The production of 1,6-hexanediamine as the synthetic monomer of nylon 66 is mainly monopolized by foreign countries, and the traditional chemical synthesis of hexanediamine contains highly toxic cyanide, high technical barriers, long production process, how to use the biological method to make innovative breakthroughs in the context of carbon neutrality has become a challenge.However, up to now, no natural hexanediamine synthesis pathway has been reported.In this study, 6-aminohexanoic acid, a widely available substrate, was used to construct a synthetic pathway for hexanediamine through component-adapted assembly, and fermentation enhancement was combined to increase the yield of hexanediamine in engineered strains.Finally, excellent carboxylic acid reductase MAB CAR L342E, single transaminase HATA, and double transaminase combination PatA/VFTA were obtained through screening, and the initial hexanediamine yields of the engineered strains after combination could reach 3.01 mg/L (DAH4) and 8.50 mg/L (DAH37), respectively.On this basis, the fermentation conditions were optimized, and the yields of 1,6-hexanediamine reached 64.33 mg/L and 153.93 mg/L, which were 20.37 times and 17.11 times higher than those before optimization, respectively.This study has successfully constructed a pathway for the synthesis of hexanediamine by biological method, which provides technical support for the breakthrough of domestic chemical products.

1,6-Hexanediol is widely used in the fields of polyester polyols and UV-curable materials, etc.However, the traditional chemical synthesis is mainly monopolised by foreign countries with high technological barriers, and the preparation of biobased hexanediols in the context of carbon neutrality has received wide attention.The aim of this study was to construct an efficient hexanediol synthesis pathway in Escherichia coli by component-adapted assembly using biobased adipic acid as the raw material, with fermentation enhancement to increase the yield of biobased 1,6-hexanediol and its conversion rate.The optimal fermentation strain was constructed by mining the aldo-keto reductase isozyme and assembled with the carboxylic acid reductase from Mycolicibacterium smegmatis MC2 155, and the yield of 1,6-hexanediol was increased by 6.4-fold compared with that of the original strain to reach the titer 61.8 mg/L.On the basis of the fermentation enhancement study, the optimal conditions were determined to be the TB medium and the concentration of the substrate 10 g/L, induction time of 2.5 h, and initial sugar concentration of 8 g/L, at which the yield of 1,6-hexanediol reached 818.16 mg/L, which was 84.7-fold higher than that of the initial strain, and the conversion rate reached 85%.This study provides a new idea for the biosynthesis of 1,6-hexanediol.

Putrescine is mainly used in the preparation of high-temperature-resistant nylon PA46.Currently, it is mainly monopolized due to the high technical barriers derived from using highly toxic hydrocyanic acid and acrylonitrile as raw materials.To address the low yield and productivity in the biological synthesis of putrescine, this research improved the substance transfer efficiency via permeabilization of cells based on a biocatalytic route from arginine to putrescine, and the synthesis ability was enhanced through engineering strain cultivation and catalytic process enhancement.The results showed that the ethanol permeabilization treatment could significantly enhance the mass transfer limitation, and the putrescine yield was enhanced by more than 50% compared with the control, reaching 14.92 g/L.Meanwhile, the optimal cultivation conditions and the catalytic process were determined, and the putrescine yield reached the highest reported level of 88.67 g/L,with a molar conversion rate 0.81 mol/mol and a production efficiency of 2.46 g/(L·h), laying the foundation for the subsequent development of biobased putrescine.

As a rose-scented aromatic alcohol, 2-phenylethanol has been widely used in the fields of food, daily chemicals, and medicine.In this study, a wild-type aroma-producing yeast (Saccharomyces bayanus) selected from fermented sauce mash was utilized to explore its ability to produce 2-phenylethanol through biotransformation methods.A biotransformation method suitable for producing 2-phenylethanol by S.bayanus was established by optimizing the ingredients of glucose, substrate L-phenylalanine, yeast nitrogen base, and other inorganic salts in the reaction system.It was shown that the highest titer of 2-phenylethanol was obtained after 48 h of transformation.On this basis, by further optimizing the concentrations of carbon source, amino acceptor of α-ketoglutaric acid as well as the mixed ionic nutrient solution, the titer of 2-phenylethanol was reached to 4.83 g/L, an increase of 67.13% compared to that of the initial conversion conditions. Finally, by optimizing the pH, temperature, and dissolved oxygen of the conversion system, the concentration of 2-phenylethanol reached 6.05 g/L, an increase of 109.34% compared to that of the initial conversion conditions.The 2-phenylethanol obtained by this method not only has good properties and the safety of natural products, but also has a high yield and conversion rate.In addition, the process also has the characteristics of short cycle and low cost.Therefore, this biological transformation method has good application prospects.

Rebaudioside A (RA) is a low-calorie sweetener extracted from stevia and is considered an ideal substitute for sucrose.However, its potential applications in the food industry are limited due to the unpleasant aftertaste.Moderate enzymatic glycosylation of RA has been identified as an efficient approach to mitigate its aftertaste.Cyclodextrin glucosyltransferase (CGTase) is currently the predominant enzyme utilized for catalyzing RA glycosylation.Nevertheless, a major drawback of CGTase lies in the complexity and diversity of its reaction products, particularly with regard to the high proportion of long-chain glycosylated products, which severely impact the taste and quality of the resulting products.In this study, various CGTases from different sources were explored for RA glycosylation reaction.Ultimately, α-CGTase from Paenibacillus macerans was selected due to its exceptional conversion and significant specificity for short-chain products.After extensive investigation of enzymatic properties and optimization of reaction conditions, this study successfully determined the optimal reaction condition, which was employing a phosphate buffer (pH 6.0), using soluble starch as the glycosyl donor, and maintaining a substrate mass ratio of RA∶soluble starch=1∶1.With an enzyme concentration of 25 μg/mL and a reaction time of 12 h at 40 ℃, the maximum conversion of RA was achieved at 74.8%.The proportion of short-chain products (RA-nG, n≤2) in the total products increased to 86.5%, representing a 10% enhancement compared to the pre-optimized conditions.Therefore, this study effectively improves the specificity of short-chain glycosylated RA, thereby demonstrating its significant potential for industrial applications of steviol glycosides.

Endo-polygalacturonase is one of the most widely studied enzymes in pectinases, which specifically hydrolyzes the α-1,4-glycosidic bonds of polygalacturonic acid chains, generating oligogalacturonic acids of different polymerization degrees.This enzyme holds significant importance in enhancing the added value of pectin.Currently, research on this enzyme remains limited, and its poor catalytic activity and thermal stability are major factors limiting its industrial application.In previous work, a novel endo-polygalacturonase gene from Penicillium arizonense (pePGB) was obtained and heterologously expressed in Komagataella phaffii.However, its catalytic activity was only at a moderate level compared to similar enzymes.Therefore, this study focused on enhancing its catalytic activity.Initially, alanine scanning of amino acids in the substrate binding pocket subsites was conducted.Based on the scanning results and sequence alignment, specific mutation hotspots were chosen for rational design.Three mutants with increased enzymatic activity, V248L, V248R, and G111R, were screened.The beneficial mutations were combined to obtain an optimal mutant, G111R/V248R, which showed 1.84-fold and 2.06-fold improvements in specific activity and catalytic efficiency (k_cat/K_m), respectively.Homology modelling and molecular docking analysis revealed that the mutation of valine to arginine at position 248 formed two hydrogen bonds with the substrate, enhancing the enzyme-substrate interaction.While the mutation at position 111 did not directly affect the enzyme-substrate interaction.It likely synergized with the arginine at position 248 and collectively increased the positive charge of the substrate pocket, resulting in an increased binding affinity with negatively charged substrates, consequently enhancing the catalytic activity.This study lays an important foundation for the application of this enzyme in industries such as juice processing and provides valuable insights for rational design aimed at enhancing enzyme catalytic activity.

In order to explore the key structural characteristics of gum ghatti (GG) for emulsification, five GG components with different structures were obtained by partial acid hydrolysis, and their structures were characterized by ion chromatography, Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry.The conjugate was formed with soy protein isolate (SPI) by Maillard reaction, and the oil-in-water emulsion was prepared.The physicochemical properties and emulsifying properties of the conjugates were investigated by infrared, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, particle size analysis and zeta potential.The results showed that with the progress of acid hydrolysis, the uronic acid and protein content of GG gradually increased, the molecular weight gradually decreased, and the degree of branching gradually decreased.The GG after acid hydrolysis could form a stable conjugate with SPI.The solubility of SPI could be significantly improved by covalently combining GG with lower branching degree with SPI (36.60%>22.31%), and the absolute potential value of GGA5-SPI conjugate with the lowest branching degree was significantly higher than that of GG-SPI (53.63 mV>46.99 mV), and the emulsion system was more stable.In summary, Maillard reaction could significantly improve the functional properties and emulsifying properties of GG-SPI conjugates, and the lower the branching degree of GG, the better the emulsifying ability and the higher the stability of the conjugates.The results are expected to provide a theoretical basis for the development and application of sugar-protein emulsifiers.

Inhibiting the activity of acetylcholinesterase (AChE) is beneficial to the elevation of acetylcholine levels thereby alleviating cognitive impairment and memory decline in the elderly.In this study, the active ingredients in soymilk and fermented soymilk were extracted by ethanol solvent, and the AChE inhibitory activity of the two extracts was measured.Then, ultra-performance liquid chromatography quadrupole time of flight mass spectrometry was used to identify the extracts in the chemical components.The differential components with significant content changes before and after fermentation were screened by SIMCA software.After that, molecular docking technology was used to screen the active ingredients among the differential components, and their binding ability and interaction forces with AChE were explored.Results showed that lactic acid bacteria fermentation can significantly (P<0.05) improve the AChE inhibitory activity of soymilk, and its IC₅₀ value decreased from 3.24 mg/mL to 2.55 mg/mL.A total of 84 components were identified from soymilk and fermented soymilk extracts, of which 19 components had significant content changes before and after fermentation.The molecular docking results showed that 13 components were able to tightly bind with AChE.These active ingredients mainly interact with amino acid residues in AChE active sites through hydrogen bonding and hydrophobic interactions, thereby inhibiting AChE activity.

Transglutaminase (TGase) can promote intramolecular or intermolecular cross-linking of proteins, and is widely used in food, pharmaceutical, textile, and other industries.In order to efficiently produce TGase with excellent properties, two TGases from Streptomyces mobaraensis were investigated in this study.The properties of two TGases from different strains were investigated, and the TGase gene tg_LD with excellent properties was heterologously expressed in Escherichia coli using six different plasmids, respectively.Mature TGase was successfully expressed in the recombinant E.coli BL21(DE3) (pET32a-tg_LD).The activity of recombinant TG_LD reached 0.45 U/mL after 8 h induction using 0.2 mmol/L IPTG at 25 ℃.In order to further improve the expression level of TG_LD, two recombinant strains were constructed to specifically activate pro-TGase, respectively.The activity of TG_LD in recombinant E.coli BL21(DE3) (pCOLDII-pro-EK-tg_LD) after activation in vitro reached 25.23 U/mL after 24 h induction using 0.2 mmol/L IPTG at 15 ℃.Activated TG_LDwith excellent properties were efficiently expressed in E.coli in this study.

Aldehydes and phenols in the undetoxified hydrolysate inhibited growth and fermentation of the strain.Candida glycerinogenes have multiple resistance properties, and recombinant strains were constructed by overexpressing relevant resistance genes and screened.Compared with the control strain, the recombinant strain overexpressing CgGCN4 increased the biomass of C.glycerinogenes by 25.2%, 14.6%, and 5.2%, and the glucose consumption rate by 9.9%, 5.5%, and 13.1%, respectively, in a high-glucose medium containing 3.0 g/L furfural, 2.0 g/L vanillin and 3.5 g/L acetic acid, and increased glycerol production by 23.4% under the stress of 3.0 g/L furfural.Under the stress of furfural, vanillin or acetic acid, the increase of intracellular reactive oxygen species level of the recombinant strains was reduced by 35.2%, 28.0%, and 15.3%, respectively, and the binding level of propidium iodide was reduced to different degrees, suggesting that the recombinant strains could maintain the excellent growth and fermentation performance of the strains by reducing the accumulation of intracellular reactive oxygen species and maintaining the integrity of the cell membrane.Application of the resistant recombinant strain to open fermentation of undetoxified bagasse hydrolysate for glycerol production resulted in a 20.0% increase in sugar consumption rate, a 12.3% increase in biomass and a 21.7% increase in glycerol yield.This study provides new ideas and genetic resources for the application of undetoxified cellulose hydrolysate.

Based on the surface display system of Saccharomyces cerevisiae spores, the immobilization of polyethylene terephthalate (PET) hydrolase FAST-PETase was achieved.By using the integrated plasmid pRS306-TEF1pr-ss-FAST-PETase, the gene encoding FAST-PETase was inserted into the genome of the dit1Δ defective strain of S.cerevisiae to enable more stable protein expression.Using bis(2-hydroxyethyl) terephthalate (BHET) as the substrate, the optimal reaction conditions, thermal stability, pH tolerance, detergent/organic reagent tolerance, and reusability of spore-immobilized FAST-PETase were studied.The optimal reaction conditions for spore-immobilized FAST-PETase were 50 ℃ and pH 8.0.After incubation at temperatures ranging from 30 ℃ to 80 ℃ for 12 h, more than 82% of the original activity could be retained.Similarly, after incubation at pH 5.0-9.0 for 12 h, more than 78% of the original activity could be maintained.Compared with the free enzyme, spore-immobilized FAST-PETase also showed resistance to organic reagents, retaining 35% of its initial activity after seven reuse cycles.In this study, the immobilization of FAST-PETase was successfully realized by using the spore surface display system of S.cerevisiae and applied to the hydrolysis of BHET, providing a new platform for the long-term degradation of PET plastics.

L-asparaginase catalyze the hydrolysis of L-asparagine to produce L-aspartic acid, which can effectively inhibit the formation of acrylamide (class 2A carcinogen) in high-temperature food processing.Although type I L-asparaginase has good thermal stability, its catalytic activity still needs to be improved.This study aimed to improve the catalytic activity of Thermococcus zilligii type I L-asparaginase (TzI) through molecular modification.First, 10 TzI mutants with potential increased activity were screened using molecular docking and virtual saturation mutation, and their expression, purification, and enzymatic properties were analyzed.The results showed that the specific enzyme activity of mutant enzyme L265W reached 2 751.13 U/mg, 29% higher than the original enzyme TzI.Although the optimal reaction temperature was still 90 ℃, the half-lives of mutant enzyme L265W at 80, 85, and 90 ℃ were increased by 1.5, 1.56, and 1.43 times compared to TzI, respectively.Second, the potato chips were treated with an equal amount of enzyme under 80 ℃ blanching conditions, and the acrylamide content after frying was measured.The results showed that L265W can reduce acrylamide in fried French fries by 65%, which is better than the treatment with commercial enzymes and original enzyme TzI.Therefore, the mutated enzyme L265W constructed in this study has good potential for application, which will help promote the industrial application of L-asparaginase.

The mitogen-activated protein kinase (MAPK) cascade pathway extensively participates in the physiological regulation processes of plants.Trypsin, as an inducer of resistance, significantly enhances cucumber storage quality.However, the mechanism by which trypsin regulates the synthesis of phenylpropanoid compounds through the MAPK pathway to influence fruit resistance remains to be elucidated.To investigate the molecular mechanism underlying trypsin-induced cucumber resistance, this study conducted a combined transcriptomic and widely targeted metabolomic analysis, validated through virus-induced gene silencing (VIGS).Transcriptomic results revealed that a total of 83 differentially expressed genes were enriched in the MAPK pathway, with 48 genes significantly downregulated and 35 genes significantly upregulated.Gene set enrichment analysis (GSEA) further identified the CsWRKY33 transcription factor from the leading edge subset.Multiple sequence alignment results with plants such as Arabidopsis thaliana and Nicotiana tabacum showed that the transcription factor belonged to the WRKY family and had a highly conserved WRKY domain at the N-terminus.The combined analysis of transcriptomics and widely targeted metabolomics demonstrated significant upregulation in the synthesis of compounds such as vanillin, dihydrochalcone-4′-O-glucoside, and 2-hydroxy-3-phenylpropanoic acid.Co-expression network analysis suggested that these key metabolites were negatively regulated by CsWRKY33.VIGS results showed that silencing CsWRKY33 enhanced fruit resistance and extended storage time.This study revealed that trypsin could downregulate the expression of CsWRKY33, promoting the synthesis of compounds with high antioxidant and antibacterial activity, such as vanillin, dihydrochalcone-4′-O-glucoside, and 2-hydroxy-3-phenylpropanoic acid.This enhancement leads to increased fruit disease resistance and delayed senescence and decay.

Dextran is a glucose polymer linked by α-1,6 bonds.Different molecular weight dextrans have different applications.Dextran T2000 is a dextran with a heavy average molecular weight of around 2 MDa.It can be used as a food additive.T2000 is a high-end polysaccharide product.It can be used in medical testing to separate various types of proteins in blood.Currently, there are few reports on the enzymatic directed synthesis of dextran T2000.In this paper, the dextransucrase derived from Leuconostoc mesenteroides 0326 and the dextranase BMdex derived from Brevibacterium fuscum were linked by a linker.This study designed and constructed the specific fusion enzyme, achieving a one-step method for the direct preparation of dextran T2000.A fusion enzyme with dual enzyme activity was constructed and successfully expressed in Escherichia coli.The optimal pH and temperature for dextransucrase in the fusion enzyme were 5.5 and 30 ℃.The optimal pH and temperature for dextranase in the fusion enzyme were 9.0 and 50 ℃.0.1 g/mL sucrose solution was used as substrate and fusion enzyme with a final enzyme activity of 5 U/mL was added.The reaction was carried out at 25 ℃ for 24 hours at 120-180 r/min.The reaction solution was successfully isolated and purified to obtain dextran with a heavy average molecular mass of about 2 MDa.And the reaction yield could reach 32.6%.The results of the study provided a new pathway for the enzyme-directed preparation of high-molecular polysaccharides.

Cathartic colon is a type of laxative-dependent constipation accompanied by severe enteric nerve and intestinal barrier damage, and probiotic intervention is expected to be an effective treatment for it.In this study, an animal model of the cathartic colon was established using senna extract treatment to study the alleviating effect of Lacticaseibacillus paracasei CCFM1164 on the cathartic colon and to investigate its possible pathways.Results showed that L. paracasei CCFM1164 shortened the time to pass the first black stool and increased the number of fecal pellets within 5 h to relieve constipation in cathartic colon mice.The possible mechanisms underlying the alleviation of the cathartic colon were increasing the relative abundance of short-chain fatty acids (SCFAs)-producing bacteria, such as Lactobacillus and Marvinbryantia, to increase the content of SCFAs in the feces, enhancing the content of acetylcholine (ACh) in the colon, which in turn promotes the secretion of glial cell line-derived neurotrophic factor (GDNF) and thereby repairs the enteric nervous system, and further reducing intestinal inflammation and repairing the intestinal mechanical barrier.This study provides a theoretical basis for probiotics to relieve the cathartic colon.

To explore the alleviating effects and potential mechanisms of fermented soybean meal on colitis in mice, and seek an effective antibiotic alternative bio-feed, a dextran sulfate sodium-induced model of ulcerative colitis was employed, with treatment using fermented soybean meal by Lactobacillus plantarum DY6, to investigate the anti-inflammatory and intestinal mucosal repair capabilities.The results indicated that, both early intervention and treatment with the fermented feed significantly increased food intake and body weight of the mice, effectively reduced the mortality rate, and lowered the disease activity index scores compared to the model group.Moreover, it effectively facilitated the recovery of colonic structure from erosion, bleeding, and atrophy, significantly alleviated the increase in pro-inflammatory cytokines IL-6 and TNF-α levels, and markedly increased the expression level of closure protein in the tight junction of mouse colon tissue.The results suggested that fermented soybean meal can inhibit the signaling pathways leading to inflammation, mitigate the inflammatory response, and effectively protect the integrity of the intestinal mucosa, thereby alleviating colitis.This study provides theories and ideas for the prevention and control of animals colitis in the aquaculture industry, and is expected to develop a functional feed.

Chlorophyll could influence the structure of gut microflora induced with high-fat diet, alleviating obesity and improving inflammation, but the related effects still need further exploration.This research employed an in vitro anaerobic model to introduce pheophytins into the fecal microflora of mice which fed with high-fat diet, thereby delving deeper into the regulatory effect of pheophytins on the high fat diet induced microflora.After 48 hours of fermentation, we conducted the 16S rRNA microbiome, targeted metabolomics of short-chain fatty acids and untargeted metabolomics with ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry.The object was to examine the regulatory effects of pheophytin a and pheophorbide a on the microflora of the high fat diet induced mice.The results indicated that compared to the control group, the group treated with pheophytins could reduce the abundance of Proteobacteria at the phylum level and increase the abundance of Firmicutes.At the genus level, it significantly inhibited the abundance of the pathogen Escherichia-Shigella (P<0.05).The determination of short-chain fatty acids revealed that pheophytins could promote the high fat induced microflora to produce the short-chain fatty acids, of which acetic acid,propionic acid and butyric acid contents increased significantly (P＜0.05).Untargeted metabolomics analysis showed that extra pheophytins affected the high-fat diet induced microflora by producing lipoid substance, amino derivatives, bile acid salt and antibiotic substances (istamycin AO, fusidic acid, gentamicin C1…).Overall, pheophytins have the potential to regulate the structure and metabolism of high-fat diet induced microflora, with potential beneficial effects on overall health.

Lactobacillus rhamnosus MP108 is a probiotic strain that can be used in infant food.To verify whether it has a synergistic effect with oligosaccharides in immunomodulatory functions,an immunocompromised model was constructed using Wistar rats.The method was to use 40 mg/kg BW of cyclophosphamide injected intraperitoneally for three days after successful modeling, intervention was carried out using oligosaccharides and L.rhamnosus MP108.The recovery effect of their relevant physiological indexes was observed.The results showed that the MP108 group had the best regulation of splenic index, which was not significantly different from that of the drug used as a positive control (P>0.05), while 2′-FL helped to maintain thymic index.In terms of modulation of the ability to secrete TNF-α, the 2′-FL group, the compound + MP108 group and the 2′-FL + MP108 group, on the other hand, were not significantly different (P>0.05) from that of the positive control;In terms of IL-2 secretion ability, all groups except MP108 group had similar modulation effect as the positive control.The combination of oligosaccharides and probiotics had less effect on immunoglobulin secretion.In summary, L.rhamnosus MP108 and oligosaccharides have their own advantages in regulating the various indexes of immunocompromised rats, showing synergistic effects.

In this study, oyster peptides and anthocyanins were used as raw materials to explore the synergistic inhibitory effects of oyster peptides and anthocyanins against pancreatic lipase.Synergy Finder and Compusyn collaborative calculation models were used to analyze the synergistic effects of oyster peptides and anthocyanins at different ratios and the enzyme inhibition kinetics was used to explore the types of inhibition of pancreatic lipase by oyster peptides, anthocyanins, and their synergistic complexes.The multi-spectroscopy approach was used to investigate the interactions between oyster peptides and anthocyanins.Results showed that the half-maximal inhibitory concentration of oyster peptides and anthocyanins against pancreatic lipase were 1.35 and 3.54 mg/mL, respectively.When the concentrations of oyster peptides and anthocyanins were between 0.8 and 3.2 mg/mL, their highest single agent and zero interaction potency scores were 17.781 and 11.208, indicating strong synergistic effect existed between oyster peptides and anthocyanins.By calculating the combination index values of oyster peptides and anthocyanins at different concentration ratios, it was found that when oyster peptide∶anthocyanin=1∶1 (concentration ratio), their synergistic effect was the strongest.Enzyme inhibition kinetics results showed that oyster peptides, anthocyanins, and their synergistic complexes inhibited pancreatic lipase in a mixed inhibition and competitive inhibition manner.The multi-spectroscopy analysis showed that oyster peptides and anthocyanins form non-covalent complexes mainly through hydrogen bonds, hydrophobic interactions, and electrostatic interactions, which reduced the hydrophobicity and increased the polarity of the complexes.The above results indicated that oyster peptides and anthocyanins had good synergistic inhibitory effects against pancreatic lipase, providing a basis for in-depth research on their weight loss and lipid-lowering functional activities.

Copper ion concentration is a critical factor influencing the heterologous expression of CotA laccase in Escherichia coli.However, limited studies have focused on optimizing the fermentation conditions for the expression of recombinant bacterial laccase proteins in E.coli.The study investigated the effect of copper ion concentration on the expression levels of recombinant and mutant laccase in E.coli by controlling the amount of copper ion added during cultivation.The recombinant CotA laccase-expressing strain showed the highest laccase activity in cell lysate at a copper ion concentration of 1 mmol/L, reaching approximately 2 207 U/mL.The mutant laccase I421A-expressing strain exhibited maximum laccase activity at 1.5 mmol/L copper ion, reaching 631 U/mL.Similarly, the mutant laccase T466A-expressing strain reached the highest activity at 1.5 mmol/L copper ion, with 852 U/mL, and the K464A mutant strain showed the highest activity at 1 mmol/L copper ion, reaching 295 U/mL.The expression levels of these strains varied significantly with changes in copper ion concentration.The study provides valuable insights into improving the low expression levels of bacterial laccases by optimizing copper ion supplementation.

Kitchen waste is a major component of urban organic solid waste, characterized by high production volumes, rich organic matter content, and high bioavailability.In recent years, there has been increasing attention on using resource-recycling insects, such as Hermetia illucens L., to convert organic waste into valuable protein sources.However, further research is required to improve the absorption and conversion efficiency of H. illucens L.This study aimed to enhance insect protein synthesis from kitchen waste by pre-fermenting the waste with different combinations of probiotics.Results indicated that pre-fermentation using a combination of lactic acid bacteria, Bacillus subtilis, and yeast significantly increased the soluble protein content in kitchen waste, thereby promoting insect growth, development, and protein synthesis.Compared to the control group, biomass content increased by 74.7%, protein yield doubled (162.7 mg/g-TS), and the organic matter loss rate rose by 1.2 times (74.1%).Additionally, in comparison to the control group, the antioxidant activity of insect protein showed substantial improvement:1.16 times higher of total reducing power, 1.51 times higher of hydroxyl free radical scavenging activity, 1.24 times higher of DPPH free radical scavenging activity, and 1.14 times higher of ABTS cationic radical scavenging activity.The metal ion chelating ability also significantly improved by 1.21 times.These findings offer valuable insights for producing high-quality insect protein from kitchen waste.

Natto is a health food produced by the fermentation of Bacillus subtilis natto.In this study, orthogonal test was used to optimize the fermentation conditions of natto, and qRT-PCR was used to quantitatively analyze the expression of natto kinase gene aprN and ammonia producing gene rocG during fermentation.The results showed that during natto fermentation, the activity of natto kinase increased first and then decreased with time, temperature and amount of inoculation, and was greatly affected by temperature.Nattokinase activity reached 2 766.403 IU/mL under the conditions of 33 ℃, 24 h, 5%, and the expression of aprN gene was significant, while rocG gene expression was not. The fermentation conditions of 33 ℃, 24 h, 5% were determined as the optimal conditions for natto production.Natto with high nattokinase activity (2 766.403 IU/mL) and low ammonia could be obtained.This study can provide a reference for the quality control and commercial application of natto.

This study investigated the role of the Lactobacillus acidophilus L-55 in converting soy isoflavones into estrogen-like substances during the fermentation of soy milk.Sterilized soy milk was inoculated with the L-55 strain of L. acidophilus, as well as two other lactic acid bacteria extracted from commercially available yogurt (Streptococcus salivarius subsp. thermophilus and Lactobacillus delbrueckii subsp.bulgaricus), and cultured at 37 ℃ for 24 hours.At the end of the fermentation, the levels of four glycoside-type isoflavones, including daidzein, genistein, equol, and 5-hydroxy-equol, were measured using HPLC with internal standard methodology.Additionally, the genomic information of the L-55 strain was used to study gene clusters associated with the conversion of various estrogen-like substances.Results showed that the content of daidzein in soy yogurt fermented by the L-55 strain was 0.74 mg/100 mL, and the genistein content was 2.35 mg/100 mL, while these substances were not detected in significant amounts in soy yogurt fermented by the other two lactic acid bacteria.No substantial amounts of the estrogen-like substances equol and 5-hydroxy-equol were detected in any of the three soy yogurt samples.The total glycoside-type isoflavone content in soy yogurt fermented by the L-55 strain was 3.29 mg/100 mL, significantly higher than that in soy yogurt fermented by the other two strains.Genomic analysis revealed that the genome of the L-55 strain did not encode the genes for equol reductase and 5-hydroxy-equol reductase, consistent with the lack of significant detection of these two compounds in the samples.Furthermore, the accumulation of daidzein and genistein, important precursor substances for equol and 5-hydroxy-equol, was also confirmed due to the absence of these genes.In conclusion, since the L-55 strain can convert soy isoflavones into daidzein and genistein, it is possible to use this strain to produce soy yogurt containing estrogen-like substances (with estrogenic activity).

To improve the water resistance property of carboxymethyl chitosan (CMC) film, the CMC film was modified by Maillard reaction (MR) in this study.The effects of MR conditions on the water solubility of modified CMC films were studied.The relationship between MR degree and the performance and structure of CMC modified films were analyzed.The results indicated that the MR between CMC and reducing sugar can improve the water resistance property of CMC film, with xylose having the best modification effect.With the increase of xylose content, the water resistance properties of CMC modified films showed a trend of first increasing and then decreasing.The water resistance property of CMC modified film was best when the CMC/xylose ratio was 4∶1.The initial pH value of the film solution has no significant effect on the film water resistance properties.With the increase of reaction temperature and the extension of reaction time, the A₄₂₀ of the CMC modified films increased and its water resistance properties enhanced.The water resistance of CMC modified films was related to the MR degree.As the MR degree deepens, the color of CMC modified films deepened, the brightness decreased, the tensile strength, antioxidant and antibacterial activities increased, the transmittance and elongation at break decrease, the structure become denser, the crystallinity decreases, and the molecular interactions were enhanced.The results of this study provide a methodological reference for the application of CMC film in high moisture content foods.

This study used germinated kidney beans as the raw materials for the synergy treatment of monosodium glutamate (MSG) and low-temperature freeze-thaw, the glutamate decarboxylase (GAD), diamine oxidase (DAO), polyamine oxidase (PAO) activity before and after treatment were determined, and an untargeted metabolomics analysis was used to investigate the mechanism of γ-aminobutyric acid (GABA) enrichment in germinated kidney beans with synergy treatment of MSG and low-temperature free-thaw.Results showed that the synergy treatment of MSG and low-temperature freeze-thaw could promote GABA enrichment in germinated kidney beans, in which the GABA content was 3.33 times higher than that of germinated kidney beans only.Meanwhile, the synergy treatment of MSG and low-temperature freeze-thaw had no significant effect on GAD activity in germinated kidney beans, while decreasing DAO activity and PAO activity significantly.Untargeted metabolomics studies found that the synergy treatment of MSG and low temperature freeze-thaw could change the amino acids, lipids and carbohydrate metabolites in germinated kidney beans, indicating that GABA enrichment mainly by regulating the pathways of arginine and proline metabolism, β-alanine metabolism, nicotinate and nicotinamide metabolism, alanine, aspartate and glutamate metabolism, and butanoate metabolism.

Heavy metal pollution has become a major agriculturally environmental concern in China.Because of its wide range of pollution sources, long toxic residues, biological enrichment and difficult to degrade, it poses a great threat to the agricultural ecological environment, food security, and human health.In this work, based on the specific binding of biotin and streptavidin, the mercury ion (Hg²⁺) specific aptamer was modified on the agarose gel to fill the column to make a mercury ion aptamer affinity column.The efficient removal of mercury ions was achieved through high affinity and specificity of aptamer to the target.The maximum column capacity of this aptamer affinity column was 0.025 mg and showed good specificity to mercury ions, and could be reused at least 12 times.The column was further applied to the analysis of Hg²⁺in fish sauce samples with good removal and no obvious effects on its nutritional components.This method s achieves stable and efficient removal, and has the advantages of low cost and good development prospects.

To improve the extraction rate of soluble dietary fiber (SDF) from moso bamboo leaves, the extraction rates, structural and functional characteristics of soluble dietary fiber from bamboo leaves extracted by hot water extraction method, steam explosion method, sodium hexametaphosphate extraction method, and steam explosion-assisted sodium hexametaphosphate extraction method were compared and analyzed.Results showed that the extraction efficiency of the steam explosion-assisted sodium hexametaphosphate extraction method was the highest (51.15%), followed by the sodium hexametaphosphate method, steam explosion method, and hot water extraction method.The structure and composition of SDF were different between the steam explosion and the sodium hexametaphosphate explosion.The SDF with the combined method had the most complex structure, the smallest particle size and the highest absolute value of zeta-potential, which were 434.90 nm and -20.37 mV, respectively.The SDF extracted by the combined method had better functional properties and glucose adsorption capacity, cholesterol adsorption capacity, and ·OH radical scavenging capacity were the best, which were (52.04±0.19)%, (57.14±0.73)% (pH=2), (62.53±5.31)% (pH=7), and (95.50±1.46)%, respectively.The results provide a theoretical basis and data support for the extraction and application of soluble dietary fiber from moso bamboo leaves.

Radio frequency (RF) is a new heat treatment technology.By monitoring fat oxidation and structural changes of starch and protein during the storage of whole wheat flour at room temperature, this study investigated the effect of RF treatment on the physicochemical properties of whole wheat flour.The whole wheat flours were divided into three groups, including RF group, RF and deoxygenated group, and the untreated group, and were stored at room temperature for 6 months.After storage, the fatty acid value of RF group (50.89 mg/100 g) was a little lower than that of RF and deoxygenation group (52.18 mg/100 g) and much lower than that of untreated group (95.93 mg/100 g), while both the peroxide value and free radical intensity of RF and deoxygenation group were lowest, followed by RF group and untreated group.The starch crystallinity of the untreated group, RF group, and RF and deoxygenation group decreased by 4.59%, 2.94%, and 2.82%, respectively, and their free sulfhydryl content decreased by 18.29%, 8.33%, and 11.11%, respectively compared with the samples before storage.According to the results of changes in starch short-range ordering degree and thermodynamic properties, as well as changes in protein secondary structure and molecular weight distribution, it was found that the ordered structure of starch decreased and protein molecules aggregated after storage of whole wheat flour, while these changes in RF group were slower and were not different with that in RF and deoxygenation group.These results indicated that RF and deoxidization treatment could effectively inhibit the hydrolysis and oxidation of fat during the storage of whole wheat flour, and had little effect on the structure of starch and protein, thereby effectively improving the storage stability and quality of whole wheat flour and prolong its shelf life.

Zinc oxide nanoparticles (ZnO-NPs) can inhibit the growth and reproduction of microorganisms during maize storage, which is helpful for the safe storage of maize.In order to further clarify the effects of ZnO-NPs on grain cells and physiology during maize storage, different concentrations of ZnO-NPs were added during maize storage, and simulated storage at 30 ℃ for 42 days.The effects of maize grain cells and related physiological indicators were measured and analyzed.With the increase of storage time, compared with the control group (0 g/kg), the electrical conductivity of maize with 0.5 g/kg and 1.5 g/kg ZnO-NPs in the treatment group decreased by 1.72 μS/cm/g and 1.06 μS/cm/g, malondialdehyde decreased by 0.17 μmol/g and 0.08 μmol/g, POD activity increased by 5.1 U/g and 3.83 U/g, SOD activity increased by 0.69 U/g and 0.35 U/g, and H₂O₂ content decreased by 0.69 μmol/g and 0.42 μmol/g.The superoxide anion production rate decreased by 8.40 nmol/min·g and 5.32 nmol/min·g, and the zinc ion content did not change significantly compared with the control group.The results showed that the electrical conductivity, malondialdehyde, H₂O₂ content and superoxide anion production rate of maize with 0.5 g/kg and 1.5 g/kg ZnO-NPs addition were significantly lower than those of the control group, and POD activity and SOD activity were significantly higher than those of the control group.The color and cell structure of maize remained good, indicating that the addition of low concentration (0.5 g/kg and 1.5 g/kg) ZnO-NPs alleviated the deterioration of cell quality and helped to protect the structure and physiological activity of maize cells.This study provides basic data for the further development and application of zinc oxide nano-antibacterial particles.

With the interaction of catechins and potato starch, the effects of different amounts of catechins on the microstructure, particle size, whiteness, infrared, gelatinization and rheological characteristics of potato starch were studied under specific toughness treatment conditions.The results showed that the addition of catechin did not change the integrity of potato starch granules, but increased the average particle size of potato starch granules.Infrared analysis showed that the addition of catechin under toughness treatment did not produce new peaks, but the starch gelation and shear resistance were reduced.Rheological analysis found that the samples were non-Newtonian fluid and showed pseudoplastic and shear thinning, and the toughness treatment strengthened the gel structure of starch paste, while the addition of catechins weakened the gel structure of starch and the added amount of starch would also affect the gel structure of starch and the elasticity of the gel system.It not only expanded the application prospect of potato starch, promoted the development of related industries, but also provided more possibilities for product innovation and technological progress.

From thyme essential oil, oregano essential oil, cinnamon essential oil, clove essential oil and Litsea cubeba essential oil, a plant essential oil with the strongest inhibition effect on Cladosporium coriolis, Penicillium christenseniae, Penicillium tropical penicillium and Aspergillus flavus was selected, and phase transition method was adopted.Using Tween 80 as surfactant and anhydrous ethanol as cosurfactant, a clear and transparent nano-emulsion of cinnamon essential oil was prepared by means of adding water by observing the stratified volume of liquid and determining the surfactant and cosurfactant ratio value, and its antibacterial mechanism and fresh-keeping effect on fresh-cut purple potato were studied.Results showed that cinnamon essential oil had the strongest inhibitory ability against the dominant putrefaction of purple potato.The cinnamon essential oil nanoemulsion could reduce the surface hydrophobicity of the cell membrane, increase the permeability of cell membrane, and effectively inactivate the dominant putrefaction of purple potato.The fresh cut purple potato was treated with cinnamon essential oil nanoemulsion, the putrefaction rate was significantly reduced, water retention was effective, and the storage period could be extended for 6 days. After 12 days of storage, weight loss decreased by 7.08%, browning degree decreased by 37.19%, polyphenol oxidase activity decreased by 83.85% and peroxidase activity decreased by 84.96%, which delayed the browning of cut surface and tissue aging process, and achieved the role of fresh-cut purple potato preservation.

Based on the rye noodles, the effects of different microwave power, loading capacity, and noodle thickness on drying characteristics and the effective moisture diffusion coefficient of rye noodles were studied by using the microwave intermittent drying method.The intermittent microwave drying kinetics model of rye noodles was obtained by fitting five drying kinetics models with SPSS software.The quality evaluation of microwave-dried rye noodles was carried out.Results showed that the microwave intermittent drying of rye noodles was mainly reduced speed drying.The drying speed was faster and the drying time was shorter when the microwave power was higher, the loading capacity was smaller and the thickness was thinner.During the drying process, the effective moisture diffusion coefficient ranged between 1.180 39×10^-11 and 2.967 02×10^-11m²/s, and increased with the increase of microwave power and wall thickness, but decreased with the increase of loading capacity.Through model fitting, the Logarithmic model was the best model for intermittent microwave drying of rye noodles, with the largest R² and the smallest χ² and RMSE, which could effectively describe the change of water content during microwave drying of rye noodles.The microwave-dried rye noodles had a good black-red shiny color, high bending resistance, 0 cooked broken rate, 7.70% of cooking loss rate, good texture characteristics, and commercial value.This study provides a theoretical basis for the application of microwave technology in noodle production.

Sodium nitrite, as a food additive, is internationally recognized as a first-class carcinogen.To investigate the effect of a high-voltage pulsed electric field on the adsorption characteristics of sodium nitrite on wheat bran, a high-voltage pulsed electric field was used to treat wheat bran, and the kinetics and thermodynamic characteristics of wheat bran adsorption of sodium nitrite were analyzed.Results showed that the adsorption of sodium nitrite by wheat bran reached adsorption equilibrium after 120 minutes, and the pseudo-second-order kinetic equation and Freundlich model could better describe the adsorption process, indicating that the adsorption process involved both physical and chemical adsorption.The reaction of wheat bran adsorbing sodium nitrite was non-spontaneous, and increasing temperature increased the adsorption quantity and rate of wheat bran for nitrite, which promoted the adsorption quantity of wheat bran for sodium nitrite.As the electric field strength increased from 10 kV/cm to 40 kV/cm, the adsorption quantity and rate of wheat bran for sodium nitrite increased by 10.91% and 12.82%, respectively.However, when the electric field strength increased from 40 kV/cm to 50 kV/cm, the adsorption quantity and rate of wheat bran for sodium nitrite decreased by 7.46% and 16.45%, respectively.Therefore, the pulsed electric field of 40 kV/cm can be applied to improve the adsorption capacity of wheat bran for sodium nitrite, and the result can provide theoretical guidance for the comprehensive utilization of wheat bran.

With the increasing awareness of green environmental protection, food packaging with degradable plant fiber/polymer composite materials has been widely concerned.However, the interfacial incompatibility between hydrophilic bamboo fiber (BF) and hydrophobic polylactic acid (PLA) weakens the mechanical strengthening effect of BF in composite materials, making the regulation of interfacial properties crucial.Firstly, the effect of BF modified by graphene oxide (GO) on the properties of PLA-matrix composites were investigated.Subsequently, the PLA-based composite material was used as a strawberry tray packaging to explore its influence on the storage quality of strawberries.It was found that the addition of fiber could improve the modulus of the composite, and the improvement effect of GOBF/PLA was the most significant (compared with pure PLA, the bending and tensile modulus of GOBF/PLA were increased by 16.39% and 35.90%, respectively).GOBF/PLA had higher glass transition temperature and better interface bonding performance.Compared to BF, GOBF possessed stronger heterogeneous nucleation capability resulting in lower cold crystallization temperature values and higher crystallinity values for GOBF/PLA.The SEM analysis revealed that the cross-section after bending failure of BF/PLA exhibited numerous holes and micro-cracks;conversely, GOBF/PLA displayed fewer micro-cracks.The addition of hydrophilic fiber reduced the strength and hydrophobicity of the composite, but the effect of GOBF on the strength and hydrophobicity of the composite was less than that of BF.The results of strawberry storage showed that GOBF/PLA could significantly reduce the decay rate of strawberry fruits and delay the decrease of titrable acid content in strawberry fruits at the later stage of storage, which had better fresh-keeping effect on strawberry fruits.In conclusion, this study can provide reference for the development and application of disposable green fruit and vegetable trays.

This study used the wall-breaking machine, colloid mill, and wet ultrafine pulverizer combined with the composite enzyme method to prepare blueberry juice.The effects of different grinding methods on the processing characteristics, active substance content, and antioxidant activity of blueberry juice were analyzed, and metabolomics was used to analyze the differential metabolites in blueberry juice.Results showed that there was no significant difference in the yield of blueberry juice under different grinding methods (P>0.05), but the wet ultrafine grinding group had the smallest average pulp particle size (64.26 μm), and the highest content of anthocyanins, total flavonoids, and total phenols (613.64 mg/L, 2.94 g/L, 3.46 g/L, respectively).The scavenging rates of DPPH free radical, ABTS cationic radical, and ·OH free radical of blueberry juice in the wet ultrafine grinding group were significantly higher than those in the wall breaking group and colloid grinding group (P<0.05), with values of 92.31%, 85.29%, and 71.76%, respectively.The expression trends of differential metabolites in blueberry juice under different grinding methods were consistent with the changes in active substance content and antioxidant activity.Among them, the expression levels of daidzein, anthocyanins, quercetin, and their isomers in blueberry juice in the wet ultrafine grinding group were significantly upregulated, which was speculated to be the fundamental reason for its strong antioxidant activity.This result can provide a theoretical basis for expanding the application of wet ultrafine grinding technology and preparing high-quality and high-nutrition blueberry juice.

The goals of this study was to optimize gibberellin acid (GA₃) treatment measure on Thompson Seedless, and to improve the quality of grapes and raisins.This study taken Thompson Seedless grape as material, the experiment consisted of five treatments no treatment during bloom +150 mg/L GA₃, 10 days post-bloom, 75 mg/L GA₃, 75% bloom +150 mg/L GA₃, 10 days post-bloom, 75 mg/L GA₃, 100% bloom +150 mg/L GA₃, 10 days post-bloom, 75 mg/L GA₃, 2 days post-bloom +150 mg/L GA₃, 10 days post-bloom, 75 mg/L GA₃, 4 days post-bloom +150 mg/L GA₃, 10 days post-bloom, no spraying (bloom and post-bloom) was the control, berries quality, raisin quality, and yield were assessed.The results showed that cluster weight, berry weight, shape index, berry hardness and vitamin C content increased with GA3 treatment, promotes the color to green.The L^* and a^* value of raisin were decreased with GA₃ treatment, raisins lost brightness and turned green.The yields of grape and raisin were the highest in (75 mg/L GA₃, 2 days post-bloom +150 mg/L GA₃, 10 days post-bloom) treatment, with 74.10 t/hm²and 17.33 t/hm², respectively, single raisin weight and raisin shape index were also the highest in (75 mg/L GA₃, 2 days post-bloom +150 mg/L GA₃, 10 days post-bloom) treatment, 1.20 g and 2.96, respectively, phenolic substances and antioxidant activity were relatively high.The results of principal component analysis directly reflected the quality distribution of berries and raisins in each treatment, (75 mg/L GA₃, 2 days post-bloom +150 mg/L GA₃, 10 days post-bloom) had the highest comprehensive score by comprehensive evaluation model, and the effect on Thompson Seedless with (75 mg/L GA₃, 2 days post-bloom + 150 mg/L GA₃, 10 days post-bloom) was the best.

To investigate the differences in physicochemical properties and volatile components of Liguang preserved apricot under different processing conditions, sensory evaluation, browning degree, total sugar, titratable acid, and volatile component determination were performed on the traditional process of hot air-dried apricot (HAD), boiled sugar with apricot (BSW), and non-heat treated apricot (WMD) using headspace solid-phase microextraction and gas chromatography-mass spectrometry.The research results indicated that the highest browning degree of HAD was 0.66, and the lowest browning degree of BSW was 0.26.The lowest total sugar content treated with WMD was 42.36%, and the titratable acid content was 1.03%.WMD effectively reduced the sugar content and alleviated the problem of sweet and greasy taste in preserved fruit products.Fresh fruits were used as a comparison in HS-SPME-GCMS detection, and 6 groups were taken from each of the four samples for parallel testing.A total of 88 volatile components were detected, mainly including 19 alcohols, 20 aldehydes, 13 ketones, 9 esters, 16 terpenes, 3 acidic substances, and 8 other types.The key differential aroma components of four types of samples were determined using correlation odor activity value (ROAV) combined with orthogonal partial least squares discriminant analysis (OPLS-DA).The key aroma components extracted by HAD were furan, biphenyl, and 3-furfural.The key aroma components of BSW were linalool, hexanal, and cis geraniol.The key aroma components of WMD were hexanal, linalool, and 3-octanol.This result provides a scientific basis for further elucidating the differences in physicochemical properties and flavor compounds of apricot preserves treated with different techniques, and for the rational development of related products, by measuring the physicochemical indicators of three different processing techniques of apricot preserves and comparing them with the volatile components of fresh fruits.

In order to investigate the impact of drying methods on bioactive components and anti-inflammatory activity of Siraitia grosvenorii, mature fruits were dried by freeze-drying, microwave-drying and hot-air drying (70 and 100 ℃), respectively.The functional components including total sugars, total flavonoids, total saponins and characteristic mogrosides such as mogroside V, 11-oxo-mogroside V, siamenoside I, mogroside IV, mogroside IIIE and mogroside IIE in the dried samples were quantified through phenol-sulfuric acid, aluminum nitrate colorimetry and high-performance liquid chromatography methods.Furthermore, the lipopolysaccharide-induced RAW 264.7 cell model was adopted to assess their anti-inflammatory activities in vitro.Results indicated that the species and relative contents of mogrosides significantly varied during the drying process, the content of total flavonoids notably increased, but the content of total sugars decreased with the increase of drying temperature.Correlation analysis showed that contents of total saponins, 11-oxo-mogroside V and secondary glycosides were positive correlated with anti-inflammatory activity.It was obvious that total saponins content and total flavonoids content showed positive correlation with NO inhibitory activity, while total sugars was negative correlated with reactive oxygen species inhibitory activity.These findings suggested that drying methods influence the functional components and anti-inflammatory activity of S. grosvenorii, particularly the species and contents of mogrosides and flavonoids, and hot-air drying was conducive to the enhancement of anti-inflammatory activity.

To analyze the flavor compounds and sensory characteristics of Moldova wines from different regions, we examined physical-chemical indexes, chromaticity, organic acids, polyphenol, mono-Phenol, anthocyanin, volatile compounds, and sensory evaluation of Moldova wines from three regions of Shaanxi province.The results showed that Moldova wines were reddish or ruby red in color, had a low alcohol concentration, low color brightness, and high saturation.The key indicators that set Moldova wines apart from those of Weibei Dry Plain and Southern Shaanxi were anthocyanins and flavanols.In three-region differentiation, the mono-phenol content-based PLS-DA model performed the best.Of the 162 volatile compounds detected, 34 had an odor activity value greater than 1.Key volatile substances that affect the aroma characteristics of Shaanxi included (E)-1-(2,6,6-trimethyl-1,3-cyclohexadien-1-yl)-2-buten-1-one, ethyl acetate, ethyl hexanoate, 1-hexanol, and octanoic acid, which brought a sweet, fruity, herbal, and fatty aroma.Weibei Dry Plain Moldova wine was recognized for its distinctive fragrance compounds, which included ethyl butyrate, ethyl isobutyrate, 2, 3-butanedione, and dodecanal.Guanzhong Plain’s core odor component was ethyl 3-phenylpropionate.And the distinctive scent compounds in Southern Shaanxi were 1-heptanol and 1-pentanol.Furthermore, the comprehensive sensory score was Weibei Dry Plain > Southern Shaanxi > Guanzhong Plain.

This study investigated microbial diversity, flavor compound changes, and the contribution of dominant microbial genera to key metabolic pathways during highland barley wine fermentation.The macro-genome sequencing technology and solid-phase microextraction gas chromatography were utilized to analyze the process.The main dominant bacteria identified were Lactobacillus, Rhizopus, Wickerhamomyces, and Pichia.A total of 37 flavor substances, including 13 esters, 15 alcohols, 4 aldehydes, 2 ketones, 2 phenols, and 1 pyrazine, were detected.Metagenomic sequencing yielded 8 230 72 genes, and 5 microbial species for KEGG gene function were annotated.Notably, global and overview maps revealed high relative abundance in carbohydrate metabolism, signal transduction, energy metabolism, and amino acid metabolism.Furthermore, the distribution of different microorganisms in substrate metabolism networks and flavor formation varied.Lactobacillus, Pediococcus, Rhizopus, Saccharomyces, and Pichia were predicted to play significant roles in flavor formation.This study sheds light on the metabolic effects of diverse microorganisms during highland barley wine fermentation.

This study investigated the composition, content, and potential value of diverse terpenoids in Jingjiu based on solvent-assisted flavor evaporation (SAFE) and GC-MS techniques.Volatile components of Jingjiu were extracted and non-volatile components were removed using liquid-liquid extraction combined with SAFE.The concentrated extracts were then subjected to GC-MS analysis.The experimental conditions for liquid-liquid extraction and SAFE were optimized.By utilizing spectral library retrieval and retention index comparisons, a total of 71 terpenoid compounds were identified in Jingjiu, including 29 monoterpenes and 42 sesquiterpenes.Quantitative analysis revealed that the predominant terpenoid compounds in Jingjiu were the monoterpenes, including bornyl acetate[(17 222.4±335.2) μg/L] and (+)-2-bornanone[(10 920.8±225.1) μg/L].Both of these compounds imparted a refreshing pine aroma and possess antimicrobial, anti-inflammatory, and analgesic properties.The sesquiterpenes exhibited structural complexity and many of their oxygenated derivatives demonstrated significant biological activity.Among them, the sesquiterpenes calamenene[(237.09±6.11) μg/L] and α-cadinol[(236.2±20.3) μg/L] showed potential anti-cancer properties, while α-calacorene[(172.49±3.71) μg/L] exhibited anti-inflammatory and bronchodilatory effects.These compounds significantly contribute to the distinctive flavor and functionality of Jingjiu, offering novel insights and directions for the study of functional factors in Jingjiu.

To assess the various packaging barrier properties denoted as S1(L), S2(M), and S3(H) on quality differences of fresh-cut pineapple during storage, physicochemical properties and flavor substances were monitored at 4 ℃.Additionally, the relationship between the concentration of flavor substances and packaging barrier properties was investigated by odor threshold (OT) and odor active value (OAV).The findings indicated that S2(M) effectively curbed weight loss and increased aerobic plate count, postponed declines in fruit firmness, ascorbic acid content, and total phenol content, and minimized tissue browning.Besides, esters were the primary flavor substances with an oxygen-dependent effect, while alcohols and acids were the main off-odor compounds with a positive correlation with packaging barrier properties.A total of 26 flavor substances with an OAV≥1 were identified, of which methyl acrylate, ethyl butyrate, ethyl valerate, methyl hexanoate, ethyl hexanoate, methyl 3-methylthiopropionate, and methyl caprylate were significantly correlated with packaging barrier properties (P<0.05).High-barrier packaging not only inhibited the synthesis of the characteristic aroma substances but also promoted the formation of off-flavor compounds in fresh-cut pineapple.S2(M) exhibited optimal performance in preserving the quality of fresh-cut pineapple, attributed to its well-suited packaging barrier properties.

The impact of natural shade drying, natural sun drying, hot air drying (HD), and vacuum freeze drying (VFD) on the quality and flavour of Zanthoxylum armatum DC was investigated.The findings revealed that the quality of vine pepper subjected to VFD was superior to that of the other three drying methods in terms of colour, lustre, sanction content, and other characteristics.The moisture content of peppers treated with HD was marginally higher than that of the other three treatments.Among all the drying methods of Z. armatum DC, HD-treated peppers exhibited the greatest diversity of flavouring substances, with a total of 38, while VFD-treated peppers demonstrated the highest concentration.The content of flavouring substances was found to be 2 235.407 mg/mL. A partial least squares discriminant analysis model was established based on the flavour substances, and the variable importance in projection value was calculated to identify 22 key flavour differentiating substances of Z. armatum DC that were significantly affected by different drying methods.These were the enol ketones such as pinacol, hinokitone, 4-terpene alcohol, and α-pinacol.The findings of the study indicated that the comprehensive utilization of VFD in the drying process yields superior outcomes in terms of colour, moisture content, and the retention of flavour substances in fresh Z. armatum DC.The results of this study offer a valuable data-driven foundation for the selection and application of fresh Z. armatum DC drying technology.

Collagen is a kind of spiral fibrous protein that is the main component of connective tissue in animals and polysaccharide is a kind of carbohydrate substance with complex molecular structure, which is widely distributed in nature.They can form collagen and polysaccharides complexes through covalent and non-covalent interactions, which have an important impact on the microstructure and functional properties of collagen, and significantly affect the application of collagen in the food industry.Based on the introduction of the interaction mechanism and regulation methods of collagen-polysaccharide complex, this paper reviewed the effects of collagen-polysaccharide interaction on the microstructure and functional properties of collagen, as well as the application of collagen-polysaccharide complex in food, to provide certain references for the application of collagen-polysaccharide complex in food industry.

As a high-quality natural plant protein resource, soybean protein not only contains good nutritional value but also possesses unique functional characteristics.As an important functional property of soybean protein, gelation has attracted much attention, but the natural gel products made from soybean protein have the problems of poor stability and low mechanical strength, which limits the application and development of this kind of gel products.Therefore, it is crucial to improve gel properties of the soybean protein products to meet the diversified needs of the market.In this review, the effects of physical modification, enzyme modification, and physical-enzyme coupling modification on the properties of soybean protein gel were reviewed, the internal relationship between different modification methods and “processing parameters-protein structure-product properties” of soybean protein gel was summarized, and the mechanism behind the effect of physical-enzyme coupling modification on the properties of soybean protein gel was clarified.Hence, this study provides a theoretical basis and technical support for the development of high-quality soybean protein gel products.

Deep eutectic solvent (DES), emerging as a novel generation of green solvents, due to their simple preparation process, minimal toxicity, biodegradability, and other advantageous characteristics, can overcome the limitations of traditional organic solvents.Consequently, DES serve as excellent alternatives to conventional organic reagents.This paper presents a comprehensive review of the most recent research findings in the field of DES, including the composition categorization, preparation techniques, performance parameters, and its advancements in natural product extraction, food testing and analysis, as well as catalytic reaction media.This review summarizes the concerned issues currently associated with DES, while also prognosticating potential future applications.This work offers a valuable reference for further exploration of the biochemical characteristics of green solvent systems and their practical applications.

Ginseng is a valuable Chinese herbal medicine, and rare ginsenosides are the most effective functional components in ginseng.The preparation of rare ginsenosides by biotransformation has become a research hotspot.Ginsenoside compound K (ginsenoside CK) has the capacity to be anti-tumor, anti-inflammatory, anti-aging skin, anti-diabetes, anti-depression, and anti-osteoporosis agents, while maintains other beneficial biological properties.In this paper, the methods suitable for large-scale preparation of ginsenoside CK and its biological activity were systematically reviewed to provide reference for the massive production of ginsenoside CK and further exploration of its pharmacological mechanism.

Green tea is one of the six major types of tea that enjoy widespread consumer popularity.Amino acids are key flavor constituents that significantly influence the quality of green tea.The processing technology is closely related to the synthesis and transformation of amino acids and the formation of flavor quality of green tea.The present review provided a comprehensive overview of the advancements in green tea amino acid synthesis and metabolism, elucidated the correlation between amino acids and flavor attributes such as taste, aroma, and color in green tea, and elaborated on the latest research progress of the effects of processing technology such as spreading, fixation, shaping, and drying on the metabolism of green tea amino acids and the formation of flavor quality in recent years.Finally, this study provided a forward-looking perspective on the future research directions concerning the regulation of amino acids in green tea.This paper provides a reference for the targeted and precise processing of high-quality green tea.

Melatonin is a kind of indole amine tryptamine compound widely existing in fruits and vegetables, which has physiological effects such as regulating fruits and vegetables ripening and senescence, scavenging reactive oxygen species, and enhancing biotic and abiotic stress resistance.It is a natural, efficient, and safe fresh-keeping agent for fruits and vegetables.Studies demonstrate that melatonin plays a significant regulatory role in reducing the chilling injury of postharvest fruits and vegetables.In this paper, the mechanisms of melatonin treatment to reduce chilling injury of postharvest fruits and vegetables were reviewed in detail from the aspects of cell membrane structure and function, antioxidant system, energy metabolism, proline metabolism, and sugar metabolism, and the factors influencing melatonin treatment to alleviate postharvest fruit and vegetable chilling injury were discussed, which could provide a reference for the application of melatonin in the control of chilling injury of postharvest fruits and vegetables.

Corn silk is widely used in functional foods, and polysaccharides is an important active ingredient in corn silk.In recent years, an increasing number of studies have been conducted on corn silk polysaccharides.Corn silk polysaccharides is a rich and pharmacologically important biomolecule in corn silk, and numerous studies have shown that corn silk polysaccharides have various biological activities, such as antioxidant, hypoglycemic, hypolipidemic, hepatorenal protective activities, antitumor, anti-fatigue, immunomodulation, etc. In this paper, the extraction, purification, structural characterization, biological activity, toxicity, and possible active mechanism of maize whisk polysaccharide were reviewed.It provides theoretical basis for further research and development of maize polysaccharide.