bonds decreased by 14.02%, 19.86% and 23.24%, respectively, and the proportion of immobilized water (T₂₃) peak area decreased by 3.84%. After 24 h of reaction, the deterioration intensified: all intermolecular forces further decreased compared with those at 0 h, and the T₂₃ peak area proportion dropped to 87.90%, a decrease of 4.17% compared with the blank control group (0 μmol/L myoglobin) at the same time point. The gel network changed from dense and uniform to rough and loose, resulting in significantly reduced water‑holding capacity and increased cooking loss.

Myoglobin interferes with molecular cross‑linking between surimi proteins through steric hindrance, weakens intermolecular forces, disrupts the gel network structure, and consequently induces water migration and loss. This research has clarified the action path and influence rule of myoglobin on myofibrillar protein gel network, which can provide theoretical basis for improving the quality of gel by regulating endogenous heme protein during the processing of unwashed surimi gel.

To optimize the formula and develop a composite solid beverage with both functional and eating qualities, utilizing Sesamum indicum L., Glycine max (L.) Merr. and collagen peptide as the main raw materials, supplemented by maltodextrin, inulin, sucrose and sodium alginate.

The solid beverage of Sesamum indicum L.-Glycine max (L.) Merr.-collagen peptide was evaluated based on sensory scores and reconstitution properties.Single-factor experiments and orthogonal experiments were conducted to optimize the formula for the addition amounts of Sesamum indicum L., Glycine max (L.) Merr. and collagen peptide. The main nutritional components and active ingredients of the obtained product were evaluated, and the in vitro antioxidant activities and the powder properties of the product were also evaluated.

The optimal formula for the composite solid beverage was determined as follows: Sesamum indicum L. 25.0%, Glycine max (L.) Merr. 15.0%, collagen peptide 6.0%, maltodextrin 42.7%, inulin 10.0%, sucrose 1.0% and sodium alginate 0.3%. Under this formula, the product exhibited a uniform and fine texture, a mellow and smooth taste, and achieved the highest sensory score. Its protein and fat content were 17.7% and 17.1%, respectively. The content of total phenolics, melanin and anthocyanins were 13.10 mg GAE/g, 10.02 mg SME/g and 0.15 mg CGE/g, respectively, demonstrating certain antioxidant activities. The powder characteristic analysis results indicated that it possessed good reconstitution-dispersibility and flowability.

This study successfully develops a Sesamum indicum L.-Glycine max (L.) Merr.-collagen peptide solid beverage with excellent sensory quality, rich nutrition and antioxidant function, providing a theoretical basis and technical support for the development and industrial application of deep-processed Sesamum indicum L. and Glycine max (L.) Merr. products.

To investigate the differences in characteristic components of Lentinula edodes based on different drying methods, and identify unique compositional markers.

This study took the main cultivated strain 939 of Lentinula edodes from Xixia County, Nanyang City, Henan Province as the research object. Ultra performance liquid chromatography-triple quadrupole/linear ion trap mass spectrometry was employed to determine the content differences of bioactive substances (e.g., ergosterol), organic acids (e.g., succinic acid) and free amino acids(e.g., aspartic acid). Combined with multivariate statistical data analysis, the variations in characteristic components of Lentinula edodes subjected to different drying methods were systematically investigated.

Compared with other drying methods, the total content of bioactive components such as ergosterol in Lentinula edodes was higher after vacuum freeze-drying and microwave vacuum freeze-drying; the total content of organic acids such as succinic acid reached the highest level after microwave vacuum freeze-drying; and the total content of free amino acids was the highest after vacuum freeze-drying. Orthogonal partial least squares discriminant analysis (OPLS-DA) was applied to analyze the metabolite profiles under the 5 kinds of drying methods. Based on OPLS-DA, the criteria of P<0.05, variable importance in projection (VIP)>1, and fold change (FC)>2 or FC<0.5, a total of 7 differential compounds were identified, namely succinic acid, glutamic acid, aspartic acid, citric acid, malic acid, arginine and proline, which could clearly discriminate Lentinula edodes subjected to different drying treatments.

In this study, targeted metabolomics is employed to compare the content differences of characteristic components in Lentinula edodes under various drying methods, thereby providing data support for the optimization of drying processes and the high‑value utilization of Lentinula edodes in processing.

To explore the differential marker metabolites of Lycium barbarum L. from different origins by non-targeted metabolomics technology.

Taking the geographical indication protected products of Lycium barbarum L. from different origins in Gansu Province as the research objects, non-targeted metabolomics analysis was conducted on Lycium barbarum L. samples collected from Jingyuan County and Minqin County in Gansu Province using high performance liquid chromatography-orbittrap quadrupole electrostatic field high resolution mass spectrometry (HPLC-Q-Orbitrap HRMS). Principal component analysis and orthogonal partial least squares-discriminant analysis were adopted to analyze the differential metabolites of 2 kinds of Lycium barbarum L.from different origins.

A total of 102 differential metabolites were identified between Jingyuan and Minqin Lycium barbarum L.. Taking Minqin Lycium barbarum L. as the control, 39 kinds of metabolites were significantly up-regulated and 63 kinds of metabolites were significantly down-regulated in Jingyuan Lycium barbarum L.. The differential metabolites were mainly flavonoids, followed by phenolic acids and their derivatives, amino acids and their derivatives, etc. Ergometrine, histaminol and dehydro-β-ionone, etc. were differential characteristic compounds. Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis indicated that the differential metabolites were primarily enriched in metabolic pathways such as flavonoid biosynthesis, flavone and flavonol biosynthesis, phenylpropanoid biosynthesis, one-carbon pool by folate, alanine, aspartate and glutamate metabolism.

The research results successfully screens out the differential metabolites of Lycium barbarum L. from 2 kinds of different producing areas and clarified the core differences in metabolic composition among Lycium barbarum L. from each producing area.Meanwhile, the characteristic marker metabolites that can be used to distinguish Lycium barbarum L. from the 2 kinds of different producing areas are identified, which provide characteristic indicators and scientific and reliable technical support for the origin identification and quality differentiation of Lycium barbarum L. from different producing areas.

To realize the rapid detection of toxin-producing Aspergillus carbonarius, and to establish a dual fluorescence quantitative polymerase chain reaction (qPCR) method for detecting the polyketide synthases(PKS) gene and nonribosomal peptide synthetase (NRPS) gene of Aspergillus carbonarius.

Taking the relatively conserved gene fragments of PKS and NRPS from toxin-producing Aspergillus carbonarius as targets,specific primer-probe sets were designed and screened respectively. After optimizing the reaction conditions of dual qPCR, the standard curve of the assay was established. Subsequently, the specificity, sensitivity, and repeatability of this method were verified. Finally, this method was used to test 80 actual samples and corn, peanut and soybean samples artificially inoculated with different concentrations of toxin-producing Aspergillus carbonarius spores.

The specificity test results demonstrated that this dual qPCR assay exhibited no non-specific amplification with common toxin-producing fungi such as Aspergillus flavus and Aspergillus parasiticus, but specifically amplified the PKS and NRPS genes of toxin-producing Aspergillus carbonarius. The sensitivity assay showed that the limit of detection of this method could reach 1×10² copies/μL. And the method presented excellent repeatability, with the intra- and inter-batch coefficients of variation both less than 1%. In the simulated sample test, this dual qPCR could detect spores at a minimum concentration of 1×10³ spores/mL in all 3 kinds of artificially infected samples.

The established dual fluorescence quantitative PCR has high sensitivity and accuracy, it can provide technical support for the early monitoring and control of ochratoxin A-toxin-producing Aspergillus carbonarius.

To establish an analytical method for the rapid detection of matrine pesticide residues in Fragaria ananassa Duch by colloidal gold immunochromatography.

By optimizing the labeling parameters of gold nanoparticles and the concentration of the test strip detection line, colloidal gold could bind with monoclonal antibodies against matrine under optimal conditions. By utilizing highly specific recognition of antibodies and antigens and visualization of gold labeled antibodies, the localization detection of matrine pesticide residues in Fragaria ananassa Duch could be achieved.

Determine the labeling parameters as follows: 1 mL of colloidal gold solution with 20 μL of 0.1 mol/L K₂CO₃, 8 μg of antibody, 5% polyvinyl pyrrolidone (PVP) surfactant,and an antigen transmembrane concentration of 0.10 mg/mL; using the above conditions, the limit of detection of matrine in Fragaria ananassa Duch samples was set to 10 μg/kg, and rapid detection was performed on 126 collected Fragaria ananassa Duch samples.

This method has high sensitivity and specificity, and can quickly and accurately detect residual matrine in samples, enabling rapid screening of a large number of samples on site.

To establish a method for the determination of 5 kinds of nucleotides in aquatic products by high performance liquid chromatography.

After optimization of chromatographic conditions and selection of pretreatment conditions, the sample was extracted twice with 5% perchloric acid solution at 4 ℃, and then extracted with 0.01 mol/L KH₂PO₄ (containing 1.45 mmol/L tetrabutyl ammonium bisulfate,pH=5.0)-acetonitrile (95:5, V:V) was eluted by mobile phase, separated by C₁₈ (250 mm×4.6 mm×5 μm) column,detected by ultraviolet detector, and quantified by external standard method with standard curve.

The 5 kinds of nucleotides had a good linear relationship in the range of 0.1–100.0 μg/mL, and the correlation coefficient was greater than 0.999. The limits of detection and limits of quantitation were 1.0–2.0 mg/kg and 3.0–6.0 mg/kg,respectively, and the precisions were 2.00%–6.87%. The spike recoveries were 92.3%–105.6%, the intra-assay standard deviations were 0.63%–7.90%, and the inter-assay standard deviations were 1.72%–7.34%.

This method has high sensitivity and good repeatability, and can be used for the qualitative and quantitative analysis of 5 kinds of nucleotides in aquatic products.

To conduct a comprehensive biological characterization of an oxacillin-susceptible mecA-positive Staphylococcus aureus (OS-MRSA) strain isolated from a retail chicken sample, assess its virulence potential and molecular typing characteristics.

Staphylococcus aureus strain SAC10 was isolated from supermarket frozen whole-chicken samples. Identification was performed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and antibiotic resistance profiles and the mecA gene were detected by antibiotic susceptibility testing and polymerase chain reaction (PCR). Whole-genome sequencing analyzed resistance genes, virulence genes and molecular typing. Virulence phenotypes were assessed via hemolysis assays, biofilm formation assays, and Galleria mellonella infection models. Sequence alignment elucidated the regulatory mechanism of the mecA gene.

SAC10 was identified as ST59-t437-IVa(2B) OS-MRSA. It carried mecA but exhibited phenotypic susceptibility, with its resistance gene profile consistent with the antimicrobial susceptibility pattern. The genome harbored multiple virulence factors (hlgABC, seb, sek, seq, aur, sak, scn),demonstrating strong hemolytic activity and biofilm-forming capability. Galleria mellonella assays revealed moderate virulence (16.67% survival at 72 h). Insertion of ISSau3 into the upstream promoter region of mecA suppressed its expression, resulting in the susceptible phenotype.

As a foodborne OS-MRSA, SAC10 combines virulence with concealed resistance genes, posing potential health risks via the food chain. The insertion mutation in mecA causing genotype-phenotype discordance highlights the need to combine conventional susceptibility testing with molecular detection to prevent underdiagnosis. These findings provide a scientific basis for improved monitoring and risk assessment of foodborne OS-MRSA.