Objective To establish a method for the determination of 2-hexylpyridine content in the milk and dairy product by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Methods The sample was extracted by acetonitrile vortex extraction, and the analytical solution was purified by QuEChERS dSPE EMR Lipid degreasing tube. After centrifugation, it was tested on a membrane machine. The acetonitrile primary water as the mobile phase was used, the flow rate was set at 0.25 mL/min, the gradient elution procedure was applied, the GL Sciences InertSustain C₁₈ chromatographic column was used for separation, the electro spray positive ion (ESI⁺) mode, the multiple reaction monitoring (MRM) mode was used for detection, and the matrix matching external standard method was used for quantification. Results The methodological validation indicators were well that the calibration curves were linear in the range of 0.5-20.0 ng/mL with the correlation coefficients (r²) larger than 0.998. The average recoveries of 2-hexylpyridine were 94.45%-109.63% and the relative standard deviations were 3.93%-9.53% at 0.005, 0.010 and 0.050 mg/kg with 3 kinds of spiked levels. Conclusion The accuracy, precision, and sensitivity of the method meet the requirements for residue detection.

Objective To study the characterization and antioxidant activity of Maillard reaction products of autolytic peptides from Stichopus japonicus. Methods The autolysis phenomenon of Stichopus japonicus was taken to dissolve their body walls. Further used D-xylose and Stichopus japonicus autolytic peptides for Maillard reaction to modify autolytic peptides, and the physical and chemical properties and antioxidant activity differences of the Maillard reaction products were analyzed. Results The Maillard reaction conditions were as follows: Reaction time 4 h, reaction temperature 120 ℃, mass ratio of Stichopus japonicus autolytic peptides to D-xylose 1:2. After the reaction, the content of free amino group decreased from (32.35±1.90) μg/mL to (12.68±1.10) μg/mL. The maximum fluorescence emission peak of the Maillard reaction products shifted from 401 nm to 434 nm, and an absorption peak appeared at 288 nm in the ultraviolet absorption spectrum. The molecular weight measurement showed that the large molecular weight material above 3600 u increased significantly. The appearance of the Maillard reaction products from the autolytic peptides of Stichopus japonicus and D-xylose was verified. When the mass concentration of Maillard reaction products was 8 mg/mL, the scavenging ability of hydroxyl free radical, 1,1-diphenyl-2-picrylhydrazine (DPPH) free radical and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) cation free radical were above 85%, and the reducing ability of Fe³⁺ was 6.3 times higher than that of autolytic peptides from Stichopus japonicus before the reaction. Conclusion The results provide a new reference for utilizing the autolysis of Stichopus japonicus and improving the antioxidant activity of the Stichopus japonicus autolytic peptides.

Objective To rapidly and non-destructively detect aflatoxin in mildly moldy Zea mays using near-infrared spectroscopy (NIRS) technology. Methods Mildly moldy Zea mays samples were selected as experimental materials, with the content of aflatoxin B₁ (AFB₁) as the detection indicator. A total of 153 sample images were collected using the NIRS imaging acquisition system. Three kinds of preprocessing methods, including multiplicative scatter correction, standard normal variate transformation, and moving average smoothing (MAS), were applied to preprocess the raw near-infrared spectral data (RNSD). Backpropagation neural network (BPNN), extreme learning machine, and support vector machine were employed to model and analyze the preprocessed spectral data along with AFB₁ content data, evaluating the impact of preprocessing methods on model performance. Furthermore, the stepwise projection algorithm (SPA) was performed to select characteristic spectra from the preprocessed data for comprehensive comparison after incorporating them into the models. Results The optimal spectral preprocessing method was MAS. Ten characteristic spectra were selected through SPA, and the BPNN model exhibited the best prediction results, achieving a coefficient of determination of 0.932 and a relative prediction deviation of 3.922. This model demonstrated good performance and reliability. Conclusion It is feasible to determine AFB₁ content in mildly moldy Zea mays using NIRS technology. The findings of this study provide an important reference for the application of NIRS in identifying other agricultural products.

Objective To investigate the effects of different storage conditions on the water migration and volatile component changes of Zea mays, and to screen out characteristic volatile components. Methods Low field-nuclear magnetic resonance (LF-NMR) and gas chromatography-ion mobility spectrometry (GC-IMS) technology were used to study the changes in micro moisture, volatile component composition, and relative content of Zea mays under controlled temperature and humidity conditions. Results With the extension of storage time, moisture, fatty acid value, starch, and alcohol soluble protein indicators all undergo certain changes. When stored for 30 days, the moisture content reached equilibrium; the maximum value of fatty acid value was 46.11 mgKOH/100 g when stored at 65% RH for 90 days at 30 ℃, and the fatty acid value was still suitable for storage after 120 days; storing at 20 ℃ was beneficial for the accumulation of starch content; alcohol soluble proteins were significantly affected by temperature; under 65% RH conditions, as the storage temperature increased, the bound moisture content gradually decreased, resulting in the transformation of T20 strongly bound water to T21 weakly bound water and T22 strongly bound water to T23 weakly bound water; under 55% RH conditions, as the storage temperature increased, the bound water content gradually decreased, and the changes in the peaks of non flowing water and free water were consistent with those of bound water; the volatile components in the sample were classified as acids (2 types), aldehydes (20 types), ketones (15 types), alcohols (15 types), esters (12 types), furans (2 types), olefins (3 types), and amines (1 type). Conclusion As the storage temperature increases, the ability of Zea mays to retain moisture gradually weakens, while as the humidity increases, its ability to retain moisture increases. The high temperature and high humidity environment promotes the release of volatile components such as aldehydes and alcohols, while ketones and esters decrease. The 3-pentanone, 1-octen-3-one-M, 1-butanol, 3-methyl-D, 1-hexanol-D, isovaleric acid, methyl ester can be used as characteristic volatile components to distinguish mold growth in high moisture Zea mays, providing reference for the identification of mold growth in high moisture Zea mays.

Edible agricultural products are primary products derived from agriculture, forestry, livestock husbandry and fishery, which are important components of people's daily diet. The widespread use of pesticides in recent years has effectively promoted agricultural development, but the problem of pesticide residue pollution caused by illegal use of banned or restricted pesticides and unscientific pesticide application has attracted considerable attention to the safety of edible agricultural products. As an agricultural powerhouse, China has a fairly comprehensive range of pesticides, and new pesticides are constantly emerging. Therefore, effective regulation of pesticide residues in edible agricultural products, as well as exploration of more convenient, quick, efficient, and sensitive detection methods, has become an important research topic for the inspection and testing industry. This paper briefly summarized pesticide residues in edible agricultural products, focused on the relevant technical methods of pesticide residues detection in edible agricultural products, and looked forward to new detection technologies and methods, in order to provide references for improving the detection of pesticide residues in edible agricultural products, and ensure food safety and people's health.

Objective To develop an ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the determination of pentachlorophenol sodium residues in aquatic products. Methods The sample preparation involved extraction with 80% acetonitrile in water containing 5% triethylamine, followed by purification using Waters Oasis MAX solid-phase extraction cartridges. After elution with a 4% formic acid in methanol solution, the pentachlorophenol sodium was analyzed by UPLC-MS/MS using a Waters XBridge C18 column (100 mm × 2.10 mm, 3.50 µm). The mobile phases consisted of A: 0.1% formic acid in water (containing 5 mmol/L ammonium acetate) and B: acetonitrile. Quantification was carried out using the external standard method. The recovery of pentachlorophenol sodium in the muscle of Ctenopharyngodon idella and the eatable part of Eriocheir sinensis matrices was examined. Results The linear range of the pentachlorophenol sodium residue detection method in Ctenopharyngodon idella and Eriocheir sinensis was 0.2 to 8.0 ng/mL (r²>0.999). The limit of detection was 0.5 μg/kg and limit of quantification was 1.0 μg/kg, respectively. The recoveries at spiking levels of 1.0, 2.0, and 10 μg/kg were within the range of 77.0% to 105%. Intra-assay relative standard deviations ranged from 2.51% to 7.62% (n=6), and inter-assay relative standard deviations ranged from 3.36% to 6.48% (n=3). Conclusion The developed UPLC-MS/MS method for the determination of pentachlorophenol sodium residues in Ctenopharyngodon idella and Eriocheir sinensis matrices is highly sensitive, accurate, and precise, with good repeatability and reproducibility, and is therefore suitable for the detection of pentachlorophenol sodium residues in aquatic products.

Objective To prepare a polydopamine (PDA)-based lateral flow immunochromatography assay for the highly sensitive detection of deoxynivalenol (DON) in cereals. Methods In this paper, PDA was synthesized by dopamine self-oxidative polymerization, and the PDA labeled monoclonal antibody (PDA-mAb) probe was prepared by a one-step conjugation method. Subsequently, the PDA lateral flow immunochromatography assay was established using DON antigen as the test line (T line) and goat anti-mouse antibody as the control line (C line). Results The results showed that the cut-off value of the PDA lateral flow immunochromatography assay for detecting DON was 6.0 ng/mL, the visual limit of detection was 0.9 ng/mL, half maximal inhibitory concentration was 1.13 ng/mL, which were 0.88 times and 3.08 times higher than those of fluorescent microsphere test strip and colloidal gold test strip, respectively. Meanwhile, the PDA lateral flow immunochromatography assay possessed well stability and specificity. In addition, the proposed lateral flow immunochromatography assay has been successfully used for the detection of DON in corn, millet, and oats samples, with minimum detection limits of 8.40, 6.87, and 9.89 μg/kg, recoveries ranging from 80.10%-122.05%, and relative standard deviations less than 12.01%. Conclusion In summary, the PDA lateral flow immunochromatography assay established in this work is sensitive, accurate, rapid and simple, and provides technical support for the detection of mycotoxins in cereals.

Objective To optimize the process of spray drying pomelo powder and the formula of compound pomelo tea powder. Methods This study focused on optimizing the de-bittering process of pomelo peel powder and the spray drying parameters of pomelo powder, using sensory evaluation as key indicators. Subsequently, compound pomelo tea powder was made using maltodextrin, spray-dried pomelo pulp powder, pomelo outer peel powder, anhydrous citric acid, white sugar, and jasmine tea powder as raw materials. The formulation and production process of the compound pomelo tea powder were optimized through single-factor experiments and orthogonal experiments, with dispersibility and sensory evaluation serving as the key indicators. Results The optimal de-bittering process was achieved by treating pomelo peel in a water bath at 50 ℃ for 40 minutes with the addition of 1.8% β-cyclodextrin. The spray drying parameters were optimized with an inlet temperature of 160 ℃, an outlet temperature of 60 ℃, a feed flow rate of 2 mL/min, an air velocity of 3 m³/min, and an air pressure of 0.1 MPa. The final formulation of compound pomelo tea powder included 0.6% of pomelo pulp powder, 0.2% of pomelo outer peel powder, 0.1% of jasmine tea powder, 5% of sugar, 0.05% of anhydrous citric acid, and 0.4% of maltodextrin. The optimized product demonstrated excellent dispersibility 13.19 s, a high sensory evaluation score 76.3, and an overall score of 97.45, while retaining the distinct aroma of pomelo and the flavor of jasmine tea. Conclusion This process offers a promising approach for the industrial production of high-quality compound beverages.

Objective To characterize the composition of amino acids in fish dishes consumed by Liaoning Province residents and to evaluate their nutritional value. Methods The 7 kinds of representative fish dishes for daily consumption were selected, the amino acid composition and content of fish dishes were determined by conventional acid hydrolysis and alkaline hydrolysis methods using a fully automated amino acid analyzer, the amino acid score and amino acid ratio coefficient methods were used to evaluate the comprehensive nutritional value and to analyze the content of essential amino acids in a clustered heat map. Results The 7 kinds of fish dishes had complete amino acid types, with a total amino acid content ranged from 92.88 to 190.00 mg/g; the essential amino acid content ranged from 36.09 to 74.14 mg/g; the ratio of the essential amino acid to the total amino acid ranged from 0.39 to 0.41; and the total content range of sweet amino acids and umami amino acids ranged from 51.23 to 103.37 mg/g. The evaluation of amino acid scores and ratio coefficients showed that the composition of essential amino acids in the 7 kinds of fish dishes was balanced and abundant. The clustering heat map divided the 7 kinds of fish dishes into two categories according to the content of essential amino acids. Conclusion Although there is variability in the amino acid content and nutritional value of fish dishes consumed daily by Liaoning residents, they all contain a wide variety of amino acids with high nutritional value. They can be used as high-quality protein sources. This study can provide a scientific value for the nutritional value analysis of finished dishes.

Tetracycline antibiotics are widely used in animal husbandry, and their main ways of entering milk are through environmental exposure and direct ingestion by cows. Tetracyclines accumulate toxicity through the food chain and pose a threat to human health. Molecular imprinting technology can customize high molecular network polymers that specifically bind to tetracyclines, with many advantages such as high selectivity, good mechanical properties, low cost, high temperature and acid-base resistance, and reusability. It plays an important role in the detection of tetracycline residues in milk. The combination of molecular imprinting and solid-phase extraction technology can simplify the pretreatment process, optimize methods, and effectively solve the separation and purification problems caused by the complexity of milk matrix, including four solid-phase extraction and chromatography techniques: Solid-phase extraction, solid-phase microextraction, dispersed solid-phase extraction, magnetic solid-phase extraction, etc. The specific recognition ability based on molecular imprinting technology combined with sensors (including 5 types of sensors: Molecular imprinting electrochemistry, fluorescence, photonic crystal, plasma resonance, and photoelectric sensors) can improve selectivity, stability, and response speed. The operation is simple, especially suitable for rapid screening on site. This article introduced the research progress of the above-mentioned technologies and sensors in detecting tetracycline residues in milk, analyzed and discusses their application effects, and pointed out the future direction of molecular imprinting technology in this field, providing reference for subsequent research and application.