Abstract:Objective: This study aimed to investigate the differences in enzymatic properties of endogenous transglutaminase （TGase） in silver carp and black carp. Methods: STG and BTG were purified from the muscle of silver carp and black carp, respectively, by 80% ammonium sulfate precipitation, Q-Sepharose FF, and Sephacryl S-200 HR chromatographies. Two enzymes were analyzed for relative molecular weights, peptide sequences, secondary structures, optimal reaction conditions, and thermal inactivation kinetics. Results: The purified STG and BTG showed similar relative molecular weights, of which the enzyme activities were 14.34 U/mg and 12.67 U/mg, respectively. Both enzymes showed differences in peptide sequences. The secondary structures of them were mainly the β-fold, though the content of β-fold in STG was slightly higher than that of BTG. The optimal temperatures for STG and BTG were both 50 ℃, and the optimal pH values were 8.0 and 7.5, respectively. The enzymes required Ca²⁺ up to 1 mmol/L for full activation. The activities of STG and BTG were enhanced by DTT, whereas PMSF, NH₄Cl, NEM, EDTA, Cu²⁺, Ba²⁺, Zn²⁺, and Mg²⁺ showed inhibitory effects. When the temperature was 37~50 ℃, the passivations of STG and BTG by thermal treatment conformed to the first-order exponential decay kinetics with similar values of E_a. Conclusion: The primary and secondary structures of STG and BTG exhibited obvious differences, yet they still exhibited similar properties in terms of optimal reaction conditions and thermal inactivation kinetics.

Abstract:Objective: To screen Bifidobacterium from breast milk and improve its oxygen tolerance under aerobic conditions. Methods: Dilution and spread plate methods were performed to separate and screen Bifidobacterium from breast milk. Their Bifidobacterium identifications were characterized by 16S rDNA sequencing. The oxygen tolerant domestications were conducted through gradual increase of oxygen pressure and alternation of aerobic and anaerobic cultivations. Results: A novel Bifidobacterium strain was isolated from human milk and was identified as Bifidobacterium longum by 16S rDNA sequencing, which was named as MEFZ-2201. The homology between MEFZ-2201 and model strain (accession number in NCBI: ON631733.1) reached 100%. After oxygen tolerant domestication, the highest viable bacteria number of Bifidobacterium longum MEFZ-2201d in aerobic cultivation reached 8.9×10⁹ CFU/mL, which was ten times higher than that of its wild-type strain MEFZ-2201. Whereas, the morphological property and physio-biochemical characteristics of Bifidobacterium longum MEFZ-2201d did not change after oxygen tolerant domestication. The short-chain fatty acid production of domesticated strain Bifidobacterium longum MEFZ-2201d was also significantly higher than that of its wild-type strain even under anaerobic conditions. Conclusion: A novel Bifidobacterium longum strain MEFZ-2201 was isolated from breast milk. The viable bacterium number of its domesticated strain MEFZ-2201d was significantly increased under aerobic conditions, indicating that it would be a potential probiotic strain for further development and utilization.

Abstract:Objective: This study aimed to investigate the effects of different processing temperature on texture profile and flavor of dried edible bird's nest. Methods: With dried edible bird's nest as the main raw material, the texture profile analysis of edible bird's nest at different processing temperature was carried out by physical property analyzer. The volatile components of edible bird's nest at different processing temperature were determined by electronic nose and solid phase microextraction gas chromatography-mass spectrometry (SPME-GC-MS). Results: It was found that the adhesion of cooked edible bird's nest decreased significantly (P<0.01), but its resilience increased significantly (P<0.05) with the increase of temperature. 12 kinds of effective flavor substances were detected in the cooked edible bird's nest by SPME-GC-MS, including: 3 alcohols, 2 aldehydes, 2 esters, 3 ketones, 1 acid, and 1 ether, accounting for 6.23%, 49.34%, and 54.85% of the total detected substances in the cooked edible bird's nest at 95 ℃, 105 ℃ and 115 ℃, respectively. Conclusion: Different processing temperature affects the taste of edible bird's nest and the overall odor profile after processing. Moreover, higher cooking temperature tends to make the egg white-like flavor stronger. The volatile substances in the bird's nest stew at 95 ℃ are mainly acids, the bird's nest cooked at 105 ℃ mainly produces alcohols, and the edible bird's nest cooked at 115 ℃ mainly produces ketones and alcohols.

Abstract:Objective: This study aimed to investigate the varieties and contents of volatile components in fermented dough with flavor fermentation broth at different fermentation time. Methods: Headspace solid phase microextraction-gas chromatography (HS-SPME-GC-MS) was used to determine the volatile flavor substances in the dough of the flavor ferment at 12, 24, 36, 48 and 72 h. Also, sensory evaluation of the odor and determination of pH value, total acidity (TAA) and rheological properties of the dough were measured. Results: The strength of eight odors (frankincense, cheese, flower, fruit sweet, wine, malt, grass and sour) showed different performance, depending on the types and contents of the flavour substances produced during the different fermentation periods. The pH value of the dough gradually decreases with the time of fermentation, while TTA was the opposite. The tensile resistance, stretch ratio and tensile area of dough increased first but decreased with the extension of fermentation time, while the elongation of dough decreased first then increased. These results indicated that moderate fermentation (36 h) was beneficial to the formation and stability of the gluten network. A total of 92 volatile substances were detected in the dough with 5 fermentation times, including 22 alcohols, 27 esters, 12 aldehydes, 14 ketones, 10 alkanes, and 7 acids. A total of 27, 43, 38, 41 and 37 volatile flavor components were detected from the dough fermented for 12, 24, 36, 48 and 72 h, respectively. The contents of acids and esters increased first then decreased with the prolongation of fermentation time and reaching the highest at 48 h (47.31% and 20.96%, respectively). On the other hand, the contents of aldehydes, ketones and acids all gradually decreased. Conclusion: The volatile substances of different fermentation times were alcohols mainly, and the total flavor substances and the relative content of alcohols and esters reached the highest at 48 h, indicating that alcohols and esters might be the major contributors to the flavor of dough during fermentation.

Abstract:Objective: To investigate the best defrosting method for frozen pork. Methods: Investigated the effects of three thawing methods, namely low-frequency electric field thawing, air thawing and hydrostatic thawing, on the juice loss rate, moisture content, water holding capacity, pH, colour difference, volatile saline nitrogen, total bacterial colony, textural characteristics, fat oxidation and protein oxidation of pork after thawing. Results: The low frequency electric field thawing resulted lower juice loss (1.09%), shear force (2 600.15 N), increase in thiobarbituric acid value (TBARS) (62.50%), good colour, pH close to that of fresh meat, less protein oxidation, richer taste material, less damage to the microstructure of the meat, better maintenance of muscle tissue and muscle fibre structure. The hydrostatic thawing resulted lower total bacterial colony count and llow protein oxidation. Conclusion: The quality, physicochemical properties and microstructure of pork under low frequency electric field thawing were better than the other two thawing methods.

Abstract:Objective: The purpose of this study was to investigate the drying characteristics and establish the kinetic model of Antarctic krill during spin-flash drying. The drying experiments were carried out at 120 ℃ to 180 ℃. Methods: Six common thin-layer drying models were selected to fit the experimental data. Further, the equations of drying model constant and temperature were established to obtain the model expression and validate the optimal drying model. The effective moisture diffusion coefficients were calculated by Fick's second law. Results: The results showed the drying temperature had a significant effect on drying thermal efficiency and drying rate. The spin-flash drying of Antarctic krill was a falling rate drying process at 130 ℃ to 180 ℃. The Page model was suitable for describing and predicting the spin-flash drying process of Antarctic krill. The constant term equations of the model were established by regression analysis, which were k=exp（－27.532 1＋0.301 8T－8.538 2×10^-4T²）and n=14.010 6－0.157 67T＋4.750 9×10^-4T². As the drying temperature increasing, the effective moisture diffusion coefficient increased from 2.539 35×10^-7 m²/s to 13.889 64×10^-7 m²/s. Conclusion: The spin-flash drying method had the advantages of higher effective moisture diffusion coefficient and higher drying efficiency, which can effectively protect the thermal sensitive composition in Antarctic krill from being damaged and improve the product quality.

Abstract:Objective: This study aimed to establish a method for the Preparation of matrix reference material for carbaryl residues in Chinese yam flour. Methods: Yam powder containing menafyl was prepared by homogenized, freeze-dried, ground, sifted, mixed and packaged. A liquid chromatography-series mass spectrometer was used for detection, and the isotope internal standard curve method was used for quantification. Through the process of equalization stability evaluation, cooperative setting and uncertainty evaluation, the matrix reference material of the expected yam powder was obtained. Results: The property value and expanded uncertainty of carbaryl was (1.04±0.10) mg/kg (k=2). Conclusion: It could be used for food laboratory method verification, quality control and other activities.

Abstract:Objective： A rapid method was established for the simultaneous determination of variety anions in liquid milk. Methods： The macromolecular protein in liquid milk was precipitated by acetonitrile, and a variety of anions were extracted. After purification by C₁₈ column, the material was separated by Dionex IonPac AS19-HC ion column with gradient elution of potassium hydroxide and conductivity detection. Finally, a method for the determination of bromate, thiocyanate, nitrite, nitrate, chlorate, perchlorate, phosphate and iodine ion in liquid milk was established using ion chromatograph. Results： The results showed that the correlation coefficients （R²）of eight kinds of anion range from 0.999 0 to 0.999 8 in the linear range, and the limits of detection were between 0.065 mg/kg and 0.417 mg/kg. The recoveries were in the range 81.8%～102.0% with the relative standard deviations in the range 1.1%～6.7%（n=6）. Conclusion： The method has the advantages of simple operation, high accuracy and sensitivity, and can be used for simultaneous determination of various anion residues in liquid milk.

Abstract:Objective: To explore the content of aldehydes in Baijiu. Methods: A method for the determination of 17 aldehydes in Baijiu was established, and the methodological performance indexes were studied using statistics. Results: Through statistical analysis, the detection limit of 17 aldehydes in Baijiu was determined to be 0.7～5.9 mg/L, the limit of quantification was 1.9～14.6 mg/L, which passes the quality inspection of the calibration curve within the range of 0.6～320.0 mg/L, and the linear relationship meets the requirements. The recovery rate of intermediate standard addition in Baijiu was 73%～114%, the coefficient of variation in the laboratory was ≤11%, and the accuracy deviation range was -18.7%～8.0%. Conclusion: The method can be used for the determination of various aldehydes in Baijiu.

Abstract:Objective: To establish a new accurate method for the determination of mineral oil saturated hydrocarbon （MOSH） in infant formula by solid phase extraction combined with gas chromatography-Flame Ionization Detection （SPE-GC-FID）. Methods: Different extraction methods such as soaking extraction, oscillating extraction, ultrasonic assisted extraction, liquid-liquid extraction were used to extract MOSH from infant formula milk powder, and different extraction solvents such as n-hexane, isooctane, benzene, mixed solvents were used to extract MOSH. The optimal extraction method and extraction solvent were determined based on the extraction amount of MOSH. The target compounds purified by AgNO₃ SPE column, and finally detected by gas chromatography-Flame Ionization Detection （GC-FID）. Results: The calibration curve of MOSH was linear in the range of 10.0～1 000 μg/mL with correlation coefficient of 0.999 97. The limit of detection was 1.0 mg/kg, and the limit of quantitation was 3.0 mg/kg. The recoveries from spiked samples were 93.3%～103.7%, and the relative standard deviations were 2.3%～5.9%. The MOSH in 8 commercially available infant formula was detected by the established method, and the results were between 1.06 and 9.83 mg/kg, indicating that there was a certain risk of MOSH contamination in infant formula. Conclusion: This method is accurate, sensitive, and suitable for the detection of MOSH in infant formula.

Abstract:Objective： An ultra performance liquid chromatography-quadrupole/time-of-flight mass spectrometry （UPLC-Q-TOF/MS） method was established for the determination of abietic acids in poultry. Methods： The samples were extracted with acetonitrile, then salted out and stratified. The supernatant was purified by C₁₈ solid phase extractant and finally determined by UPLC-Q-TOF/MS in ESI negative mode. Results： Abietic acid compounds exhibited a good linear relationship in the concentration range of 10~500 μg/L with good correlation coefficient R²>0.998. The average recoveries of three abietic acid compounds were experiments, the average recovery rate was 87.8%~98.5% with relative standard deviations （RSDs, n=6） of 1.99%~6.71%, at the spiked level of 20, 40, 200 μg/kg. The limits of detection （LODs） were 10 μg/kg and the method limits of quantification （LOQs） were 20 μg/kg. Conclusion： This method was convenient operation, rapid, high recovery and sensitivity and good precision that could meet the determination requirements of three abietic acids in poultry.

Abstract:Objective: A new technical idea was provided for the study of biogenic amine formation mechanism and food safety risk assessment. Methods: An analytical method was established for determination of tyramine, phenylethylamine, tryptamine, octopamine and cadaverine in cheeses with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Biogenic amines were extracted by ultrasonic-assisted solvent extraction from cheeses, and were separated by HILIC column, determined by positive electrospray ionization (ESI) with multiple reaction monitoring (MRM) mode, quantified by the internal standard method. The effect of extraction solvent type, ultrasonic time and matrix effect on the peak area was studied, and the performance of the method was validated and evaluated. Results: Using 0.1% formic acid (acetonitrile/water) as the extraction solvent, the samples were extracted by ultrasound for 15 min. Ammonium acetate of 5 mmol/L (pH value was adjusted to 4 by formic acid) and acetonitrile were used as the mobile phase，biogenic amines without derivatization were detected by HPLC-MS/MS. The recoveries of 5 biogenic amines were 78.6%～113.8% and relative standard deviations were 2.41%～7.12% at three spiked levels. The limit of detection of tryptamine, phenylethylamine, tyramine and octopamine was 0.75 μg/kg and the limit of quantification was 2.5 μg/kg; The limit of detection of cadaverine was 1.50 μg/kg and the limit of quantification was 5.0 μg/kg. The linear relationship was good in the respective linear ranges, and the correlation coefficient was greater than 0.99. The method was used for the determination of commercially available cheese samples. The contents of different biogenic amines in different samples varied greatly, ranging from 4.45 to 2 863.00 μg/kg, which was within the safe range. Conclusion: The proposed method was suitable for fast determination of 5 kinds of biogenic amines in cheese.

Abstract:Objective: Analyzed the influencing factors of the internal flow field pulsation characteristics of the new double circular arc gear pump, and adopt reasonable parameters to improve the output efficiency of the gear pump. Methods: The two-dimensional flow field simulation model of the gear pump was established, and the computational fluid dynamics software Fluent was used for simulation analysis to study the influence of different tip clearance, different gear eccentricity, load and speed on the instantaneous flow, flow pulsation and flow field characteristics of the oil outlet of the gear pump. Results: As the tooth tip clearance increased, the outlet flow rate of the gear pump gradually decreased. When the tooth tip clearance was 0.09 mm, the minimum pulsation coefficient of the outlet flow rate was 0.135, which was the optimal tooth tip clearance for the gear pump under this structural parameter. Due to the influence of load pressure and rotational speed, the central axis of the gear pump deviates. As the eccentricity of the central axis of the gear pump rotor increased, the outlet flow rate of the gear pump gradually increased. When the eccentricity was 0.05 mm, the outlet flow rate of the gear pump increased by 5.09% compared to without central deviation, improving the flow output. Conclusion: The main influencing factors on the flow characteristics of gear pumps are rotor speed and tooth tip clearance, and the influence of center deviation is relatively small.

Abstract:Objective: Taking polylactic acid （PLA） as an example, the flow channel distribution of twin-screw extrusion under different pitch was studied. Methods: In Solidworks, two 3D models with variable pitch and constant pitch were drawn according to the theoretical end curve equation and modified. Workbench software was used to generate the required analysis models with the swept mesh method for the two screw configurations, and then Polyflow fluid simulation software was used to simulate the actual situation. After obtaining the post-processing results, FieldView software was used to analyze the final results. The pressure, shear rate and viscosity of polylactic acid fluid under simulated conditions were studied. Meanwhile, the residence time distribution curve RTD was analyzed by Polystat statistical module. Results: Under the same conditions, the pressure, shear rate and viscosity fluctuation of the screw with variable pitch increased, and the axial mixing performance improved, but the self-cleaning ability decreased. Conclusion: The change of pitch has a certain effect on polylactic acid, but too large change of pitch often produces adverse effects. Therefore, it is necessary to design suitable variable pitch screw according to the actual situation to improve the yield and quality.

Abstract:Objective: To improve the energy efficiency of mango drying in the air source heat pump system so as to save energy. Methods: The process of drying mangoes was subdivided, and a variable structure control was used to adjust the temperature and humidity of drying room intelligently and dynamically to improve energy efficiency. Each drying process stage was divided into three parts, namely far away from the conversion point, near the conversion point, and closing to the conversion point. For the first two parts, a constrained nonlinear autoregressive neural network (NARX) with external inputs was used to intelligently adjust the temperature and humidity settings so as to save electricity, while for the third part, a PI controller was used to accurately control the dehumidification amount at the conversion point of the drying process so as to ensure the quality of mango drying. Results: Compared with conventional segmented constant temperature and humidity drying methods, the proposed control method could save 8.63% of electricity with a guaranteed quality of mango drying. Conclusion: The proposed subdivided variable structure control method can significantly improve the energy efficiency of heat pump drying systems, and achieve drying quality similar to conventional segmented constant temperature and humidity methods.

Abstract:Objective: Solved the problems of poor motion stability and accuracy in the food sorting process of parallel robots. Methods: Based on the analysis of the three degree of freedom food sorting robot system, a method proposed which combined polynomial interpolation and improve multi-objective particle swarm optimization algorithm for Delta robot trajectory optimization. As a parallel robot, the optimization of the shortest operation time, lowest energy consumption, and minimal motion impact were taken as multiple objectives. The improved multi-objective particle swarm optimization algorithm was applied to optimize the polynomial interpolation method, and its performance was validated. Results: The planning trajectory of the proposed planning method in the experiment was smoother and more efficient compared to conventional methods. In the actual selection of Camellia oleifera fruits, the accuracy was >99.00%, and the average screening time was 0.620 s. Conclusion: The trajectory planning optimization method proposed in the experiment has improved the sorting efficiency, accuracy, and stability of the Camellia oleifera fruit sorting robot.

Abstract:Objective: This study aimed to develop a green and environment-friendly sodium alginate/starch/tea powder composite membrane. Methods: Tea polysaccharides with different mass fractions were added to the sodium alginate/starch/tea powder composite film to investigate the influence of tea polysaccharides on the properties of sodium alginate/starch/tea powder composite film. Therefore, full infrared barrier, color difference, water solubility, water vapor permeability, tensile strength, elongation at break, thickness, water content, free radical clearance and bacteriostasis were measured. Results: A strong interaction between tea polysaccharides and sodium alginate were found. The composite film with tea polysaccharide content of 5% exhibited the best comprehensive performance. The best bacteriostatic performance was observed when the tensile strength, elongation at break, water vapor permeability were 9.71 MPa, 25.42%, and 2.38×10^-9 g瘙簚mm/(cm²瘙簚d瘙簚Pa), respectively. The antioxidant activity of the composite membrane increased with the increase of the amount of tea polysaccharide added, with a maximum of 85.49%. Conclusion: Tea polysaccharides can improve physicochemical properties, antibacterial and antioxidant properties of the composite membrane. When the mass fraction of tea polysaccharides was 5.00%, the composite membrane had the best mechanical, moisture, and antibacterial properties.

Abstract:In this review, the Meishan culture was investigated, and the Meishan Nuo facial makeup culture was found to be a unique cultural form predominantly native with a diverse coexistence. The distinctive artistic features and cultural connotations of this culture were highlighted. The cultural elements of the primitive, exaggerated, and humorous artistic design techniques were incorporated into the design of the public brand "Meishan Hui" for the local specialty foods in Xinhua. The brand design strategy, from visual to connotative expression, was analyzed by investigating the application of packaging of various local specialty food in Xinhua through case studies, and the design techniques of regional characteristics and folk culture in local characteristic food packaging were also demonstrated.

Abstract:Objective: To propose a new solution to overcome the two challenges of data with spikes and small sample sizes in nectarine hyperspectral measurement. Methods: Based on hyperspectral imaging technology, image processing methods were used to identify the area of nectarines in the hyperspectral image, and the spectral reflectance data of the area was calculated to form a hyperspectral curve image. For hyperspectral image data with spikes and noise, compared the effects of several data preprocessing methods, including polynomial smoothing algorithm (SG), multivariate scatter correction algorithm (MSC), standard normal variate algorithm (SNV), first-order derivative operator (D1), and second-order derivative operator (D2) on model prediction accuracy. To address the high-dimensional and small sample size characteristics of the data, the principal component analysis algorithm (PCA) was used for dimensionality reduction, followed by outlier removal using the Mahalanobis distance measure method (MD). Finally, the Kennard-Stone algorithm (KS) was used to divide the data into training and testing sets, and the partial least squares regression (PLSR) model, which performed well in the small sample scenario, was selected for estimation and analysis of nectarine water content. Results: The SG-PCA-MD-KS-PLSR model performed best for estimating nectarine water content when there were spikes and noise in the hyperspectral curve. The coefficient of determination (R²) was 0.928, and the root mean square error (RMSE) was 0.008 4 on the training set. The R² was 0.926, and the RMSE was 0.009 2 on the testing set. In further experiments grading nectarines based on their water content, the model's predictions showed good performance. The accuracy rate of grading was 0.956 for the training set and 0.923 for the testing set. Conclusion: By using hyperspectral imaging technology and establishing the SG-PCA-MD-KS-PLSR model, non-destructive estimation of nectarine water content and grading of nectarine water content can be achieved in scenarios with small hyperspectral sample sizes and noise.

Abstract:Objective: To improve the classification accuracy of strawberries. Methods: A method of strawberry classification based on improved CNN was proposed by improving CNN through mixing pool method. Firstly, through the combination of maximum pooling and average pooling techniques, a hybrid pooling method was obtained. Then, the hybrid pool method was used to improve the generalization ability of CNN model. After that, image data acquisition, image preprocessing and image feature extraction were carried out. Finally, sensitivity, specificity, accuracy, recall rate and F₁ score were used to evaluate the effectiveness of the trained strawberry classification method. Results: The sensitivity, specificity, accuracy, recall rate and F₁ score of the proposed method for strawberry classification in 16 pixel×16 pixel images reached 0.993, 0.993, 0.994, 0.992 and 0.991, respectively. Compared with the other five classification methods, the sensitivity, specificity, accuracy, recall rate and F₁ score of the proposed method were improved by 3.44%, 3.96%, 4.26%, 3.92% and 4.08%, respectively. Conclusion: This method can achieve accurate classification of strawberries with different maturity, and is expected to provide technical support for the research and development of high-performance strawberry packaging robots and supermarket fruit automatic recognition machines.

Abstract:Objective: In order to improve the precision of apple grade judgment model, the method of apple grade judgment was established. Methods: A decision model of apple rank based on multi-information fusion and dragonfly algorithm was proposed. Firstly, the HSV color feature, LBP texture feature and HOG shape feature of apple image were extracted by pre-processing such as data enhancement, normalization, Gauss filter and grayscale. Secondly, the performance of DBN model was affected by the selection of parameters, the network parameters of DBN model were optimized by DA algorithm, and a multi-information fusion and DA-DBN model for determining apple rank wws proposed. Results: Compared with GA-DBN, PSO-DBN, GWO-DBN and DBN, the model based on DA-DBN had the highest precision. Conclusion: The DBN model is optimized by dragonfly algorithm which can effectively improve the accuracy of apple rank determination model, which provides a new method for apple rank determination.

Abstract:Objective: This study aimed to screen potato varieties suitable for cultivation in southern Xinjiang. Methods: By combining factor analysis and cluster analysis, a comprehensive evaluation of the nutritional quality of 12 kinds of introduced potato species was conducted using them as test materials. Results: S1 contained the most protein, and S5 included the most soluble sugar content and vitamin C; S12 contained the least nitrate, and S10 contained the most reduced sugar and starch. Nutritional quality indicators differ significantly among potato varieties. The coefficients of variation of soluble sugar content, vitamin C content, and nitrate content were 47.13%, 37.03% and 33.38%, respectively. The two primary components identified by factor analysis were the protein content and vitamin C content, and the potato quality was further divided into 3 clusters using systematic cluster analysis. Conclusion: The five varieties S1, S5, S7, S10 and S11 are suitable for promotion in the southern Xinjiang region.

Abstract:Objective: This study aimed to explore the influence of different ultramicro grinding intensity on highland barley powder. Methods: Using ultramicro grinding to prepare different granularity of highland barley powder. Exploring the influence of granularity on the apparent characteristics, nutritional quality. Processing characteristics of highland barley powder. Results: The particle size of highland barley powder gradually decreased with the increase of mesh number. The contents of crude fiber, β-glucan, crude fat and ash of highland barley powder decreased with the decrease of particle size. On the other hand, the crude protein and damaged starch increased with the decrease of particle size. 120 mesh highland barley powder had the highest total mineral content (7 476.05 mg/100 g). Among the barley powder, the color of 140 mesh is the brightest, with L^* value of 86.96. The disintegration value (272.00 mPa·s) and recovery value (151.00 mPa·s) of 60-mesh highland barley powder are the lowest. It has a good shear resistance, anti-aging, and anti-rheological. When particle size decreased, the water holding capacity and oil holding capacity of highland barley powder decreased as well. The solubility went lower and the expansion degree went higher. When the particle size of barley powder decreased, the angle of rest, the angle of slip, the density of packing, the density of vibration, the transmittance of barley powder, and the intensity of X-ray diffraction peak increased. Moreover, 140 mesh highland barley powder had the lowest (47.98%) water extraction rate, therefore, it was the most suitable for processing frozen food. Conclusion: The quality characteristics of young barley powder with different grain sizes are different, so appropriate crushing strength should be selected in the production process.

Abstract:Objective: This study aimed to investigate the effects of granularity of paprika on the physical and chemical properties and volatile flavor compounds of chili oil. Methods: Chili oil samples（KLD2-KLD5）were prepared from mechanically crushed paprika with different granularity （35, 30, 26, 20 mesh）, and the content of capsaicinoids, chromatic aberration value, and peroxide value of oil samples were determined by high performance liquid chromatography（HPLC）, colorimeter and other methods. The types and contents of volatile flavor compounds were detected and analyzed by gas chromatography-ion mobility spectrometry （GC-IMS） combined with principal component analysis （PCA）, partial least squares discriminant analysis （PLS-DA）, and heat map cluster analysis. In addition, a comparative analysis was performed with the traditional hand-milled chili oil sample （KLD1）. Results: In the KLD2-KLD5 chili oil samples prepared with mechanically crushed paprika, the concentration of capsaicin, dihydrocapsaicin and capsaicinoids, scoville heat units （SHU） and pungency degree decreased with the increase of the granularity of paprika. The peroxide value increases with the increase of the granularity, and the brightness L^* increased first and then decreased with the decrease of the granularity, and there was a significant difference（P<0.05） had been observed. A total of 58 volatile organic compounds （VOCs） were identified by GC-IMS, mainly including: alcohols, aldehydes, ketones, carboxylic acids, esters, heterocyclics and thioethers, with 10, 18, 12, 4, 7, 5 and 2 types respectively. GC-IMS fingerprints combined with the relative percentage of VOCs showed that the types of VOCs in KLD2-KLD5 samples were the same, but the contents were different. The types and content of VOCs in KLD1 were quite different from those in KLD2-KLD5. Fourteen key differential markers of 5 chili oils were screened by PLS-DA. The results of principal component analysis, nearest neighbor analysis, and heat map clustering analysis of VOCs in five kinds of chili oil samples were consistent with the results of GC-IMS fingerprints. These samples could be accurately distinguished and the flavor of KLD1 was the most unique. Conclusion: The granularity of paprika had a significant impact on the dissolution rate of capsaicin and dihydrocapsaicin in chili oil, peroxide value, and brightness L^* （P<0.05）, but has no effect on the types of volatile flavor compounds in chili oil. However, the content of volatile flavor compounds in each sample had a certain difference.

Abstract:Objective: This study aimed to investigate the effects of drying methods on passion fruit peels. Methods: Passion fruit peels were treated with microwave vacuum freeze-drying, vacuum freeze-drying, heat pump drying, and far-infrared radiation drying. The drying characteristics, rehydration ratio, color difference, dietary fiber, functional properties, microstructure, total phenolic content, total flavonoid content, and antioxidant properties were measured and determined respectively. Results: Heat pump-dried passion fruit peels had poor rehydration ratio and functional properties. Microwave vacuum freeze drying reduced the drying time by 53% when compared tp far-infrared radiation drying, and the microwave vacuum freeze-dried treated passion fruit peels had a higher rehydration ratio (7.45), total phenolic content (13.45 mg GAE/g DW) and antioxidant activity (DPPH was 38.53%, FRAP was 1.14 mmol/L). Additionally, the passion fruit peels were vacuum freeze-dried with treatment to increase their water holding capacity [(21.64±0.21) g/g], oil holding capacity [(6.09±0.71) g/g], swelling [(25.00±1.00) g/g], and total flavonoid content (7.84 mg RT/g DW). Different drying techniques led to higher rehydration ratios, and they also significantly differed (P＜0.05) in terms of dietary fiber, functional properties, total phenolic content, total flavonoid content and antioxidant activity of the peels. Conclusion: The quality of passion fruit peel can be greatly affected by the drying process, and microwave vacuum freeze-drying is the most preferred technique.

Abstract:Objective: To optimize the extraction process of total flavonoids from Aloe vera stir-fry products and investigate its antioxidant activity. Methods: Single factor test and response surface method were used to optimize the extraction process, The content of total flavonoids in Aloe vera raw and fried products from different areas was determined by UV spectrophotometry,The antioxidant activity was studied by DPPH·, ABTS⁺·, ·OH and FRAP methods, the correlation between total flavonoids yield and antioxidant activity was analyzed by Pearson correlation. Results: The optimal extraction conditions were as follows soaking time 3 h, ultrasonic time 15 min, ethanol volume fraction 60% and solid-liquid ratio 1∶10 （g/mL）. The content of total flavonoids in Aloe vera increased. The total flavonoids of Aloe vera raw and fried products from 8 producing areas had certain scavenging effect on four kinds of free radicals, and the concentration was positively correlated with that of Aloe vera, showing good antioxidant activity.Correlation analysis showed that antioxidant capacity was significantly correlated with total flavonoid yield. Conclusion: The optimized extraction process of total flavonoids from Aloe vera stir-fried products is reasonable and feasible, and has strong antioxidant activity.

Abstract:Objective: This study aimed to improve the heat tolerance of Lactobacillus plantarum. Methods: On the basis of the previous research on the microcapsule emulsion, a kind of powder was prepared by spray drying with 2-hydroxypropyl-β-cyclodextrin (2-HP-β-CD). The response surface method is used to optimize different parameters. Its morphology was observed by light microscope and electron microscope, and the particle size was determined by laser particle size analyzer and Zeta potential analyzer; the absorbance change was measured by spectrophotometer, and heat resistance test was carried out by oven heating. Results: With the increase of the ratio of 2-HP-β-CD to emulsion mass, feed rate, inlet air temperature and inlet air rate, and the survival rate first increased and then decreased (P<0.05). By response surface methodology, the optimal parameters of spray drying were obtained as follows: the ratio of 2-HP-β-CD to emulsion mass 3.13, feed rate 288 mL/h, inlet air rate 112 m³/h and the inlet air temperature 118 ℃. Under the control fo these conditions, the survival rate of bacteria was (99.53±0.11)%, and the bacterial load reached 1.64×10⁹ CFU/g. The scanning electron microscopy and microscopy results showed that the microcapsule was a central concave particle, spherically dispersed in water with the bacteria gathered inside. The absorbance value of the water dispersion was not found changing significantly within 1 h (P＞0.05), and the average particle size was 472.7 nm with distribution concentrated and Zeta potential at -40.37 mV. The survival rate of microcapsules was 96.79% when treated at 130 ℃for 60 s, which was significantly different from the survival rate of bacterial sludge (P<0.01). Conclusion: The microcapsule powder has high heat resistance and stable water dispersibility.

Abstract:Objective: This study aimed to reduce the setting time of yogurt, improve the texture of yogurt and evaluate the effect of pea peptides on the quality of coagulated yogurt. Methods: Different amounts（0, 0.50%, 0.75%, 1.00%, 1.25%, 1.50%）of pea peptides were added into milk powder to prepare pea peptide yogurt, and then the setting time, titer acidity, and texture properties of the yogurt were investigated. Results: The results showed that when the amount of pea peptides added was less than or equal to 1.25%, the yogurt setting time could be significantly shortened. When the amount of pea peptide added was 1%, the effect was significant by shortening the coagulation time for 32 min. The addition of pea peptides significantly increased the acidity of yogurt. When the addition amount of pea peptides was less than 1%, the springiness and chewiness of the yogurt were significantly reduced, and the gumminess, cohesiveness, and resilience were significantly increased, which improved the textural properties of the yogurt. Conclusion: The addition of pea peptides to the yogurt fermentation substrate can shorten the fermentation period and enhance the quality of the final product.

Abstract:Objective: This study aimed to provide a new direction for the application of protease restriction modification technique in corn protein. Methods: Corn glutelin was extracted from corn gluten meal. The response surface method was used to optimize the hydrolysis conditions of corn glutelin hydrolyzed by alcalase and protamex. The effects of different hydrolysates on the foam properties of corn glutelin and the additional amount on the quality of chiffon cake were investigated. Results: The optimal hydrolysis conditions for the protease alcalase and protamex on corn gluten were: pH 8, temperature 60 ℃, enzyme dosage 3%, pH 7, temperature 50 ℃, and enzyme dosage 0.81%，respectively. The foaming property and foam stability of hydrolysates were increased. When the amount of alcalase hydrolysate and protamex hydrolysate were 10% and 30%, respectively. The texture characteristics of chiffon cake were the best. At this time, the expansion degree of chiffon cake reached the highest, the hardness and chewability reached the lowest, and the elasticity and recovery reached the maximum. In addition, in this addition amount, its chroma was the closest to that of the 0-addition group. Conclusion: Corn glutelin can be effectively hydrolyzed by alcalase and protamex to obtain glutelin hydrolysates with good foaming properties, which will be beneficial to expand its application in the food industry.

Abstract:Objective: This study aimed to improve the flavor and solubility of extruded corn flour by compounding. Methods: D-optimal mixture design was used to add different proportions of puffed millet flour, fried red rice flour, puffed rice flour, and puffed black rice flour, into puffed corn flour. The composite powder was analyzed and evaluated from the perspectives of caking rate, viscosity, sensory score, and volatile flavor substance changes. The aroma components of different samples were analyzed by gas chromatography-mass spectrometry. Results: The formula of compound powder was as follows: expanded corn flour 50.8%, expanded millet flour 8.8%, fried red rice flour 0.5%, expanded rice flour 19.9%, and expanded black rice flour 20.0%. Compared with the single extruded corn flour, the caking rate of the composite powder was reduced to 0.52%, the viscosity was increased to 2 880 mPa·s, the sensory score was 87.84 points, and the blending performance was also significantly improved. The flavor substances in the compounded extruded corn flour, such as a green aroma and a nut aroma was increased. To be noticed, the increasing of aldehydes is the most obvious. Conclusion: The quality of the compounded extruded corn flour was improved, and the volatile flavor substances were increased.

Abstract:Objective: This study aimed to explore a kind of food with low glycemic index (GI) and SDS serial products. Methods: Using highland barley powder as raw material. The optimal enzymolysis conditions were determined by single factor test and response surface test. The hypoglycemic activity of α-glucosidase and α-amylase in vitro was evaluated. Results: The content of slow digestion starch in the enzymolysis highland barley powder reached the highest of 16.55%, under the control of the conditions of 60 U/g β-amylase, 3.5 h enzymolysis time, 51 ℃ enzymolysis temperature, and 1∶12 (g/mL) solid to liquid ratio. Meanwhile, the modified highland barley powder had a certain inhibitory effect on α-glucosidase and α-amylase. The highest inhibitory rates of the modified highland barley powder on α-glucosidase and α-amylase were 71.39% and 48.32%, respectively. Conclusion: Under the control of the optimal enzymatic hydrolysis conditions, the content of slow digestible starch in the enzymatic modified highland barley powder was significantly increased.

Abstract:Objective: This stydy aimed to develop a new type of fried potato ball and evaluate its quality. Methods: In this study, potatoes were used as the main raw materials to make mashed potatoes after cooking and then fried into potato balls. The effects of whey protein addition on color difference, texture properties, rheological properties, sensory quality and starch digestibility of fried potato balls were explored. Results: Compared with non-whey protein addition, the supplementation of whey protein could significantly improve the L^* （brightness value）, a^* （redness value）, and the cohesion, adhesion, and elasticity of potato balls （P＜0.05）. The higher the amount of whey protein powder （0 ~ 2.5 g/100 g）, the lower the hardness and the higher the elasticity of potato balls. The addition of whey protein can promote the starch digestibility of fried potato balls. Conclusion: The color, taste, hardness, elasticity and other comprehensive qualities of fried potato balls were the best when the whey protein supplemental level was 2 g/100 g.

Abstract:Egg white protein is a high-quality protein with high nutritional value and a variety of functional properties. The oligosaccharides can be covalently bound to the egg white protein through the glycosylation reaction, and the functional properties of the conjugates were improved compared with the natural egg white protein. In this review, the gel mechanism of oligosaccharide-egg white protein conjugates was reviewed, and the influencing factors of oligosaccharide-modified egg albumin gels were discussed. Moreover, effects of oligosaccharides on the functional properties of egg albumins were summarized, and the processing and application of oligosaccharide-modified egg albumin were prospected.

Abstract:The review summarized the latest domestical and international research progress in the biosynthesis pathway, safety, extraction process, and biological activity of oleuropein in recent years. The problems in the olive industry was analyzed and its future development direction was prospected.