Abstract:Objective: Improve 3D printing performance and gel properties of silver carp surimi system. Methods: By optimizing 3D printing parameters, the 3D printing process is associated with material rheological properties and 3D printing performance. The effects of sodium chloride addition on rheological properties, 3D printing properties, gel strength, moisture properties and microstructure of silver carp surimi were investigated. Results: The addition of sodium chloride decreased the loss modulus of surimi in a dose-dependent manner, but significantly improved the shear recovery performance, reduced the cooking loss of surimi system and increased the water retention of surimi system. The best gel strength and the densest microstructure of silver carp were obtained when the sodium chloride content was 2.5%. Conclusion: Adding proper amount of sodium chloride can improve the 3D printing performance and gel properties of surimi products.

Abstract:Objective: Explore the cryoprotective mechanism and structure-activity relationship of antifreeze peptides derived from silver carp parvalbumin. Methods: Using differential scanning calorimetry and molecular dynamics simulation to compare activity, structure and mode of action of two typical peptides. Results: Pv-AFP 1 （KAADSFNH KAFFAKVG） had a stable α-helix structure, while Pv-AFP 2 （KAADSFNHKAF） tended to exhibit random coil. The thermal hysteresis activity of Pv-AFP 1 was 0.87 ℃, which was higher than Pv-AFP 2 （0.74 ℃）. Molecular dynamics simulations showed that Pv-AFP 1 could interact with 53 water molecules, and could form 16 hydrogen bonds to adsorb onto the surface of ice crystals, with a binding energy of -1 514 kJ/mol, all were greater than Pv-AFP 2 （can bind 50 water molecules, adsorb on ice surface by forming 11 hydrogen bonds, with a binding energy of -805 kJ/mol）. Despite the similarity of the two peptide sequences, their major sites and modes of interactions with water molecules and ice crystals were somewhat different. In addition, both peptides could interact with ice/water interface and altered the curvature of the ice surface, thereby inhibiting water freezing. But Pv-AFP 1 showed a better inhibitory effect on ice surface growth than Pv-AFP 2, which was consistent with their thermal hysteresis activity. Conclusion: The activities of antifreeze peptides derived from silver carp parvalbumin might be related to their structural characters and their affinities, sites and modes of interaction with water molecules and ice crystals.

Abstract:Objective: This study aimed to improve the quality of brown rice. Methods: The content of γ-aminobutyric acid (GABA) and the activity of glutamate decarboxylase were used as indicators to study the effect of enrichment conditions on GABA content. Based on the optimal parameters, GABA content in each part of the grain was analyzed to reveal the migration law of GABA. Finally, the effect of the method on the quality of brown rice was analyzed and compared with the soaking method. Results: The highest GABA content was obtained when the water content of the raw material was 14.5% with the final moisture content of 20%, enrichment at 65 ℃ for 5 h. During the enrichment process, GABA was mainly generated in the bran layer and then migrated inward. The content of GABA in brown rice with different milling rates reached the peak at 5 h, but the migration rate tended to be stable after 4 h. The highest migration rate of GABA in endosperm was 87.1%. Compared with the soaking method, the brown rice enriched by the heating and humidifying method showed a yellower color, lower waist burst rate and softer cooked rice. Conclusion: The heating and humidification method is superior to the soaking method and can be used to prepare brown rice and white rice with high GABA content.

Abstract:Objective: To evaluate the effects of mechanical processing on the physicochemical properties of oat β-glucan and its in vitro fermentation. Methods: Oat coarse grains, oat flakes, and oat flour were respectively produced through mechanical progressing methods such as steel cutting, table pressing, and grinding. Then, scanning electron microscopy was used to observe the microstructure, the content, dissolution rate and relative molecular weight of oat β-glucan were determined, and the colon environment was simulated in vitro for fermentation. Results: The total β-glucan content and dissolution rate of steel-cutting oat were higher than those of untreated sample. The total β-glucan content of oat flake and oat flour were lower than untreated oat, but the dissolution rate was higher than it. Untreated oat showed a lower fermentation rate, with a significantly lower acid and gas production rate than those of steel-cutting oat, oat flake, and oat flour. The total short chain fatty acid content of untreated oat produced by fermentation was the lowest, but the content of propionic acid and butyric acid was significantly higher than the other three groups. Conclusion: Mechanical progressing can affect the in vitro fermentation characteristics of oats by altering the integrity of their cell wall structure, as well as the content and dissolution rate of β-glucan. Moderate processing can contribute to the health benefits of oats.

Abstract:Objective: This study aimed to explore the effect of different ultrasonic enhancement methods on the quality characteristics of dried lotus root in heat pumps. Methods: The effects of US, CU, and USOD on the drying characteristics, appearance color, microstructure, texture characteristics, nutritional quality and antioxidant characteristics of the lotus root heat pump during the drying process were investigated. Ultrasonic (US), direct contact ultrasound (CU), USOD and heat pump drying (HPD) were treated in series and parallel. The coefficient of variation method was used to comprehensively evaluate the quality of lotus root dried by different ultrasonic enhancement methods. Results: US, CU and USOD treatments had positive effects on the HPD speed of lotus roots. The brightness (L^*), polysaccharide content, and hydroxyl radical scavenging rate of lotus root obtained by USOD-HPD were the best, which were 77.98, 51.68 mg/g, and 45.94%, respectively. US-HPD treatment can better retain the content of flavonoids and vitamin C in lotus root. HPD lotus root had the highest polyphenol content and DPPH radical scavenging. The comprehensive evaluation results of the coefficient of variation method showed that the USOD-HPD lotus root had the best quality. Conclusion: The combined drying method of USOD-HPD can effectively improve the quality of lotus root.

Abstract:Objective: This study aimed to explore the aroma differences of Pixian bean paste from different brands and establish an analytical method for quality evaluation and quality control methods in Douban Sauce, based on solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) techniques along with sensory evaluation. Methods: Three different brands of Pixian Douban Sauce were selected as the research objects. SPME and GC-MS techniques were used to extract and qualitatively analyze the aroma components, and the sensory evaluation of the three types of Pixian Douban Sauce was conducted based on current effective group standards. Results: 57, 90, and 70 volatile flavor compounds were identified in brands T, J, and C Pixian Douban Sauce, and 46, 70, and 60 were identified in the database. Excluding impurity peaks and extremely low content fragment peaks, the flavor substances of brands T, J, and C are 32, 47, and 43, respectively. Brand J has the highest sensory rating, followed by brand T, and brand C has the lowest. Based on the analysis of aroma components and content, the relative content of 3-methylbutyraldehyde and 2-methylbutyraldehyde (both with apple aroma and a pleasant feeling) in brand J is higher than the other two brands, and only furfural with a relative content greater than 3% was detected in brand C. Conclusion: The combination of SPME-GC-MS technology and sensory evaluation analysis can distinguish the aroma components of different brands of Pixian Douban Sauce.

Abstract:Objective: The preparation method of matrix reference materials of bifenthrin and cyhalothrin pesticide residues in green tea was established. Methods: Green tea samples were sprayed with biphenylthrin and cyhalothrin. The samples were crushed, screened, homogenized and bottled. After the homogeneity and stability tests, the quantity value was determined by three laboratories, and the uncertainty was evaluated. Results: The amount values of bifenthrin and cyhalothrin in green tea were (0.185±0.019 7) and (0.207±0.046 6) mg/kg with k=2, and the confidence interval was 95%. Conclusion: The developed matrix reference materials of bifenthrin and cyhalothrin in green tea are homogeneous and stable enough, and the calibration results are reliable.

Abstract:Objective: To evaluate the antibiotic resistance of five foodborne Escherichia coli clinical isolates to ciprofloxacin, gentamicin and ampicillin. Methods: Based on the theory of electron transfer during bacterial energy metabolism and the introduction of resazurin as a redox probe, an electrochemical square wave voltammetry （SWV） method based on bladed tensin-mediated rapid identification of E. coli drug resistance was established. Results: The electrochemical square wave voltammetry values of E. coli at different concentrations mediated by resazurin were determined, and there was a good linear relationship between the E. coli concentration and the oxidized peak current （I） of resazurin in the range of 1.69×10²～1.69×10⁸ CFU/mL, with the regression equation of Y=-0.156 0X-2.965 5, and R²=0.977 5; When performing the determination of E. coli drug resistance, the drug sensitivity test standard was developed by Clinical and Laboratory Standards Institute （CLSI）. The oxidized peak current （I₀） of resazurin and the oxidized peak current （I_-a） obtained by E. coli after directly interacting with resazurin were used as the control, and the oxidized peak current （I_+a） obtained by E. coli after treating it with antibiotics and interacting with resazurin was determined. The value of bacterial activity V_ETA was introduced as V_ETA as an indicator for the identification of bacterial resistance by electrochemical square wave voltammetry, and established a rapid electrochemical drug sensitivity test method for E. coli mediated by resazurin. The established method was used to detect the resistance of five clinical isolates of foodborne E. coli to three antibiotics, and V_ETA=50 was used as the critical value for determining bacterial sensitivity and resistance, and the results of the drug sensitivity tests were all in accordance with the results of the paper diffusion method. The V_ETA=50 was used as the critical value for determining bacterial susceptibility and resistance, and all the results were consistent with the results of the paper diffusion method, and the paper diffusion method required 18 h to report the results, whereas this method required only 2 h. Conclusion: Our electrochemical square-wave voltammetry method based on the resazurin-mediated rapid discrimination of E. coli drug resistance is able to accurately and rapidly detect the antibiotics resistance of the five foodborne clinical isolates of E. coli to ciprofloxacin, gentamicin, and ampicillin.

Abstract:Objective: To astablish a strong popularity, high sensitivity of six human milk oligosaccharides in dairy product by precolumn derivatization high performance liquid chromatography-fluorescence method. Methods: Aquatic product sample was precipitated with glacial acetic acid, filtration by using the filter paper. It was derived by 2-aminobenzamide solution. The extracts were centrifuged and filtered by using the organic filter membrane and analyzed by using a AdvanceBio Glycan Map column to be separated and detected，employing acetonitrile-50 mmol/L ammonium formate solution （pH 4.4） as the mobile phase for gradient elution. Results: Under the experimental conditions, six human milk oligosaccharides in dairy product were linear in the range of 1.00～400.0 mg/L, and the correlation coefficients were all over 0.999. The detection limit of the method was 4.1～10.9 mg/kg, the limits of quantification were 12.3～32.7 mg/kg, the mean recoveries rate was ranged from 71.3% to 90.2% with the intra-day precisions （n=6） in the range of 1.0%～6.3% and inter-day precisions （n=6） less than 10.0%. Conclusion: This method can meet the requirements of the daily detection of six human milk oligosaccharides due to its simplicity and sensitives.

Abstract:Objective: To explore the differences in runner performance of screw groups with different differential ratios, and to clarify the effects of differential speed on the extrusion performance of polylactic acid materials. Methods: Four groups of differential twin screw groups were established by Solidworks software, meshing and finite element numerical simulation were carried out by Fluent software, the calculation results were analyzed by CFD-post software, and the contours and discounted plots of various characterization parameters were combined, and they were verified by experiments. Results: Under the condition that the inlet and outlet pressures were 0.2 MPa and 0.5 MPa, and the reference speed of a single head was 30 r/min, the screws with a differential ratio of 1∶2 and 1∶3 had their own advantages and disadvantages under different properties, and the screws with a difference ratio of 1∶2 for output and pressure in the barrel had an advantage. In terms of mixing capacity, a screw with a differential ratio of 1∶3 had an advantage. Conclusion: Compared with the traditional twin-screw extruder, the differential twin-screw extruder has a positive impact on the extrusion performance of polylactic acid materials, and can be used as a new polylactic acid production equipment.

Abstract:Objective: A trans-critical CO₂ refrigeration system with ejector is proposed and its performance factors are studied. Methods: In this paper, energy and exergic system model combined with experiment method were used to study the impact of the change of major parameters on traditional and new refrigeration systems. Results: In a given working condition, exergy efficiency of the compressor increased by 11.08% when an injector replaced the throttle valve, while the power of the compressor decreased by 6.04% and the performance factor increased by 11.1%. The optimum gas cooler pressure was found to maximize the system performance. In addition, the exergic damage of the system components was optimized in this paper. Conclusion: The ejector of the new system has great potential for optimization, and the outlet temperature of the gas cooler has the greatest influence on the performance of the ejector.

Abstract:Objective: To solve the problems of low control accuracy and poor motion stability in the trajectory tracking control method of parallel food sorting robots. Methods: On the basis of analyzing the structure of a four degree of freedom parallel robot, a combination of sliding mode control algorithm, fuzzy control algorithm, and improved bat algorithm was proposed for trajectory tracking control of a parallel food sorting robot. Optimizing the bandwidth of fuzzy algorithms by improving the bat algorithm, and adaptively adjusting the fuzzy gain and sliding surface slope of the sliding membrane control algorithm through the optimized fuzzy control algorithm, the tracking error of the controller was reduced, improve anti-interference ability, and verify the superiority of the proposed trajectory tracking control method. Results: The proposed trajectory tracking control method had an actual sorting accuracy of 99.90% and an average sorting time of 0.509 seconds. Conclusion: Compared with conventional methods, the proposed trajectory tracking control method has higher joint trajectory tracking accuracy, stronger anti-interference ability, and smoother output torque.

Abstract:Objective: To improve the accuracy and comprehensiveness of oyster grading. Methods: The oyster automatic grading equipment was proposed and designed, the oyster queuing structure combining the rotating drum and the baffle conveyor belt, the grading method combining weight detection and machine vision detection were determined, and the overall structure design of the oyster grading equipment was completed. The oyster image was collected by industrial camera, and the oyster image was extracted by Otsu binarization, Gaussian filtering processing, Canny operator edge extraction and other methods. The oyster was graded by machine vision algorithm with length and fullness as the standard, and the comparison test between machine vision grading and manual grading were carried out. Results: The machine vision classification accuracy of oysters was 95.4%, and the image detection speed was about 0.647 s/image. Conclusion: Machine vision is effective for oyster grading and can classify oysters more accurately.

Abstract:Objective: To solve the problems of low accuracy and low efficiency, high labor intensity and high production cost of fresh fruit manual sorting in China. Methods: A new dynamic weighing type fruit sorting machine was developed based on the fruit weight classification method. This machine operated by initially collecting the weight of fruit through a high-precision weighing unit. The data collected was then processed in conjunction with a signal processing module and a Programmable Logic Controller (PLC). The processed data controlled an actuator, specifically a launcher, to execute the sorting based on the fruit's weight. This machine was capable of continuously performing loading, weighing (diameter ≤126 mm). Results: When the separation efficiency was 18 327, 14 400, 10 473 PCS/h, the average separation accuracy was 95.31%, 96.12%, 97.13%, and the damage rate was 1.09%, 1.11%, 1.15%, respectively. Fruit sorting speed significantly affected the sorting accuracy, but had no significant effect on fruit damage rate. Conclusion: The new dynamic weighing type fruit sorting machine can effectively improve the efficiency of fruit sorting and reduce the damage to fruit under the premise of keeping the sorting accuracy >95%.

Abstract:Objective: Screening of polyvinyl alcohol-fish gelatin-solanum nigrum anthocyanin （PVA/FG-SNA） composite packaging film with optimal structure and properties. Methods: Optimizing the fabrication process of films through orthogonal tests, and using thickness, moisture content, water vapor permeability （WVP）, tensile strength （TS）, elongation at break （EB）, Fourier infrared spectroscopy （FTIR）, X-diffraction （XRD）, scanning electron microscopy （SEM）, and thermogravimetric （TG） analysis to explore the effects of SNAs with different mass fractions on the properties and microstructures of PVA-FG film; In addition, the pH color response and NH₃ sensitivity of the PVA/FG-SNA composite film were monitored. Results: When the mass ratio of PVA-to-FG, heating temperature and time were 60∶40, 95 ℃, and 1.5 h, respectively. The water solubility and WVP of the PVA-FG film were （36.03±2.63）%, and 2.91×10^-4 g·mm/（m²·h·Pa）, separately. With the increment of SNA dosage, the thickness, moisture content, WVP, and EB of the PVA-FG film also increased. When the mass fraction of SNA was 0.2%, the thickness, moisture content, WVP, TS, and EB of the composite film were （0.07±0.01） mm, （11.09±0.25）%, 5.45×10^-4 g·mm/（m²·h·Pa）, （21.12±1.07） MPa, and （373.77±8.59）%, respectively. At the same time the composite film had good compatibility among its components. In addition, the PVA/FG-0.2% SNA film showed good color response under NH₃ atmosphere conditions, which could be used as a pH-indicating film. Conclusion: This article optimized the water resistance of the PVA-FG composite base film. The hydrophobic and mechanical properties of the PVA-FG composite base film are negatively correlated with the amount of SNA dosage, and SNA can significantly enhance the pH and NH₃ sensitivity of the film.

Abstract:To meet the needs of consumers to combine traditional cultural connotations with food packaging, a research method for extracting traditional pattern features under extensible semantics is proposed. By analyzing and screening the patterns of Tang Dynasty gold and silver artifacts, the target pattern elements were established, and an extensible semantic model was constructed; Perform semantic lexical extension analysis on pattern primitives to obtain the maximum design value range. Visualize and analyze feature semantics using graphical thinking, and derive and evolve them using shape grammar. Taking a certain mooncake packaging design as an example, several design schemes were designed using this method, and fuzzy comprehensive evaluation was conducted on them, achieving high satisfaction. The feasibility and effectiveness of the design method based on extensible semantics have been verified, providing new ideas for the inheritance and development of traditional patterns in modern food packaging design.

Abstract:Integrating technological elements or showcasing technological features in food packaging design can present unique visual effects and functional value, enhancing product image and brand value. This paper further optimizes the presentation effect of technology in food packaging design and enhances the market competitiveness of products through clear design positioning, exploration of diverse expressions, integration of traditional culture, and reflection of humanistic care.

Abstract:Objective: A coupled model for predicting tomato quality during short-term storage and transportation under extreme temperatures, utilizing the Arrhenius equation in conjunction with meteorological temperature data, to forecast the quality changes in tomatoes during the short-term storage and transportation processes under extreme weather conditions. Methods: Analyzing the meteorological temperature data for the year 2020 in Weifang, Baoding, and Daxing, 7 temperature points were selected to simulate the range of temperature variations for short-term storage and transportation of tomatoes. By utilizing the Arrhenius equation and integrating temperature with weight loss rate, hardness, color difference (ΔE), and sensory evaluation scores (SE), a coupled model was developed for predicting tomato quality. The model was validated by using temperatures of -10 ℃ and 12 ℃. Results: Within 48 hours of storage and transportation, Loss rate and ΔE of tomatoes gradually increased, while evaluation scores (SE) and hardness decreased gradually. The quality prediction coupling model based on the Arrhenius equation combined with meteorological temperature data was constructed. Under storage conditions from 0 to 36 ℃, changes in loss rate and SE were fitted with zero-order reactions, while changes in hardness and ΔE were fitted with first-order and half-order reactions, respectively. For storage conditions from -15 to 0 ℃, zero-order reaction fits were applied to model the changes in SE, ΔE, weight loss rate, and hardness. Validation of the predictive model revealed that, under 12 ℃ storage conditions, the relative errors for tomato weight loss rate, hardness, and SE were within 15%, except for the 48 hour prediction. Under -10 ℃ storage conditions, the relative errors for tomato hardness and SE were within 15%, excluding the 48 hour prediction. Conclusion: The coupled model for tomato quality prediction, constructed by integrating the Arrhenius equation with extreme meteorological temperature data, proves to be effective in forecasting the quality of tomatoes under extreme temperature conditions.

Abstract:Objective: In order to improve the accuracy of machine vision technology in grading the appearance quality of red Fuji apples, a red Fuji apple appearance grading method based on improved whale optimization algorithm （WOA） and CNN is proposed. Methods: A red Fuji apple image database with different appearance quality levels was established, and the database images were preprocessed so as to improve the training effect and generalization ability of the model. The improved CNN-LSTM was designed as the weighted grey correlation method was used to compress the CNN convolution scale, in order to reduce redundant interference between features and improve the computational speed of the model. The improved whale optimization algorithm was used to optimize the hyperparameters configuration of CNN-LSTM, effectively reducing the impact of improper hyperparameter configuration on model classification results. Results: The simulation results showed that the proposed classification method had a higher accuracy, with classification accuracy and sensitivity improved by about 2.05% and 2.46%. Conclusion: The proposed method can effectively achieve the appearance grading of red Fuji apples.

Abstract:Objective: Improve the identification accuracy of banana ripeness. Methods: A novel method was established to identify banana ripeness based on CNN and XgBoost. Firstly, convolutional neural network was used to extract banana image features, and full-connected layer network and linear discriminant analysis were used to simplify banana image features. Then, the hyperparameters of the limit gradient lifting algorithm were optimized by Bayesian optimization algorithm. Finally, the simplified banana image features were input into the limit gradient lifting algorithm, and the banana ripeness was judged by the limit gradient lifting algorithm. Results: The identification accuracy of the method for banana ripeness was 91.25%. Compared with the existing methods, the proposed method was more accurate to distinguish the ripeness of bananas with small data volume. Conclusion: The proposed method can realize the accurate identification of banana ripeness, which is helpful for warehouse managers and exporters to monitor banana ripeness in real time.

Abstract:Objective: To mitigate unfavorable factors during the packing, transportation, and storage of fruits and vegetables, a foldable, preassembled turnover box was designed based on the premise of recycling. Methods: Standardized boxes were used to hold sweet potatoes, which were considered long rotating ellipsoids, and the storage environment was modeled. A porous medium model, a species transport model, and a local non-thermal equilibrium model were used to study the temperature, humidity, speed, O₂ volume fraction, and CO₂ volume fraction distributions in the cargo area during the curing warming, post-curing cooling, and storage stages. Results： 40 ℃ was the optimum curing air supply temperature, and the time required was 5.85 h. 10 m/s was the optimum post-curing cooling air supply speed, and the time required was 8.47 h. The air supply velocity （4.0~6.0 m/s） had little effect on the distribution of O₂ and CO₂ volume fractions. When the air supply velocity was 4.5 m/s, the storage effect was the optimal, with deviation rates of 1.24% and 0.48% compared to the target storage conditions （12 ℃, 90.00% RH）. The generation of respiratory heat in sweet potatoes leaded to a shorter time for the internal temperature of the cargo area to reach the target curing temperature, while requiring a longer time to reach the target storage temperature. Compared to thermal conduction, convective heat transfer played a dominant role, resulting in a lag in temperature change between the internal and external temperatures of the cargo area during the storage process. Increasing the temperature and air supply velocity facilitated a faster attainment of the desired curing and storage temperatures. The physical characteristics and storage volume of sweet potatoes within the cargo area determined the subsequent warming and cooling processes. Conclusion: The velocity field on the surface of the cargo area exhibits a weak correlation with the distribution of RH, whereas the temperature field demonstrates a negative correlation with the RH field and exhibits a similar distribution pattern. The air supply velocity can alter the fluid flow direction inside the cargo area box, and both the magnitude of the air supply velocity and the direction of fluid flow inside the box significantly impact on the temperature distribution within the cargo area.

Abstract:Objective: The PCSPHs were prepared by enzymatic hydrolysis of Procambarus clarkii shells, and their hypoglycemic and lipid-lowering activities in vitro were evaluated and peptide sequence were analyzed. Methods: Different crayfish shell proteolysates were prepared by hydrolysis of pepsin, alcalase protease, trypsin, flavor protease and papain, and their in vitro hypoglycemic and lipid-lowering activities were evaluated and peptide sequences were determined. The peptides sequence of Procambarus clarkii shells was identified by LC-MS/MS. Taking the crystal structure of the nuclear receptor PPARγ ligand binding region as the target, Autodock vina was used to simulate molecular docking to obtain crayfish shell peptides with potential hypoglycemic/lipid-lowering activities. Results: The PEP-PCSPHs had significant inhibitory effects on α-amylase and α-glucosidase activity, with IC₅₀ values of （5.42±0.05） mg/mL and （7.11±1.01） mg/mL, respectively. The TRY-PCSPHs had the strongest inhibitory effect on pancreatic lipase activity, with an IC₅₀ of （4.71±1.12） mg/mL, and exhibited the best in vitro binding effects on sodium glycinocholate. In addition, 3 391 peptide sequences were identified in pepsin hydrolysates and 2 086 peptide sequences were identified in trypsin hydrolysates, and multiple hypoglycemic/lipid-lowering crayfish shell active peptides that could bind to PPARγ were screened through online website prediction and molecular docking. Conclusion: The shrimp shell peptides prepared by enzymatic hydrolysis of crayfish shells have potential hypoglycemic and lipid-lowering activities, which may play a role in improving glucose and lipid metabolism disorders.

Abstract:Objective: This study aimed to investigate the nutrient composition and the optimal enzymatic conditions for the peptides of Aspongopus and lay the groundwork for the creation of Aspongopus protein resources. Methods: The fat, protein, crude polysaccharide content, and fatty acid composition were determined according to the national standard method, and the total flavonoid and polyphenol content was determined by the standard curve method. Response surface methodology was used to optimize the enzymatic process conditions of Aspongopus based on the peptide yield; Amino acid analyzer and high-performance gel permeation chromatography was used to determine the amino acid composition and the relative molecular mass distribution of Aspongopus digest; The scavenging ability of Aspongopus digest of DPPH radicals and ABTS⁺ radicals as well as the total reducing ability were investigated. Results: Aspongopus crude fat content was 43.40%, and protein content was 37.08%; The contents of total sugar, total flavonoids and total phenols were 7.64%, 1.67%, 1.90% respectively; The optimum enzymatic digestion process of Aspongopus was stewing for 5 h and then digesting for was 6 h at pH 10 and 55 ℃, and the peptide yield was 35.74% under these conditions. The ratio of essential amino acids to non-essential amino acids of Aspongopus digest was 70.46%, the percentage of Aspongopus digest relative molecular mass <1 000 was 88.1%; The ABTS⁺ clearance rate was 88.44% at the concentration of 1.0 mg/mL of the enzymatic digest of Aspongopus. Conclusion: Under the control of the optimal procession conditions, the peptide yield of Aspongopus was 35.74%, with high nutritional value and good antioxidant activity.

Abstract:Objective: To discover the material substances of the numbing characteristics in Polygonatum Rhizoma. Methods: Polygonati Rhizoma from eight regions were processed by the "nine-steam-nine-bask" method, and its content changes of saponin, polyphenol and calcium oxalate crystal at different steaming times were determined. The degree change of numbing was determined by the cell hemolysis test and sensory properties, and a correlation analysis of numbing was conducted. Results: With the increase of steaming times, the contents of polyphenol and saponin in Polygonati Rhizoma from different regions were initially increased and then decreased, while the content of calcium oxalate crystal and hemolysis rate and the sensory score of numbing decreased gradually. The correlation analysis results indicated that there was a significant positive correlation (P＜0.05) or a highly significant positive correlation (P＜0.01) between the content of calcium oxalate crystal and the numbing degree. SEM results showed that the structure of calcium oxalate crystal was gradually destroyed after steaming, which coincided with the change of numbing. Conclusion: This research proves that calcium oxalate crystal may be the key substance for the numbing in Polygonatum Rhizoma, which can provide a scientific basis for the study of the numbing elimination technology of Polygonatum Rhizoma.

Abstract:Objective: To better control the growth of spoilage microorganisms, and ensure the food safety of Xiangwei Luodou dry. Methods: The putrefactive microorganisms in Xiangwei dried tofu were identified by plate scribing method, colony morphology observation, Gram staining, 16S rDNA and ITS sequence. Results: A total of 9 strains were isolated andscreened. KZ2780-3 and KZ2780-4 are Bacillus subtilis, NZ2559-1 is Bacillus cereus, and JZ2559-5 is Bacillusamylolyticus amyloliquefaciens, FZ2559-2 for Klebsiella pneumoniae, SZ2641-5 for Enterococcus faecium, RZ2641-7 for Staphylococcus haemolyticus, BZ2780-1 for Acinetobacter baui, CZ2780-5 for Penicillium citri. Conclusion: The strains causing dry rot of Xiangwei bean are Bacillus subtilis, Bacillus cereus, Bacillus amyloliquefaciens, Klebsiella pneumoniae, Enterococcus faecium, Staphylococcus hemolyticus, Acinetobacter baui and Penicillium citri. The control methods of Xiangwei stewed bean dry are ultra-high temperature instantaneous sterilization technology, plasma sterilization technology, natural antibacterial substances combined with biological preservatives, vacuum packaging, air conditioning preservation and so on.

Abstract:Objective: In order to predict and control the hot air drying process of Mango. Methods: Using fresh Mangifera indica Linn as experimental material, the effects were studied in different hot air temperatures (60, 65, 70 ℃) and different thickness of Mango slices (0.8, 1.0, 1.2 cm) on the drying curve, drying characteristic curve and effective moisture diffusion coefficient of Mango. Selecting six commonly used drying models suitable for fruits and vegetables for fitting, analysis, and validation, the most suitable model for Mango hot air drying was selected. Results: With the increase of temperature and the decrease of slice thickness, the drying rate of Mango slices was accelerated, resulting in shorter drying times. The effective diffusion coefficient of water increases with the increase of temperature and thickness, in the range of 1.401 39×10^-10 to 3.655 46×10^-10 m²/s. R² of Logarithmic model was the largest, and X² and RMSE were the smallest, which were 0.998 87, 0.000 124 779 and 0.001 37 respectively. Conclusion: The predicted values are basically consistent with the experimental values, accord with Mango hot air drying, it can better reflect the changing law of moisture content of Mango slices during drying.

Abstract:Objective: This study aimed to optimize the preparation process of polysaccharides from lemon peel and screen out the components with high hypoglycemic activity. Methods: Ultrasonic assisted enzymatic extraction of lemon peel polysaccharide, combined with response surface test to explore the best extraction process, through DEAE-52 anion chromatography and Sephadex G-100 gel column chromatography separation and purification to obtain a homogeneous polysaccharide fraction (named as LPs-1a). The effective hypoglycemic components of lemon peel polysaccharides were screened by α-glucosidase and their relative molecular weight, monosaccharide composition and characteristic groups were analyzed. Results: The optimal extraction process of lemon peel polysaccharide was ultrasonic treatment for at 55 ℃ for 44 min with solid-liquid ratio 1∶20 (g/mL) and cellulase addition rate 1.1%. Under the control of these conditions, the yield of lemon peel polysaccharide was 6.83%, which was close to the predicted value. The LPs-1a fraction significantly inhibited the activity of α-glucosidase with （1.22±0.04） mg/mL of IC₅₀(P＜0.05). The relative molecular weight of this component was 195 260, and it was connected by α-glycosidic bonds and β-glycosidic bonds with a pyranose ring. The morphology of the polysaccharide was fibrous, and it was composed of mannose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose and arabinose Conclusion: Ultrasound-assisted enzymatic method is helpful in screening the highly hypoglycemic active components of lemon peel polysaccharides.

Abstract:Objective: Determine the appropriate soymilk concentration and slurry depth to provide a theoretical reference for the efficient and high-quality production of yuba. Methods: The effect of soymilk solids concentration and slurry depth on the yield, film-forming rate, nutrient contents, mechanical properties, cooking loss rate, and rehydration ratio were investigated. Results: The optimal yield solids of yuba (34.68%) and highest nutritional value occurs when the soymilk solids concentration is 6% and the soymilk slurry depth is 6 cm, which presents 51.05% protein, 23.42% fats, and it also has good tensile strength and rehydration qualities, with respective measurements of 3.74 MPa and 3.80 g/g. Conclusion: Considering various factors such as yield, film formation rate and overall food quality, it is recommended to employ processing conditions with a soymilk solids concentration of 6% and a slurry depth of 6 cm for the efficient and high-quality production of yuba.

Abstract:Objective: This study aimed to prepare a kind of mushroom paste with Lentinus edodes, Pleurotus eryngii and Agaricus bisporus as raw materials by enzymolysis with cellulase. Methods: The response surface method was used to optimize the optimal enzymatic hydrolysis process of the mushroom paste with amino acid nitrogen content as the index. Results: The optimal enzymolysis conditions were as follows: enzyme dosage 0.6%, pH 6, enzymolysis temperature 50 ℃, solid-liquid ratio 1∶30 （g/mL）. Under these conditions, the actual amino acid nitrogen content was 0.418 μg/100 g. Conclusion: The sensory evaluation and nutritional indexes of the mushroom paste are up to or better than the national standard, which indicates that the process is feasible and has certain popularization and application values.

Abstract:As one of the most widely used plasticizers, BPA is often used in various types of food packaging. However, the leaching of BPA from food and water and the emission of BPA in the manufacturing process can harm human health. In recent years, carbon-based composites have shown excellent performance in the detection of BPA due to their unique physical and chemical properties. The rapid detection of BPA by electrochemical sensors based on carbon-based composites has become a research hotspot. This article provides an overview of BPA and the application of carbon-based materials modified electrochemical sensors in the detection of BPA, as well as prospects for the development direction of electrochemical detection of BPA.

Abstract:Because of high moisture content, blueberries are susceptible to disease and insect infestation leading to corruption and deterioration, which has serious influence on the shelf life of blueberry fruits. This article summarizes the cause mechanism of postharvest quality deterioration of blueberry fruits and the research progress of blueberry preservation technology at home and abroad, mainly including physical, chemical and biological preservation methods; and emphasizes the application of biological methods in the postharvest preservation of blueberries.

Abstract:Polysaccharides and proteins are two important components in food. Combining plant protein with polysaccharides can give full play to their advantages, show new functional characteristics, and improve their shortcomings. In this review, the preparation and influencing factors of polysaccharides-plant proteins complex, the functional properties of the polysaccharide-plant protein complex and its application are introduced.

Abstract:Nanomaterials have been widely used in the detection of heavy metal ions in food due to their large specific surface area, good stability, special structure, easy modification, and good biocompatibility. This review focuses on the research and application status of nanomaterials such as carbon nanotubes, graphene, carbon quantum dots, metal-organic frameworks and nanoenzymes in the detection of heavy metal ions in food. The challenges and application prospects of nanomaterials in the detection of heavy metal ions in food are also discussed.