Objective To evaluate the levels of metal elements contamination in Morella ruba Lour. from different production areas in Wenzhou and establish a comprehensive evaluation system. Methods The 121 Morella ruba Lour. samples and 68 soil samples from Morella ruba Lour. planting sites in Wenzhou were studied. The pH of the soil and 6 kinds of metal elements indicators, including chromium, nickel, arsenic, cadmium, mercury and lead, in both the soil and fruits were measured and analyzed. A fruit-soil correlation model (incorporating correlation analysis and principal component analysis of 13 parameters across 54 samples) was established. Results The qualification rate of Morella ruba Lour. samples was 94.21%, while the qualification rate of soil samples was only 39.71%; there was a varying degree of correlation between the metal elements content in Morella ruba Lour. fruits and soil, with a strong positive correlation between mercury in Morella ruba Lour. fruits and chromium and nickel in soil; principal component analysis identified chromium and cadmium in soil, as well as nickel, lead and arsenic in Morella ruba Lour., as the core indicators for evaluating the metal elements quality and safety of Morella ruba Lour.. Conclusion This study established a comprehensive evaluation system for metal elements quality safety in Morella ruba Lour., providing methodological references for regional agricultural product safety regulation.

Objective To prepare edible gelatin-corn starch bio-based composite film loaded with lactive Lactiplantibacillus plantarum CXG9, and endow the film with antibacterial activity and excellent film properties. Methods Using gelatin and corn starch mixed film as substrate, the bacterial mud obtained by Lactiplantibacillus plantarum CXG9 centrifugation was mixed into gelatin-corn starch mixture, and the living bacteria edible composite film was prepared by solution casting method. By measuring the characterization of the film and its antibacterial activity in vitro, the effects of Lactiplantibacillus plantarum CXG9 on the properties of gelatin-corn starch film were studied. Results The elongation at break of the gelatin-corn starch composite film loaded with Lactiplantibacillus plantarum CXG9 increased by 35.51%, the moisture content decreased by 2.55%, and the water vapor permeability also decreased by 11.2%. This indicated that the ultraviolet barrier ability, water vapor permeability, elongation at break, and thermal stability of the film loaded with Lactiplantibacillus plantarum CXG9 had all been improved. On the other hand, the addition of live bacteria gave the film antibacterial properties, and it had different degrees of inhibition on Listeria monocytogenes, Shigella, Escherichia coli, Staphylococcus aureus, Salmonella typhimurium and Pseudomonas aeruginosa. Conclusion In this study, gelatin-CXG9-corn starch antibacterial film loaded with Lactiplantibacillus plantarum CXG9 is successfully prepared by using gelatin-corn starch as substrate, which reduces the burden of traditional packaging materials on the environment and opens up a new way for the development of food packaging field.

Objective To screen salt-tolerant esterase-producing strains from yellow water and analyze their metabolic products. Methods Esterase-producing strains were isolated from yellow water and identified using morphological, physiological, biochemical and molecular biological methods. Results The 9 esterase-producing strains were screened from yellow water, among which CZ-1, CZ-5 and CZ-8 were Paenibacillus dendritiformis, CZ-9 was Paenibacillus cookii, CZ-10, CZ-13 and CZ-15 were Bacillus velezensis, and CZ-3 was Saccharomyces cerevisiae, P5-5 was Pichia manshurica. All 9 strains had good salt tolerance and could grow at pH 2.0-11.0, and 7 strains had salt tolerance up to 120 g/L. Experiments showed that when using caproic acid as the substrate, the esterifying enzyme activities of strains CZ-1, CZ-3, CZ-5, CZ-8, CZ-9, CZ-13, CZ-15 and P5-5 were 69.93, 70.62, 6.01, 67.65, 35.31, 48.51, 69.24 and 71.45 U/mL respectively, and strain CZ-10 had no esterifying enzyme activity. Gas chromatography-mass spectrometer analysis showed that 12 kinds of volatile components of alcohols, 7 kinds of volatile components of aldehydes, 1 kind of volatile component of ethers, 3 kinds of volatile components of amines, 11 kinds of volatile components of ketones, 9 kinds of volatile components of esters, 3 kinds of volatile components of acids and 22 kinds of other volatile components were detected in the fermentation broth. Conclusion The 9 esterifying enzyme-producing strains are screened from yellow water, all of which have good salt and alkali tolerance and esterifying enzyme activity. P5-5 has the highest esterifying enzyme activity and the most types of volatile components, which provides a theoretical basis for the subsequent treatment and application of yellow water.

Objective To evaluate the toxicological safety of xylooligosaccharides. Methods According to the national food safety standards, the safety of xylooligosaccharides was evaluated through acute oral toxicity test in mice, micronucleus tests in mammalian bone marrow red blood cells, chromosomal aberration tests in spermatocytes, Bacterial reverse mutation (Ames) test, and 28 day oral toxicity test. Results The acute maximum tolerated dose (MTD) of xylooligosaccharides in male and female mice was greater than 10000 mg/(kg·bw), which was classified as practically non-toxic; the micronucleus test of mammalian bone marrow red blood cells, chromosome aberration test of spermatocytes, and Ames test were all negative; set up 3 dose groups: 0 (basic feed control), 4167, 8333 and 16667 mg/(kg·bw) (equivalent to 25 times, 50 times and 100 times the maximum recommended intake), orally administered once a day for 28 consecutive days. The high-dose group of animals showed a decrease in total weight gain related to the test sample, changes in biochemical indicators such as alanine aminotransferase, alkaline phosphatase, glucose and urea nitrogen, and a decrease in organ weight and visceral to body ratio in male rats. However, there were no corresponding changes observed in the medium and low-dose groups (equivalent to 50 times and 25 times the maximum recommended intake) and the Weixing group. Conclusion Xylooligosaccharides do not show acute toxicity or genetic toxicity; the no observed adverse effect level (NOAEL) of the sample for 28 days of oral toxicity in female and male rats is 8333 mg/(kg·bw).

Objective To establish an analytical method for the determination of enrofloxacin residues in complex mixed matrix of the “soil-vegetable” system by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Methods The sample was subjected to vortex ultrasonic extraction with acidified acetonitrile extract [containing 5% ethylene diamine tetraacetic acid (EDTA)-Mcllvaine buffer solution], settling with centrifugation, getting solvent conversion and being filtered by 0.22 μm nylon filter membrane. The mobile phase was composed of acetonitrile and 0.1% formic acid aqueous solution (containing 2 mmol/L ammonium acetate), and the mixture was subjected to Waters ACQUITY UPLC ® BEH C₁₈ chromatographic column (2.1 mm×100 mm, 1.7 μm) gradient elution separation, using mass spectrometry as a detector for qualitative and quantitative analysis of enrofloxacin. Results In the mass concentration range of 1-200 ng/mL, the standard curve showed a good linear relationship (correlation coefficient=0.9996), the limit of detection of the method was 0.11 μg/kg, the recovery rates ranged from 87.4% to 103.3%, and the relative standard deviations (RSDs) were 0.4% to 4.0% (n=6). Conclusion This method has fast analysis speed, high accuracy and good repeatability, and is suitable for the detection of enrofloxacin residues in complex mixed matrix of the “soil-vegetable” system. It also has the potential to indirectly reveal the risk of antibiotic resistance genes (ARGs) contamination in the system.

Objective To establish a method for the detection of furosine in milk by microwave hydrolysis-ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Methods The optimal conditions for microwave hydrolysis were optimized by single factor experiments and response surface methodology. The hydrolysis solution obtained under the optimal hydrolysis conditions was filtered to a constant volume. The hydrolysate was diluted 10-fold with 6.0 g/L ammonium acetate solution and then analyzed. Gradient elution was performed with 0.1% formic acid aqueous solution and methanol solution as mobile phases, and the separation was carried out on a T3 liquid chromatography column (100 mm×2.1 mm, 1.8 μm). Under the positive ion mode of electrospray ion source (ESI⁺), multiple reaction monitoring (MRM) mode was selected for detection and external standard method was used for quantification. Results The optimal microwave hydrolysis conditions for furosine in milk were hydrolysis temperature of 160 ℃, hydrochloric acid concentration of 8.1 mol/L, and hydrolysis time of 52 min. The primary-to-secondary order of influencing factors was hydrochloric acid concentration>hydrolysis time>hydrolysis temperature. Furosine in milk showed a good linear relationship within the range of 0.005-0.500 µg/mL, with a correlation coefficient (r) of 0.9958. The limit of quantitation (LOQ) and limit of detection (LOD) were 0.20 µg/mL and 0.07 µg/mL, respectively. The average recoveries were 89.09%-97.33%, with relative standard deviations (RSDs) of 3.37%-7.02% (n=6). Conclusion This method is efficient and accurate. Compared with the traditional hydrolysis methods(12-24 hours), microwave hydrolysis shortens the hydrolysis time to 52 minutes, and there is no significant difference (P>0.05) in the detection results compared with the conventional hydrolysis methods in the industry standard NY/T 939—2016 Identification of reconstituted milk in pasteurized and UHT milk. It can provide technical reference for quality control and heat treatment process evaluation of dairy products.

Objective To rapidly identify the chemical components in the peel of Wogam by ultra performance liquid chromatography-tandem quadrupole electrostatic field orbital trap mass spectrometry (UPLC-QE-MS) in combination with various data analysis methods. Methods The samples were separated by Thermo Scientific Hypersil GOLD AQ (2.1 mm×100 mm, 1.9 μm) chromatographic column using solution A (0.1% formic acid-acetonitrile) and solution B (0.1% formic acid-water) as the mobile phase in a gradient elution mode. In the positive and negative ion mode, the electrical spray ion source was used to collect the signals of various chemical components in the peel of Wogam by means of one-step full scanning and two-stage ion scanning. Based on the high-resolution mass spectrometry data of traditional Chinese medicine components in the Trace Finder software and the screening network database of Compound Discoverer 3.2 software, the identification of chemical components were carried out by comparing the recognition of primary ions, major secondary ions, and other factors of the sample, as well as combining the possible cleavage pathways of the compound and consulting relevant literature reports. Through comprehensive analysis and judgment, the components were determined. Results Through literature review and comparison with high-resolution mass spectrometry data and databases, as well as compound analysis, a total of 52 compounds belonging to 11 categories were identified from the peel of Wogam, including 1 aldehyde, 5 organic acids, 2 alkaloids, 5 terpenes, 1 ketone, 7 phenylpropanoids, 2 coumarins, 1 nucleoside, 26 flavonoids, 1 anthraquinone, and 1 lignan. Conclusion The application of UPLC-QE-MS technology, combined with relevant databases and literature, enables the analysis of the chemical components of the peel of Wogam, providing a basis for the industrial development of Wogam peel.

Objective To optimize the protein extraction process of Pectinidae. Methods A combination of composite enzymes and segmented enzymatic hydrolysis was employed, utilizing different protease enzymes with mode of enzyme digestion and cleavage sites. Significant factors were screened by single factor combined with Plackett-Burman and Box-Behnken model was used to optimize the one-stage protein extraction process, and the parameters of the two-stage enzymatic digestion process were optimized by orthogonal tests. Results The optimal extraction conditions for complex enzyme-assisted stepwise hydrolysis in protein extraction were as follows: The optimal extraction process parameters of the one-stage were as follows, solid-liquid ratio was 1:3.9 (m:V), enzyme digestion time was 80.0 min, compound enzyme addition was 1.1%, complex enzyme ratio (trypsin:alkaline protease) was 1:2 (m:m), enzyme digestion pH was 8.2, enzyme digestion temperature was 52.5 ℃; the optimal extraction parameters of the two-stage were as follows: Enzyme digestion pH was 7.0, enzyme digestion temperature was 50.0 ℃, neutral protease addition was 0.8%, and enzyme digestion time was 40 min. Under these conditions, the protein extraction rate was 76.3%. Conclusion Due to synergistic and complementary effects between the complex enzymes and segmented enzymatic hydrolysis, the protein extraction rate of Pectinidae is effectively improved, which provide some theoretical basis for the subsequent development and utilization of proteins from Pectinidae.

Agricultural product safety form the foundation of constructing food supply systems. Smart hydrogels exhibit promising application prospects in agricultural safety analysis due to their stimuli responsiveness, mechanical stability, biocompatibility, and adjustable pore size. This review focused on the classification, preparation methods, responsive mechanisms and applications of smart hydrogels in agricultural product safety. Based on synthesis methods, they could be divided into physically cross-linked and chemically cross-linked hydrogels, while stimulus-responsive types included temperature-responsive, pH-responsive, biomolecule-responsive, electric field-responsive and magnetic field-responsive hydrogels. This study summarized their applications in contaminants adsorption/separation, foodborne pathogen detection, mycotoxin detection, pesticide/veterinary drug residue analysis, illegal additive identification, and heavy metal detection for agricultural product assurance. Development prospects of smart hydrogels are further discussed to provide references for their expanded utilization in agricultural product safety.

Objective To establish a method for the determination of 8 kinds of benzodiazepines residues, including diazepam, oxazepam, midazolam, clonazepam, lorazepam, triazolam, alprazolam and nitrazepam in aquatic products by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Methods The sample was extracted by 80% acetonitrile aqueous solution containing 0.2% formic acid, purified by Waters PRIME HLB solid phase extraction column, concentrated by nitrogen blowing in water bath. The residue contents were separated by C₁₈ chromatographic column, eluted by 0.1% formic acid aqueous solution-methanol mobile phase systems, and analyzed by electrospray ion source in positive ion multi-reaction monitoring mode. The quantitative information was obtained by matrix-added calibration with external standard. Results The correlation coefficient of calibration curves of 8 kinds of benzodiazepines residues were above 0.999. The limits of detection were 0.064-0.226 μg/kg, the recovery rates of the method were 70.4%-107.0%, and the relative standard deviations were 2.1%-10.2%. Conclusion The method is rapid, simple and accurate, and it is suitable for the determination of benzodiazepine sedative drug residues in aquatic products.