Objective To optimize the mixed acid extraction process of pectin from Akebia trifoliate peel and evaluate the structure, and antioxidant properties of pectin. Methods Using Akebia trifoliate peel as raw material, which was extracted by the mixed acids hydrolysis. The effects of the types of inorganic acids, the volume ratio of the mixed acid, solid-to-liquid ratio, pH, extraction time and temperature were studied, and Box-Behnken response surface method was used to optimize the extraction process parameters on the basis of single factor experiment. The structure of the peel pectin of Akebia trifoliate obtained under the optimal extraction conditions was characterized by ultraviolet-visible spectroscopy (UV-Vis) and Fourier transform infrared spectroscopy (FT-IR), and its antioxidant activity was investigated. Results The optimal extraction conditions were: The volume ratio of the mixed acid [V(citric acid):V(sulfuric acid)] 2:1, solid-to-liquid ratio 1:30 (g:mL), pH value 1.0, extraction time 2.0 h and temperature 94 ℃, and the extraction rate reached 14.22%, which were about 1.24% and 4.17% increase compared with single sulfuric acid and citric acid, respectively. FT-IR showed that the absorption peaks of sulfuric acid and citric acid extraction of pectin (CSEP) were more consistent with its structural characteristics than sulfuric acid extraction of pectin (SEP) and citric acid extraction of pectin (CEP) at 1754 cm^-1 and 1624 cm^-1, and its content of galacturonic acid (81.94%) and degree of esterification (82.41%) more higher. CSEP own superior antioxidant biological activity, and the half maximal inhibitory concentration (IC₅₀) for hydroxyl radical of CSEP was lower than that of commercial pectin (CP), which were 2.248 mg/mL and 4.114 mg/mL, respectively. Conclusion Using the mixed acid to extract pectin from Akebia trifoliata peel has good improved on extraction rate, content of galacturonic acid and antioxidant activity.

Objective To study the preparation and physicochemical properties of polypeptide-selenium chelate from Juglans regia L.. Methods Juglans regia L. protein was extracted by alkali-soluble acid precipitation method, and Juglans regia L. polypeptide was prepared by alkaline protease. Juglans regia L. polypeptide reacted with sodium selenite to produce Juglans regia L. polypeptide-selenium chelate. The preparation technology was optimized by single factor test and orthogonal test. Results When the mass ratio of polypeptide to sodium selenite was 3:1, the chelating temperature was 45 ℃, the chelating time was 50 min, and the pH was 8, the chelating rate was 58.99%±1.44%. The chelate was resistant to heat, acid and alkali, had good digestive stability and high bioavailability of selenium. Compared with Juglans regia L. polypeptide, Juglans regia L. polypeptide-selenium chelate had stronger scavenging ability of 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical, hydroxyl free radical and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation free radical. Conclusion In this study, Juglans regia L. polypeptide-selenium chelate is successfully prepared through optimized synthesis conditions. The resulting complex demonstrates favorable physicochemical properties and significant antioxidant capacity, providing a potential raw material reference for developing selenium-enriched nutritional supplements.

Objective To optimize the enzyme-assisted extraction process of Eucommia ulmoides leaf extract, and evaluate its antioxidant and hepatoprotective activities. Methods Using Eucommia ulmoides leaves as raw material, the enzyme-assisted extraction technique was employed to optimize the extraction process. The antioxidant activity of the extract was evaluated through 1,1-diphenyl-2-picrylhydrazine (DPPH) radical scavenging rate, hydroxyl radical scavenging rate, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging rate, and total antioxidant capacity assays. The hepatoprotective activity was assessed using a zebrafish model. Results Under the conditions of a solid-to-liquid ratio of 1:20 (g:mL), enzymolysis temperature of 50 °C, enzymolysis time of 4 h, and enzyme dosage of 3%, the yield of Eucommia ulmoides leaf extract was 32.15%±0.36%, with a theoretical yield of 31.781%. The small difference between the actual and theoretical yields indicates the reliability of the extraction parameters. In vitro antioxidant activity tests showed that, within the experimental mass concentration range, the extract exhibited significant antioxidant activity, effectively scavenging DPPH radicals, hydroxyl radicals, and ABTS radicals. Zebrafish experiments demonstrated that the extract at mass concentrations of 100 μg/mL and 200 μg/mL protected against thioacetamide (TAA)-induced liver injury, indicating notable hepatoprotective activity. Conclusion The Eucommia ulmoides leaf extract obtained through enzyme-assisted extraction possesses excellent antioxidant and hepatoprotective activities. This study provides technical support for the further application and promotion of Eucommia ulmoides leaves in the food field.

Objective To determine the content of 27 kinds of inorganic elements in commercially available Solanum tuberosum L. in Qinzhou City and evaluate the situation of heavy metal pollution. Methods Quantitative analysis of 27 kinds of inorganic elements in Solanum tuberosum L. was conducted using the inductively coupled plasma mass spectrometry method from GB 5009.268—2016 National food safety standard—Determination of multiple elements in foods. The safety of the samples and the distribution of characteristic elements were comprehensively evaluated by combining the single-factor pollution index method, Nemerow comprehensive index method, and chemometrics based on the toxicity of the elements. Results The commercial Solanum tuberosum L. from Qinzhou City contained abundant trace elements, including the essential constants of human body such as Na (7.50-458.20 mg/kg), Mg (66.40-429.40 mg/kg), K (1620.80-7397.60 mg/kg), Ca (15.00-123.60 mg/kg); essential trace elements such as Mn (0.46-5.16 mg/kg), Fe (3.00-142.10 mg/kg), Cu (0.24-1.12 mg/kg); hazardous elements such as Pb (0-0.08 mg/kg), Cd (0-0.03 mg/kg), As (0-0.08 mg/kg), Cr (0-0.32 mg/kg). The hazardous elements Hg, Sn, Ni were not detected. The content of potentially harmful elements was low, indicating good safety. Single-factor pollution index and Nemerow comprehensive index analyses demonstrated that the single-factor pollution index values and Nemerow comprehensive index values for Pb, Cd, total Hg, total As, and Cr in all samples were less than 0.7, categorizing them as excellent grade with safe pollution levels. Principal component analysis identified Li, Al, Ti, V, Cr, Mn, Fe, As, Mg, K, Cu, Zn, Na, Ca and Sr as characteristic inorganic elements. Cluster analysis classified the samples into two major categories. Conclusion The Solanum tuberosum L. are sold in the market in that city, which has a very low content of harmful elements and a low degree of pollution, and the content does not exceed the limit requirements of GB 2762—2022 National food safety standard—Maximum levels of contaminants in foods. Therefore, all the tested Solanum tuberosum L. samples are safe food, and their growing environment is not polluted by heavy metals.

Mycotoxins are secondary metabolites produced by fungi, which accumulate in the food chain and enter the human body, endangering human health. In recent years, nanozymes with controllable morphology and enzyme-mimicking activity have shown significant advantages in the detection of mycotoxins. This paper mainly summarized the application research of nanozyme biosensors in the detection of mycotoxins, divided nanozymes into metal oxide-based, noble metal-based and carbon-based nanozymes according to the material components, analyzed the dynamic regulation mechanism of nanostructure parameters (including size, morphology, surface modification) on enzyme-mimicking activity, and then explored the technical advantages of nanozymes in colorimetric, fluorescence, electrochemical and Raman detection, revealing its application potential in the rapid detection of mycotoxins. In addition, this paper prospected the application of biosensors constructed by nanozymes in the detection of mycotoxins, aiming to provide theoretical support and technical foresight for the application of nanozymes in the field of food safety detection, and it was expected to provide guidance for the industrial development of the detection field.

Objective To establish a rapid visual detection method for Aspergillus niger in Zea mays L. by loop-mediated isothermal amplification (LAMP) technology. Methods Based on LAMP technology, specific primers targeting the key ochratoxin A (OTA) biosynthesis gene OTAhal were designed. Through screening of the primers and optimization of conditions such as primer sequence, primer ratio, reaction temperature and visual dye, the optimal detection conditions were determined. Using the total DNA of Aspergillus niger and artificially contaminated corn samples as templates, the sensitivity of the detection method and the feasibility of its practical application were validated. Results The optimal primer ratio was 8:4:1, the optimal reaction temperature was 64 °C, and the method could complete the amplification of target DNA within 30 minutes. The color of the positive sample changed from violet to blue-purple. This method could detect DNA concentrations as low as 6.87×10⁻³ ng/μL. When applied to actual Zea mays L. sample testing, it achieved a detection limit as low as 10¹ spores/mL. Conclusion This method is simple to operate, highly sensitive, and does not require sophisticated instruments. It can be applied to the detection of OTA in actual Zea mays L. samples, indicating broad application prospects.

Objective To explore the application areas of rapid detection technology for core quality indicators in cheese and its products using near-infrared spectroscopy (NIRS), and validating the feasibility of NIRS for rapid testing of cheese quality parameters. Methods Four types of common processed cheese products (cheese sticks, cheese slices, cream cheese, Mozzarella) were selected for experimentation and divided into modeling and validation sets; modeling experiments were conducted using samples from the modeling set on a single-brand instrument; synchronous national standard detection and multi-instrument NIRS detection comparative analysis were performed using instruments from 4 different manufacturers on the validation sets. Results For modeling, multidimensional prediction models for core indicators (protein, fat, moisture, pH) were successfully constructed by comparing the modeling mechanisms of algorithms like partial least squares regression (PLSR), with the coefficient of determination exceeding 0.85. For validation, the average deviations between the NIRS detection results (protein, fat, moisture) obtained using 4 kinds of NIRS spectrometers on different cheese products and those determined by national standard methods met equivalence requirements except for the protein deviation (>10%) of Mozzarella on instrument No.1; precision also met the requirements of national standard methods. Conclusion The application of NIRS spectroscopy equipment for rapid detection of core quality indicators in cheese and its products is feasible; NIRS spectroscopy technology can serve as an effective supplement to traditional chemical detection methods for rapid analysis of cheese composition, offering greater potential for high-efficiency, low-cost, and environmentally friendly testing.

Objective To construct a novel fluorescent aptamer sensor based on MXene nanomaterials by combining X-type DNA with aptamers for the simultaneous detection of Pb²⁺ and Cd²⁺ in food. Methods X-type DNA structures were prepared by complementary base pairing, and in the presence of Pb²⁺ and Cd²⁺, the aptamer within the X-type DNA structure specifically bound to the target ions and triggers desorption from the MXene surface, thereby restoring the fluorescent signal. Results Under the optimal experimental conditions, the fluorescence signal intensity was linearly correlated with Pb²⁺ and Cd²⁺ in the range of 0.5-500.0 nmol/L, with the limits of detection were 0.33 nmol/L and 0.28 nmol/L, respectively, and the results showed that the sensor had good working performance. Conclusion The fluorescent biosensor prepared in this study has been successfully applied to the spiked analysis of tap water and cornmeal with good recoveries, indicating that it can be used as an effective tool for the detection of Pb²⁺ and Cd²⁺ in food.

Objective To optimize the frying formulation and process of rice bran-enriched chicken cutlets. Methods Taking sensory evaluation as the assessment criteria, single-factor experiments were conducted to examine the effects of rice bran addition amount, wheat flour and corn starch ratio, frying temperature and frying time on the quality of fried chicken cutlets. Orthogonal experiments were employed to optimize the addition amounts and process parameters. Data analysis was performed using IBM SPSS Statistics 20, with P<0.05 indicating statistically significant differences. Origin was used for graphical visualization. Results The order of influence of various factors on the sensory quality of fried chicken chops was: Frying temperature>frying time>wheat flour and corn starch ratio>rice bran addition. The frying conditions were determined by comprehensive consideration: Rice bran addition 0.8% (m:m), wheat flour and corn starch ratio 1:1 (m:m), frying temperature 180 ℃, frying time 2 min. The sensory score of fried chicken chops under this condition was 90.1 points. The fried chicken chops had uniform golden color, rich aroma, moderate hardness, good brittleness and sensory quality. Conclusion It is feasible to add rice bran to the traditional coating formula, which can provide a theoretical basis for mass production industrialization.

Objective To establish a method for the determination of 9 kinds of organic acids (oxalic acid, tartaric acid, quinic acid, malic acid, lactic acid, citric acid, fumaric acid, succinic acid and gallic acid) in fruits and vegetable crisps by liquid chromatography-high resolution mass spectrometry (LC-HRMS). Methods The samples were cleaned up by a SAX solid-phase extraction column. The samples were eluted with 0.1% formic acid in water and methanol as mobile phases and separated on an Eclipse Plus C₁₈ column (4.6 mm×250 mm, 5 μm), and monitored in electron spray ionization (ESI)- mode and quantified by external standard method. Results The calibration curves for 9 kinds of organic acids showed good linearity in the concentration range of 50-5000 ng/mL. The correlation coefficients (r) were all greater than 0.9991, the limits of detection (LODs) were in the range of 1-10 ng/mL, the limits of quantitation (LOQs) were in the range of 10-50 ng/mL, the spiked recoveries were in the range of 96%-98%, and the relative standard deviations (RSDs) were in the range of 1.5%-4.9%. Among them, lactic acid [(16.16±0.30) mg/g] and citric acid [(15.53±0.11) mg/g] were the main organic acids in the fruit and vegetable crisps, and their content was significantly higher than those of other organic acids. In contrast, tartaric acid [(1.29±0.11) mg/g] and oxalic acid [(1.56±0.25) mg/g] were found at lower levels. Conclusion The method is simple, rapid, and accurate and can be used for the qualitative and quantitative determination of organic acids (oxalic acid, tartaric acid, quinic acid, malic acid, lactic acid, citric acid, fumaric acid, succinic acid and gallic acid) in fruit and vegetable crumbles as well as other food.