Objective To establish an analytical method for the determination of flonicamid residues in tea and assess the dietary intake risk of flonicamid in tea. Methods Flonicamid residues in tea were extracted using acetonitrile, followed by dehydration and salting out with anhydrous MgSO₄ and sodium acetate. The supernatant was purified using anhydrous MgSO₄, C₁₈, primary-secondary amine (PSA), and graphitized carbon black (GCB) as adsorbents. Analysis was performed using ultra performance liquid chromatography-tandem mass spectrometry in multiple reaction monitoring mode with positive ionization. Quantification was achieved using matrix-matched external standards. Dietary intake risk assessment was conducted based on residue trial results and the dietary structure of the Chinese population. Results Flonicamid had a good linear relationship (r≥0.9999) within a certain concentration range. At levels of 0.01, 0.50, 20.00 and 30.00 mg/kg, the average recovery rates of tea (dry and fresh) ranged from 83.9%-93.6%, with relative standard deviations of 1.1%-5.3%. The limit of quantitation was 0.01 mg/kg. The final residue test and degradation test showed that the residual amount of flonicamid on tea was mainly affected by the combined effects of application dose and harvesting interval. The half-lives of flonicamid in fresh and dry tea in various regions were between 0.8-4.0 d and 0.8-5.1 d, respectively, indicating that it was an easily degradable pesticide. The results of the dietary assessment showed that the estimated daily intake of flonicamid through tea consumption for adults over 18 years old was between 0.74-0.81 μg/(kg·bw·d), which accounted for 1.05% to 1.16% of acceptable daily intake; combining the registration status of pesticides in China and the existing residue limits, the national estimated daily intake of flonicamid for the general population was 58.5193 μg/(kg·bw·d), which accounted for 83.6% of the acceptable daily intake. Flonicamid had low acute toxicity, and the probability of causing acute dietary risk was minimal. Therefore, there was no need to conduct an acute dietary risk assessment. Conclusion This method has simple pretreatment steps, high accuracy and high sensitivity, and can be used for the detection of flonicamid residues in tea. Upon evaluation, it has been determined that flonicamid does not pose an unacceptable risk to the general population.

Objective To evaluate the pollution levels of five harmful heavy metals in different tissue parts and whole crabs of imported Cancer pagurus (common yellow crabs), clarify their distribution characteristics and food safety risks. Methods According to the national standard GB 5009.268—2016 National food safety standard-Determination of multielements in food, inductively coupled plasma mass spectrometry (ICP-MS) was used to detect the content of arsenic, cadmium, chromium, mercury, and lead in 9 parts of Cancer pagurus liver, pancreas, crab roe, crab gills, crab body meat, crab leg meat and whole crab. The differences in heavy metal enrichment and exceedance in different parts were analyzed. Results Cadmium pollution was the most prominent, with the highest content in the liver and pancreas (up to 98.60 mg/kg) and a exceedance rate of 95.0%; arsenic was commonly detected but there was no clear limit standard, while mercury and lead only exceed the limit in inedible parts such as crab gills; the overall heavy metal content was cadmium>arsenic>mercury>lead>chromium, and the content of edible parts (crab body meat, crab leg meat) was significantly lower than that of non edible parts; the heavy metal content in whole crabs was significantly affected by highly polluted areas such as the liver and pancreas. Conclusion Imported Cancer pagurus pose a high risk of cadmium enrichment in suspected edible parts such as the liver, pancreas and gonads. It is necessary to improve the definition criteria for edible parts and establish a targeted risk assessment mechanism. It is recommended that consumers reduce their intake of highly contaminated parts. This study provides data support for optimizing the safety supervision strategy and dietary guidance of imported crustacean aquatic products.

Dandelion is a medicinal and food plant in China, with a wide range of sources and rich nutritional and pharmacological values. Dandelion polysaccharide is one of the important functional active ingredients, and domestic and international studies have found that it has a variety of biological activities. This paper systematically reviewed the extraction and purification methods of Dandelion polysaccharides, analyzed the primary structural features of Dandelion polysaccharides, such as molecular weight, monosaccharide composition and chemical structure, and summarized and analyzed the biological activities and related mechanisms of Dandelion polysaccharides, such as antioxidant, anti-bacterial, immune regulation, hypoglycemia, anti-inflammatory and anti-tumor, etc., and explored the conformational relationship between the structure of Dandelion polysaccharides and its biological activities, which is aimed to provide the basis for the deep development of Dandelion polysaccharides in food and medicine. This study aims to provide important theoretical references for the development and application of Dandelion polysaccharides in food and medicine.

Objective To establish a method for the simultaneous determination of 11 kinds of synthetic colorants in beverages by automated solid-phase extraction-liquid chromatography. Methods The 2 g of the beverage sample was taken, it was extracted with an ammonia ethanol solution, and operations such as activation, sample loading, washing, eluting and collection were performed in turn with the help of a fully automatic solid-phase extraction instrument. After nitrogen blowing and redissolution, the liquid chromatography instrument was used for on-line determination [diode multi-wavelength multi-channel simultaneous detection, detection wavelengths 415 nm (citrus yellow and quinoline yellow), 520 nm (new red, amaranth red, carmine, sunset yellow, temptation red, acidic red, and red algae), 610 nm (indigo and bright blue); mobile phase: A 20 mmol/L ammonium acetate solution, B methanol, flow rate 1 mL/min, gradient elution]. Results In the range of 0.2-10.0 μg/mL, the mass concentration of 11 kinds of synthetic colorants showed good linear relationship with peak area, and the linear correlation coefficients were all greater than 0.99, the limit of detection met the requirements of GB 500935—2023 National food safety standard-Determination of synthetic colorants in food. In the standard addition method recovery test, the recovery rates were between 91.3% and 106.0%, and the relative standard deviation of the determination value (n=6) was less than 5.0%. This method was applied to the ability verification of sunset yellow and carmine in beverages in food testing institutions in the Yangtze River Delta. The content of carmine was 5.86 mg/kg, and the content of sunset yellow was 4.31 mg/kg. The other synthetic colorants were not detected. Conclusion This method achieve good enrichment effect, high automation degree, simple operation, good stability, short time, high efficiency, good sensitivity, high accuracy and good reproducibility, and is suitable the determination and analysis of synthetic colorants in a large number of beverages.

Objective To develop a sensitive and stable dual signal output indicator label and realize real-time monitoring of the freshness of Litopenaeus vannamei. Methods Based on polyvinyl alcohol (PVA)/agar composite matrix combining anthocyanins (ACNs), silver coated gold nanoparticles (Au@AgNPs) and the metal organic framework material UiO-66, the dual signal output indicator labels were prepared by casting method. Next, the stabilizing effect of UiO-66 on the labels was investigated by storage stability, ultraviolet stability and anti-migration experiments. Ammonia, dimethylamine and trimethylamine were used as characteristic volatile markers to evaluate the gas sensitive response performance of the labels. Ultimately, the label was applied to real-time monitoring of the freshness of Litopenaeus vannamei. Results Compared to labels without UiO-66, the addition of UiO-66 effectively immobilized the anthocyanins and improved the UV stability and storage stability of the label. In addition, the label showed excellent responsiveness to ammonia and amine gases. In the application of freshness monitoring of Litopenaeus vannamei, the color of the indicator label gradually changed from purplish-red to bluish-green with the change of freshness of Litopenaeus vannamei. The partial least squares regression (PLSR) model based on the surface-enhanced Raman scattering (SERS) signals showed excellent prediction performance for the total volatile basic nitrogen (TVB-N) values, with a correction set coefficient of calibrated coefficient of determination (R²_C) of 0.951, cross-validated coefficient of determination (R²_CV) of 0.899, predicted coefficient of determination (R²_P) of 0.966, and residual prediction deviation (RPD) of 4.765. Conclusion A colorimetric-SERS dual-signal output indicator label is developed in this study. The label enable simultaneous visual identification of the freshness of Litopenaeus vannamei and high-sensitivity prediction of TVB-N values, providing a reference for the design of novel intelligent food packaging systems.

Objective To optimize the subcritical water extraction process of Pollen pini polysaccharides based on genetic algorithm-neural network (GA-NN) algorithm and further explore its anti-fatigue activity. Methods Using broken shell Pollen pini as raw material, a response surface was designed through Box-Behnken test on a single factor basis, and a network neural model was constructed and optimized using GA-NN algorithm. Under the optimal process conditions, the anti-fatigue effect of polysaccharides was evaluated through mouse weight-bearing swimming test. Results The relative error and coefficient of determination (R²) of the constructed neural network model were 0.03267 and 0.98476, respectively. The genetic algorithm was iterated 60 times for subcritical water extraction of polysaccharides, and the optimal parameters were obtained as follows: Temperature 148 ℃, time 28 min, liquid to material ratio 40:1 (mL/g), pressure 5 MPa, and polysaccharide yield of 23.7893 mg/g. After verification, there was no significant difference between the actual value and the predicted value, indicating good accuracy of the model. The study on anti fatigue activity showed that compared with the blank group, the high-dose group of mice had a certain degree of increase in body weight, while there was no significant difference in other groups (P>0.05). Compared with the blank group, the swimming time of mice in the polysaccharide group was prolonged, the levels of blood lactate and urea nitrogen were reduced, and the reserves of muscle glycogen and liver glycogen were significantly increased (P<0.05). Conclusion GA-NN can effectively optimize the subcritical water extraction process of Pollen pini polysaccharide, and the polysaccharide has a certain anti fatigue effect.

Objective To investigate the current status of veterinary drug residues in eggs on sold in Banan District, Chongqing and assess the health risk of residues’ dietary intake residues. Methods In 2024, a total of 208 egg samples were randomly collected from markets and supermarkets in 10 towns and streets of Banan district. The residues of 15 kinds of veterinary drugs were detected using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The point assessment method was employed to calculate the daily estimated exposure and hazard quotient for dietary exposure risk assessment. Results The detection rate of veterinary drug residues in 208 samples of market eggs was 8.65% (18/208), with doxycycline showed the highest detection rate at 3.37% (7/208). The unqualified rate was 0.96% (2/208), with the unqualified samples mainly coming from unbranded bulk eggs sold in markets. The dietary exposure assessment revealed that the daily estimated exposure of veterinary drug residues ranged from 0.00013 to 0.03450 μg/(kg·bw·d), and the hazard quotient ranged from 0.00000 to 0.00872, significantly below the safety threshold. This indicates a low health risk associated with the intake of veterinary drug residues in eggs sold in the market. Conclusion Veterinary drug residues are detected in eggs sold in Banan District, Chongqing, but the residue is generally controllable and the health risk low. Special attention should be given to bulk and unbranded eggs, and standards for veterinary drug use and residue limits should be further refined.

Objective To establish a rapid detection model for the nutritional components of Oncorhynchus mykiss based on near-infrared spectroscopy (NIR). Methods Firstly, near-infrared spectral data of 200 Oncorhynchus mykiss were collected. Then, the content of 3 kinds of nutritional components (moisture, fat and protein) of each Oncorhynchus mykiss were determined by national standard methods. The near-infrared spectral data and nutritional component data were matched one by one. The near-infrared rapid detection model was established by combining NIR with partial least squares (PLS), and the best detection model was screened out. Results The pretreatment method of the moisture content detection model was multiple scattering correction (MSC), and the optimal model was obtained when the wavelength range was 4000-10000 cm^-1. The pretreatment method of the fat content detection model was standard normal variable (SNV), and the optimal model was obtained when the wavelength range was 5000-7144 cm^-1 and 7404-10000 cm^-1. The pretreatment method of the protein detection model was second derivative (ds2)+SNV+Savitzky-Golay smoothing (sg9), and the optimal model was obtained when the wavelength range was 4100-5100 cm^-1 and 5400-9000 cm^-1. The Q value, the correlation coefficient of the correlation coefficients, and the correlation coefficient of prediction of the optimal model were all relatively large, and the standard deviation of square error corrected and standard error of cross validation were close to each other, which met the best modeling principle. Conclusion The best model is verified by the prediction set that do not participate in the modeling. The absolute deviation between the predicted value and the true value (determined by the national standard method) is no more than 5.7%. This indicates that the model can be used for the detection of three nutritional components of Oncorhynchus mykiss, and can achieve non-destructive and rapid detection of the nutritional components of Oncorhynchus mykiss, saving detection costs and shortening the detection cycle.

Objective To establish a method for the rapid determination of total flavonoids in tartary buckwheat by cerium dioxide/multi-walled carbon nanotubes/acetylene black (CeO₂/MWCNTs/AB) nano-electrochemical sensor. Methods The modified material and these nanoelectrochemical sensors were characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical behavior of rutin on the electrode surface was systematically investigated via CV. Critical parameters were optimized, including electrolyte type, pH, modifier ratio, coating volume, accumulation time and scan rate. Results One pair of well- defined redox peaks were observed at the potential of 0.54 V and 0.57 V, which indicated that the electrochemical oxidation and reduction reaction of flavonoid was reversible. The experimental conditions were optimized, the results as follows: B-R solution with pH 2.0 as the electrolyte solution, V_CeO2/MWCNTs:V_{acetylene black} as 1:3, amounts of modified material, 12 μL, enrichment time as 9 min. At these conditions, the oxidation peak current of flavonoid linearly increased with its concentration, I_p=0.793C+3.508 (r²=0.998), and the limit of detection was 6.5×10^-8 mol/L. The developed method was used to determinate total flavonoids content of tartary buckwheat, the recoveries were in the range of 99.46%-102.15%, the results were superior to ultraviolet-visible spectrophotometry. Conclusion The method is feasible for the rapid and accurate determination of total flavonoids in food with the advantages such as simple pretreatment time saving and convenience, low detection cost, high sensitivity and good accuracy.

Objective To investigate the effects of different degree of low substitution degree on the physicochemical properties of potato starch, and apply it to the hard capsule shell to observe the effect of potato acetate starch on its properties. Methods Potato starch was used as raw material and acetic anhydride as esterifying agent to prepare esterification modified starch with different low degree of substitution (0.0143-0.0570). The physical and chemical properties and structural changes of different starch with low substitution degree were investigated, and it was used in the preparation of hard capsule shells. Results Both potato starches with different low substitution degrees and the original starch were shear-thinning type pseudoplastic fluids. The energy storage modulus and loss modulus of modified starch showed an increasing trend, and the storage modulus was larger than that of original starch. Compared with the original starch, the transparency, gel strength and water holding capacity of modified starch were improved. The swelling degree and solubility increased. The esterification reaction of acetic anhydride with potato starch occurred mainly on the surface of starch particles, and did not change the crystallization type of potato starch. The modified starch paste of potato was used to prepare the hard capsule shell and all the indexes met the requirements of Pharmacopoeia of the People’s Republic of China (2020 edition). Conclusion The low substitution degree of acetate starch can improve the performance and application range of natural starch, which is in line with the national food safety standards. The preparation of plant hard capsules instead of gelatin capsules can make up for the shortcomings of natural starch in the preparation process, and it is in line with the standards stipulated in Chinese pharmacopoeia.