Abstract:Objective To improve the activity of D-lyxose isomerase under acidic conditions.Methods Solvent-accessible surface bioinformatics analysis was performed on surface residues of D-lyxose isomerase derived from Caldanaerobius polysaccharolyticus, and six mutation sites, i.e., K2D, K2E, K8D, K8E, K18D, and K18E, were designed. Mutants were constructed and subjected to recombinant inducible heterologous expression in Escherichia coli. The recombinant mutant enzymes were isolated and purified using a nickel affinity chromatography column. In vitro comparative experiments were conducted to evaluate the catalytic conversion of D-fructose to D-mannose by the recombinant mutant enzymes at acidic pH 5.5 and near-neutral pH 6.5.Results The recombinant mutant enzymes K8D and K8E showed significantly improved catalytic conversion rates of D-fructose, with the conversion rate reaching 140% under optimal conditions (pH 6.5). At pH 5.5, the conversion rate was 1.26 times higher than that of the wild-type enzyme.Conclusion Molecular modification successfully enhanced the catalytic activity of D-lyxose isomerase mutants under acidic conditions.

Abstract:Objective To explore the activation effect of casein (CN) on neutrophils and its interaction with TLR4 receptors on the neutrophil surface.Methods The zebrafish model is adopted to study the activation effect of CN on neutrophil migration, with such methods as 3D model construction, molecular docking, and molecular dynamics simulations employed to study the interaction between TLR4 receptors and CN subtypes.Results Treatment of 3 dpf zebrafish with 1 mg/mL of CN solution for 2 h can induce neutrophil migration and accumulation inside the body of the zebrafish. All subtypes of CN can form stable complexes with TLR4. It is speculated that the key amino acids that maintain the stability of the complexes between α_S1-CN/α_S2-CN and TLR4 mainly bind via hydrogen bonds and hydrophobic interactions, while the key amino acids that maintain the stability of the complexes between β-CN/κ-CN and TLR4 mainly bind by hydrogen bonds.Conclusion CN can bind to TLR4 via hydrogen bonds and hydrophobic interactions, and mediate the activation of neutrophils, thus exerting its immunomodulatory effects.

Abstract:Objective To isolate and identify highly effective strains capable of removing chemical oxygen demand (COD) and ammonia nitrogen from antibacterial wastewater.Methods Metagenomic sequencing technology is employed to deeply explore the microbial resources in wastewater isolated by freshly-extracted Zanthoxylum oil. The strains with the ability to efficiently remove COD and ammonia nitrogen are accurately analyzed. The strains with pollution-reducing potential are screened from wastewater enriched through natural outdoor cultivation for one month.Results Proteobacteria and Firmicutes are the predominant phyla in the wastewater isolated by freshly-extracted Zanthoxylum oil, while Enterobacter and Acetobacter are the dominant genera. Three strains with significant COD and ammonia nitrogen removal capabilities are selected and identified as Bacillus stercoris strain X4, Pseudomonas putida X21, and Pseudomonas taiwanensis X22. In actual wastewater treatment, the COD removal rate of these three strains after 8 days is 55.47%, 50.76%, and 52.32%, respectively, while the ammonia nitrogen removal rate after 36 hours is 55.93%, 54.19%, and 40.79%, respectively.Conclusion The strains identified through indigenous enrichment in Zanthoxylum oil wastewater are more effective in reducing pollution than those from other sources.

Abstract:Objective To compare the effects of roasting and microwave conditions on odor compounds in walnut oil.Methods Identification of odor compounds in roasted walnut oil (140 ℃ roasting for 15 and 30 min; 160 ℃ roasting for 15 and 30 min) and microwaved walnut oil (700 W for 1, 3, 5, and 7 min) is performed by gas chromatography-mass spectrometry (GC-MS).Results A total of 74 odor compounds are identified, and the mass fraction of odor compounds gradually rises with increasing roasting temperature and microwave time. Aldehydes and heterocycles are the most dominant odor compounds in walnut oil. The 3-methyl butanal, pentanal, phenylacetaldehyde, 2,3-butanedione, 2,3-pentanedione, 2-pentylfuran, and 2-ethyl-6-methylpyrazine are determined to be the key odor compounds in roasted walnut oil (160 ℃ roasting for 30 min) and microwaveable walnut oil (700 W for 7 min). The roasted walnut oil (160 ℃ roasting for 15~30 min) and microwave walnut oil (720 W for 7 min) have the strongest odor, followed by roasted walnut oil (140 ℃ roasting for 30 min) and microwave walnut oil (720 W for 3~5 min); While roasted walnut oil (140 ℃ roasting for 15 min) and microwave walnut oil (720 W for 1 min) have the weakest odor.Conclusion Roasting at high temperature for a long time (160 ℃ roasting for 30 min) promotes the formation of heterocyclic compounds more effectively, while microwave treatment can achieve a comparable flavor intensity in a shorter time (7 min). Both methods are effective in enhancing the odor intensity of walnut oil.

Abstract:Objective To solve the problem that pumpkin seed oil (PSO) prepared by critical fluid extraction contains more impurities, this paper employs two types of SiO₂ to refine the PSO at low temperature and study the influence of them on the quality characteristics of the oil.Methods Gas chromatography, high performance liquid chromatography, and ultraviolet spectroscopy are adopted to analyze and compare the quality difference of PSO prepared from two critical fluids and the influence of low-temperature refining treatment of SiO₂ on PSO quality characteristics.Results The results show that the fatty acid content and composition of PSO extracted by two critical fluids are similar, and PSO prepared by the subcritical extraction contains more α-tocopherol, γ-tocopherol, total phenols, β-carotene, and higher antioxidant activity. Meanwhile, PSO prepared by the supercritical extraction includes higher squalene and sterol content. After two types of SiO₂ refining treatment, the most fatty acid content in PSO remains basically unchanged (P>0.05), but the acid value, peroxide value, and color decrease. Additionally, both trace active ingredients and antioxidant activity in PSO are significantly reduced (P<0.05). Among them, the loss of trace active ingredients in PSO ranges from 8.9% to 24.6%, while the loss rates of OSI, DPPH, and FRAP are between 3.2% and 7.4%, 13.2% and 26.5%, and 15.3% and 26.4% respectively. In addition, after PSO is refined with two types of SiO₂, the total amount of phospholipids is reduced by more than 85%. The results of principal component analysis and clustering analysis show that the preparation process and low-temperature refining treatment of SiO₂ have significant effects on the quality characteristics of PSO.Conclusion SiO₂ refining treatment can significantly improve the quality characteristics of PSO prepared by critical fluid extraction.

Abstract:Objective To explore the differences in volatile flavor profiles and discriminate odor characteristics among four kinds of commercially available fermented soybean paste.Methods A comprehensive analysis of the differences in volatile flavor profiles and odor characteristics of four types of fermented soybean paste is conducted by sensory profile, electronic nose, and gas chromatography-ion mobility spectrometry (GC-IMS).Results The main volatile organic compounds (VOCs) in the four types of Northeast Chinese fermented soybean paste are esters, acids, aldehydes, ketones, and heterocyclic volatiles such as pyrazines, furans, and pyrroles. Sour and putrid aromas are the core odors contributing to the "pungent odor" of fermented soybean paste. CJ1 exhibits a more intense and irritating "stinky" odor, CJ2 demonstrates a more layered aroma profile, CJ3 shows a more harmonious aroma, and CJ4 has a milder pungent odor with more pronounced, softer, fresh, and floral aromas. Significant differences in odor characteristics are observed among different fermented soybean paste types.Conclusion The combination of sensory profile, electronic nose, and GC-IMS can effectively distinguish and discriminate the volatile flavor characteristics of the four commercially available fermented soybean paste types.

Abstract:Objective To investigate the preparation of potato protein fiber (PPF) based on enzymatic method, and further analyze their structural and functional properties.Methods PPF is prepared from potato protein isolate (PPI) through enzymatic hydrolysis with trypsin (Tyr) and acid-heat treatment. The effects of protein mass concentration, heating time, Tyr activity, and heating temperature on the fluorescence intensity of PPF are studied. Structural properties of PPF are characterized by infrared spectroscopy, fluorescence spectroscopy, etc. With curcumin (Cur) as an encapsulated object, the encapsulation efficiency, loading capacity, thermal stability, and antioxidant activity of PPF-Cur complexes are investigated.Results During the fibrosis process of PPF, the β-sheet content increases from 28.12% to 32.29%, and the α-helix content increases from 22.53% to 25.87%. When the protein mass concentration ranges from 0.2 to 0.8 mg/mL, the Trp fluorescence peak of PPF exhibits a redshift, and its fluorescence intensity is higher than that of PPI. When the Cur concentration increases from 20 to 100 μg/mL, the encapsulation efficiency of PPF-Cur increases from (64.66±0.25)% to (96.16±0.20)%, representing a 48.72% increase, while the loading capacity increases from (3.25±0.01) to (19.62±0.02) μg/mg, a 5.04-fold increase. After heating for 120 min, the retention rates of free Cur and PPF-Cur are (74.40±0.32)% and (87.83±0.61)%, respectively. At Cur concentrations of 20~40 μg/mL, the scavenging rates of PPF-Cur against DPPH free radicals and ABTS? free radicals reach 66.46% and 47.87%, respectively.Conclusion Food protein fibers prepared by enzymatic method combined with acid heat treatment can improve the structural and functional properties of proteins.

Abstract:Objective To study the composition and structural characteristics of polysaccharides from roasted beans of Coffea arabica.Methods Roasted beans of C. arabica were used as raw materials. The hot water extraction combined with alcohol precipitation method was optimized using the response surface methodology to extract polysaccharides. The crude polysaccharide was purified using the Sevag method, macroporous resin, cellulose column, and gel separation technology. Total sugar, total phenol, total flavonoid, and monosaccharide compositions were analyzed using the phenol-sulfuric acid method, Folin-Ciocalteu assay, NaNO₂-AlCl₃-NaOH method, and ion chromatography, respectively. The structural characteristics of the polysaccharides were characterized by infrared spectroscopy (IR) and scanning electron microscopy (SEM). Additionally, the in vitro antioxidant activity of the polysaccharides was evaluated.Results The optimal extraction conditions for polysaccharides from roasted coffee beans were as follows: extraction temperature of 80.4 ℃, extraction time of 48 min, liquid-to-solid ratio of 15.3∶1 (mL/g), and ethanol volume fraction of 75%. Under these conditions, the polysaccharide yield was (7.56±0.26)%. After purification, five polysaccharides (RBP1, RBP2, RBP3, RBP4, and RBP5) were obtained, which were primarily composed of galactose (Gal), rhamnose (Rha), glucose (Glc), arabinose (Ara), and mannose (Man). The infrared spectra of the polysaccharides showed characteristic absorption peaks near 3 300~3 500 cm^-1, 2 900~3 000 cm^-1, 1 600 cm^-1, 1 400~1 300 cm^-1, and 1 000 cm^-1. SEM images showed that the polysaccharides exhibited a series of compact, porous structures, with RBP4 displaying a dense and regular pore structure. The antioxidant activity results showed that RBP0 had the strongest antioxidant capacity, which increased with concentration in the range of 0.1~0.5 mg/mL. The DPPH radical scavenging ability increased from (1.53±0.32)% to (82.85±0.61)%, and the iron reduction ability (FRAP method) increased from (0.39±0.000 48) mmol/g Fe²⁺ to (3.03±0.001 9) mmol/g Fe²⁺.Conclusion The polysaccharides from roasted beans of C. arabica are vesicular polysaccharides primarily composed of galactose, rhamnose, glucose, arabinose, and mannose.

Abstract:Objective To rapidly quantify four major organic acids in 47 base wines of Fuyuxiangxing crude Baijiu using near-infrared spectroscopy (NIR) and chemometrics.Methods The study used the Kennard-Stone (K-S) algorithm to divide the samples, combined with preprocessing strategies such as normalization, standard normal variate transformation (SNV), and Savitzky-Golay smoothing. Model parameters were optimized through cross-validation, and the effects of the number of principal components and band selection on the performance of the principal component regression (PCR) and partial least squares regression (PLSR) models were evaluated.Results The validation results showed that the prediction correlation coefficients (Rc2) of the PCR models for the four major organic acids (acetic acid, n-butyric acid, n-pentanoic acid, and n-hexanoic acid) were all higher than 0.9, and the root mean square errors of prediction (RMSEPs) were all lower than 7. The Rc2 values of the PLSR models were all higher than 0.8, and the RMSEPs were all lower than 8, indicating that the models had good generalization ability and prediction accuracy.Conclusion NIR combined with PCR and PLSR modeling methods can effectively achieve the rapid quantitative analysis of the four organic acids in Fuyuxiangxing crude Baijiu base wine.

Abstract:Objective To develop a rapid and accurate method for the determination of carbendazim residues in vegetable oils.Methods Three-dimensional fluorescence spectroscopy combined with chemometrics was used for the quantitative analysis of carbendazim residues in vegetable oils. Three different vegetable oil extracts were added to carbendazim to prepare samples, and their three-dimensional fluorescence spectra were measured. Parallel factor (PARAFAC), full-rank parallel factor (FPA-PARAFAC), and alternating trilinear decomposition (ATLD) were used to analyze carbendazim in the samples. The figures of merit (FOM), such as selectivity, sensitivity, detection limit, and quantification limit, were calculated for the three algorithms, and tested using the elliptical joint confidence region (EJCR).Results The recovery rates of carbendazim for PARAFAC, FPA-PARAFAC, and ATLD were 96.98%~112.64%, 97.05%~112.36%, and 93.07%~104.47%, respectively, with the average recovery rate for ATLD being closer to 100%. In FOM and EJCR analysis, ATLD outperformed the other two algorithms.Conclusion The use of three-dimensional fluorescence spectroscopy combined with chemometrics for the determination of carbendazim residues in vegetable oils provides excellent quantitative results.

Abstract:The health hazards of high sugar and high salt foods have led to an increasing chronic disease burden globally, which has become a major challenge in public health. By analyzing the legislative practices of health taxes in countries including Mexico, Chile, and the United Kingdom, it is identified that foreign health taxes have the advantages and disadvantages of a single, comprehensive, and tiered tax rate model. The public consumption behavior changes, health benefits, and negative issues are also evaluated. Given this, the necessity and feasibility of health tax legislation for high sugar and high salt foods in China are further explored. A health tax legislative framework is proposed, involving tax system elements, procedural rules, and supporting policies. Besides, it is suggested to adopt a three-stage implementation path of "top level design-pilot exploration-comprehensive promotion" on this basis to realize the health tax system and promote the Healthy China strategy implementation.

Abstract:Objective To address the limitations of traditional single-point moisture measurement in complex drying environments, a multi-conductor array capacitor device was designed for moisture content measurement inside a grain dryer.Methods An array of 8 conductor rods was arranged to measure the capacitance between each pair of adjacent rods, from which the average dielectric constant in the inter-rod regions was calculated to enable real-time moisture monitoring during the grain drying process.Results High-precision capacitance measurements were achieved using an FDC2214 capacitive sensor controlled by a Raspberry Pi Pico W. The relationship between the dielectric constant in regions with varying moisture content and the corresponding water weight was validated, generating a two-dimensional dielectric constant distribution map. In environments with uneven humidity distribution, the device rapidly and stably detected moisture diffusion and accurately fitted the improved Dobson model. During the fitting process, the maximum standard deviation of the dielectric constant was 3.98, with an average value of 1.27.Conclusion By adjusting the physical structure of the test setup, the device can measure the average moisture distribution in any spatial unit of grain.

Abstract:Objective To investigate the production procedures for moderately processed wheat flour, with the aim of improving milling efficiency, reducing raw material loss, and enhancing flour quality.Methods The milling process was conducted by regulating key steps (wheat conditioning, sifting, bran milling, and roll spacing adjustment). Flour quality was comprehensively evaluated based on flour yield and flour characteristics to determine the optimal moderate processing procedure.Results The roll spacing adjustment-non-conditioning process yielded the highest flour output (72.05 g/100 g), representing an increase of 8.96% compared to the control group and 14.24% compared to the non-conditioning process. Moreover, the protein content of flour obtained through the roll spacing adjustment-non-conditioning method increased by 7.97% compared to the non-conditioning method. Milling processes involving increased roll spacing, such as roll spacing adjustment-non-conditioning, roll spacing adjustment-second sifting, and roll spacing adjustment-second bran milling, resulted in increases in total phenolic content by 56.85%, 53.76%, and 40.38%, respectively, compared with the same processes using smaller roll spacing. The highest short-range ordered structure of wheat starch was observed under the roll spacing-adjusted bran milling process.Conclusion The roll spacing adjustment-non-conditioning process is the optimal moderate processing method for achieving overall superior flour quality. Appropriately increasing roll spacing during milling is a feasible strategy for moderate wheat processing, which can enhance the total phenolic and ash content of flour while reducing its whiteness.

Abstract:Objective To investigate the effect of a low-voltage electrostatic field (LVEF) on the quality of frozen sheep liver.Methods Fresh sheep liver was used as raw material, cooked, and then frozen under different temperatures (-20, -40 ℃) with LVEF assistance. Periodic sampling was conducted to analyze changes in color, thawing loss rate, pH value, hardness, chewiness, total viable count (TVC), total volatile basic nitrogen (TVB-N), vitamin A content, microstructure, and moisture distribution during storage.Results After 30 days of storage, the TVC, TVB-N content, pH value, and vitamin A content in the LVEF-assisted -40 ℃ group were 3.38 lg(CFU/g), 13.37 mg/100 g, 6.06, and 8 016 μg/100 g, respectively. The thawing loss rate, color, hardness, and chewiness in this group were higher than those in the control group, indicating significantly better storage quality (P<0.05). Scanning electron microscopy images showed that the LVEF-treated samples exhibited a neatly and tightly arranged structure with minimal damage. T₂ relaxation time analysis demonstrated that LVEF effectively prevented the transition of immobilized water into free water, thereby improving the water retention capacity of sheep liver.Conclusion LVEF can mitigate changes in the storage quality of sheep liver and reduce ice crystal damage to its internal structure after freezing.

Abstract:Objective To explore the effect of polysaccharide water-retaining agents, such as carrageenan and modified starch, combined with mild cooking on the eating quality of sterilized braised chicken, and to improve the edible quality of pre-cooked braised chicken suitable for room-temperature storage.Methods Under mild cooking conditions, the tenderness retention effects of carrageenan and modified starch, used individually and in combination, were first compared. A single-factor test was then conducted on the better-performing treatment group. Based on the results of the single-factor test, a comprehensive experiment was carried out, and the optimal ratio of polysaccharide water-retaining agents obtained from the comprehensive test was further verified. The quality of braised chicken was evaluated by measuring shear force, texture profile analysis, cooking loss rate, color, and sensory attributes.Results The combined use of carrageenan and modified starch resulted in better tenderness of the chicken, with the optimal combination being 0.2% carrageenan and 0.5% modified starch. Braised chicken treated with this combination of polysaccharide water-retaining agents and mild cooking showed better retention of eating quality after sterilization, including improved tenderness, reduced hardness, lower cooking loss, enhanced meat glossiness, better mouthfeel, and favorable taste.Conclusion The combination of carrageenan and modified starch with mild cooking can, to a certain extent, alleviate the quality deterioration of braised chicken caused by sterilization..

Abstract:Objective To explore the differences in cytotoxicity, antioxidant, and hypoglycemic activities of resveratrol, oxy-resveratrol, and piceatannol, three stilbene compounds with similar structures.Methods The cytotoxicity, extracellular/intracellular antioxidant activity, and hypoglycemic activity of the three compounds are analyzed by Cell Counting Kit-8 (CCK-8), total antioxidant activity, cellular antioxidant stress ability, intracellular reactive oxygen species (ROS) content, cellular antioxidant activity (CAA) assay, and α-glucosidase inhibitory activity.Results Compared with oxy-resveratrol and resveratrol, piceatannol shows lower cytotoxicity, better extracellular antioxidant activity, and α-glucosidase inhibitory activity. All three stilbenes effectively mitigate the oxidative stress damage of HepG2 cells induced by H₂O₂ solution and reduce the ROS content in HepG2 cells in a dose-dependent manner. Oxy-resveratrol demonstrates a stronger capacity to inhibit the generation of oxygen free radicals induced by ABAP in HepG2 cells.Conclusion The three stilbene compounds all have high antioxidant activity and hypoglycemic activity.

Abstract:Objective To investigate the nutritional quality and flavor characteristics of the unique lotus sprout in Caidian.Methods A texture analyzer, electronic nose, solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS), and gas chromatography-ion mobility spectroscopy (GC-IMS) were used to analyze the textural properties and volatile organic compounds (VOCs) of three primary lotus sprout varieties, i.e., "Maosanjie", "Baiyuzan 2", and "Elian 5" in Caidian. The nutritional quality of these three lotus sprouts was comprehensively evaluated through principal component analysis.Results Significant differences were found in the nutritional quality of the three lotus sprout varieties, except for starch content. The cumulative contribution rate of the two principal components was 92.612%, effectively reflecting the comprehensive nutritional quality of the lotus sprouts. Baiyuzan 2 ranked first in terms of overall score. Maosanjie exhibited superior textural characteristics compared to the other two varieties. The overall flavor components of the three lotus sprouts were similar, with a higher content of small molecular volatile organic compounds. The flavor substance content in Maosanjie and Elian 5 was higher than that in Baiyuzan 2. Three common characteristic flavor compounds, 2-pentyl furan, phenylacetaldehyde, and nonanal, were detected in all three lotus sprout varieties using SPME-GC-MS and GC-IMS. The relative content of aldehydes, esters, and ketones in the volatile components of the three lotus sprouts ranged from 22.10% to 30.06%, 19.76% to 20.42%, and 18.67% to 24.47%, respectively, making significant contributions to the formation of the lotus sprout flavor. Aldehydes were the most prominent volatile compounds and played a key role in shaping the characteristic aroma of the lotus sprouts. Through orthogonal partial least squares discriminant analysis (OPLS-DA), 17 volatile compounds with significant contributions were selected. Furthermore, a correlation between the quality and flavor of the lotus sprouts was found.Conclusion Caidian lotus sprout is rich in nutrition, has a unique aroma, and shows broad market prospects.