This study was performed to investigate the inhibitory mechanisms of 3 plant polyphenols, grape seed extract (GSE), lotus seed proanthocyanidins (LSPC) and lotus root polyphenol extract (LRPE), against Shewanella putrefaciens. Their antibacterial effects were determined in terms of minimum inhibitory concentration (MIC) and the growth curve of S. putrefaciens. By scanning electron microscopy (SEM), relative conductivity, propyridine iodide (PI) staining, alkaline phosphatase (AKP) activity, extracellular protein content, nucleic acid leakage, Na+ K+ -ATPase activity and membrane protein fluorescence analysis, the antibacterial mechanism was explored. The results showed that the MICs of GSE, LRPE and LSPC were 31.25, 62.25 and 125.00 μg/mL, respectively. After S. putrefaciens was treated with the polyphenols, the position of membrane proteins was changed, the fluorescence intensity was reduced, the morphology was altered, the surface became wrinkled and sunken, and the growth was significantly inhibited. In addition, the activity of extracellular AKP, the contents of nucleic acid and extracellular protein in the bacterial suspension, relative conductivity and PI intake were significantly increased, and Na+ K+-ATPase was inactivated to a certain extent, thereby leading to cell death.

The effect of nanosized bamboo dietary fiber (NBDF) on whey syneresis in yogurt during shelf storage was studied. The milk wettability of micro- and nano-modified NBDF with different particle sizes was analyzed. The inhibitory mechanism of the modified NBDF exhibiting the best milk wettability on whey syneresis during the shelf storage of yogurt was investigated. The results showed that the morphology of NBDF changed from blocky to filamentous after sequential ultrasound, pressurized heating and enzymatic hydrolysis. The microfibrils were fractured after high-energy mechanical ball milling, forming nanoclusters. The milk wettability of modified NBDF initially increased and then decreased with the decrease in particle size. The microfibrils with a particle size of 10–30 μm had the strongest milk wettability. Addition of the microfibrils at a mass concentration of 9 g/L improved the oscillation stability of set yogurt. After 28 days of shelf storage, the whey separation rate was 5.84%, which was only 57.87% of that of the control group. This may be related to the fact that the microfibrils effectively increased the proportion of bound water in yogurt (by 41.4%), improved the casein network structure, and increased the coatability, contributing to the formation of tiny and uniform whey pore channels in yogurt.

In order to enhance the photodynamic inactivation (PDI) effect of curcumin, a novel class of halogenated curcumin derivatives X-cur (X = F, Cl or Br) was synthesized and screened for its potential for PDI by ultraviolet-visible (UV-Vis) absorption and fluorescence spectroscopy, singlet oxygen (1O2) generation capacity and theoretical calculations of excited states. The results demonstrated that as the relative molecular mass of the nonmetallic heavy atom halogen increased, the spin-spin coupling effect was gradually strengthened, so the smallest energy level difference (ΔEst(S1-T3)) between singlet excited state (S1) and triplet excited state (T3) (0.140 eV) and the highest spin-orbit coupling value (0.642 262 cm-1) were observed in Br-cur. This finding suggested that Br-cur was most likely to undergo transition into triplet state through intersystem crossing. Furthermore, compared to curcumin and other halogenated curcumins, Br-cur exhibited the smallest energy level difference (3.260 eV) between its S1 and ground state (S0) . Due to the aforementioned factors, Br-cur was highly prone to photooxidation and had the highest 1O2 generation capacity. Br-cur had a PDI effect on Vibrio parahaemolyticus, a prevalent foodborne pathogen in aquatic products, which depended on its concentration and light exposure duration and was significantly higher than that of curcumin. Thus, Br-cur has great potential for application as a novel PDI agent.

In order to explore the pork spoilage potential of Pseudomonas fragi and the antibacterial mechanism of garlic essential oil, P. fragi was isolated from chilled pork under aerobic storage conditions and tested its spoilage capacity. The isolates with strong spoilage capacity were selected for further investigation. The antibacterial activity of garlic essential oil against the selected strains was evaluated by determining the minimum inhibitory concentration (MIC) and plotting the bacterial growth curve. Furthermore, the antibacterial mechanism was investigated by scanning electron microscopic (SEM) observation as well as measuring cell membrane permeability, bacterial motility and metabolic activity. The results showed that P. fragi could cause pork spoilage. Garlic essential oil exhibited a strong inhibitory effect against P. fragi derived from pork, with a MIC of 0.125 μL/mL. Garlic essential oil could disrupt the normal structural morphology of P. fragi, enhance the permeability of the cell membrane, and inhibit bacterial metabolic activity and mobility. The results from this study can provide a theoretical foundation for the application of garlic essential oil as a natural food preservative.

This study evaluated the conformational changes of polyphenol oxidase (PPO) in the crystalline solid (C-) and liquid (L-) states at room temperature (298.15 K) and normal or ultra-high pressure (0.1-400.0 MPa). The results indicated that when the pressure increased from 0.1 to 400.0 MPa, the spatial structure of PPO in both states became unstable. Compared with L-PPO, C-PPO was more susceptible to pressure, and exhibited higher residue fluctuations, reduced solvent accessible surface area and volume and a denser structure. With the transition of α-helices to random coils under high pressure conditions, the number of hydrogen bonds became unstable and α-helix elasticity decreased, thus leading to significant conformational differences. The active site of the Cu2+ position was displaced, the inter-residue distance was altered and random motion appeared, thereby interfering with substrate binding. In conclusion, both physical state and pressure level can influence PPO’s spatial structure, residue mobility, and substrate binding range, ultimately impacting the enzyme’s stability, and their impacts on the degree of enzyme denaturation can be ranked as follows: solid state > liquid state, and physical state > pressure level.

The perception of fat-related sensory attributes in food emulsions during oral processing mainly depends on the complex interactions between the emulsion droplets and the oral soft surface as well as saliva. A range of surface behaviors including adhesion, wetting, and spreading of emulsion droplets on the tongue surface influence the frictional and lubricative properties of emulsions. In this study, the effect of oil droplet size, applied normal load, and saliva addition on the tribological properties of an oil-in-water (O/W) emulsion prepared using microfluidized pea protein isolate (PPI) as an emulsifier. The results showed that with increasing applied normal load (0.5-2.0 N), the friction coefficient of the emulsion decreased obviously. With the decrease in droplet size, the number of droplets available for entrainment increased, resulting in a decrease in friction coefficient (10%-30%) and a decrease in boundary regime range of 15%-20% and thus enabling lubrication at lower entrainment speeds. During simulated oral processing, addition of saliva induced the flocculation of droplets, increasing droplet size, preventing droplets from being entrained into the oral surface, and ultimately resulting in a higher friction coefficient for the emulsion. This study can provide technical support for regulating the oral texture sensory properties of pea protein-based emulsion and the development of plant-based products.

In order to improve the stability and functional properties of casein-derived bioactive peptides (CP) in yogurt, the peptides were microencapsulated using sodium alginate and sucrose fatty acid esters as the wall material, which was determined based on encapsulation efficiency and peptide loading, and the developed microcapsules were applied in yogurt. Scanning electronic microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) proved the successful encapsulation of the peptides. The microcapsules had good sustained release properties, and the release rate was (62.57 ± 1.17)% after 3 h of intestinal digestion. The microencapsulated bioactive peptides improved the water-holding capacity, hardness and viscosity of yogurt, and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability of yogurt with the bioactive peptides was (63.73 ± 1.97)%. The microencapsulated bioactive peptides were not degraded during yogurt fermentation by lactic acid bacteria, and the functional properties of yogurt were enhanced by addition of the bioactive peptides.

Artemisia sphaerocephala Krasch. polysaccharide (ASKP) is a novel plant polysaccharide. In this study, an aqueous two-phase system (ATPS) consisting of gelatin (Gel) as the dispersed phase and ASKP 60P (a high-molecular-mass fraction of ASKP) as the continuous phase was constructed based on the thermodynamic incompatibility between 60P and Gel at a specific pH, and Gel/60P ATPS emulsion gels were obtained by introducing Fe3+ into the ATPS in order to induce 60P cross-linking. The results showed that the ATPS, consisting of 0.1%–0.5% Gel and 0.5%–1.5% 60P (m/m), exhibited discrete phase separation. The emulsion gel with 0.6% Gel, 1.5% 60P and 60 mmol/L Fe3+ showed good gel strength and elasticity. This was attributed to the fact that the increase in Gel concentration led to a decrease in the volume proportion of the continuous phase, resulting in exposure of more Fe3+ crosslinking sites, enhancing the interaction between 60P and Fe3+, and improving the mechanical properties of emulsion gels. Therefore, this study proposes a new strategy to improve the properties of ASKP gels, which is favorable for the wide application of ASKP in the food, biological and other fields.

The gene (PsHex) encoding β-N-acetylglucosaminidase from the marine bacterium Pseudoalteromonas sp. DL-6 was cloned into the pET-28a(+) vector and then successfully heterologously expressed in Escherichia coli BL21(DE3). The expressed protein was purified through nickel-nitrilotriacetic acid affinity chromatography. The results showed that PsHex encoded 876 amino acids, and the predicted molecular mass and pI were 99.46 kD and 5.65, respectively. Phylogenetic analysis and multiple sequence alignments showed that PsHex belonged to the glycosyl hydrolase 20 (GH20) family. The optimal temperature and pH for the recombinant enzyme were 30 ℃ and 8.5, respectively, its specific activity was 11.30 U/mg and it displayed the highest stability at 20 ℃ and pH 7.5. This enzyme could degrade various substrates, including agarose, chitosan, soluble starch and carrageenan and could be activated by metal ions (Na+, Mg2+, Fe3+, K+, and Ca2+), DL-dithiothreitol, tween-80, ethylenediaminetetraacetic acid and β-mercaptoethanol. The Michaelis constant (Km), catalytic rate constant (Kcat), maximum reaction rate (vmax) and Kcat/Km values toward the substrate 4-nitrophenyl 2-acetamido-2-deoxy-β-d-glucopyranoside were 2.523 mol/L, 79.035 min-1, 2.081 U/mg and 31.326, respectively. This study provides a theoretical reference for the enzymatic degradation of chitin to produce N-acetylglucosamine.

The NAC transcription factors play an important regulatory role in plant growth and development. In order to explore the impact of NAC6 on carotenoid metabolism in postharvest mango fruit, this study investigated changes in the carotenoid contents as well as the expression of NAC6 and key enzymes involved in carotenoid synthesis and metabolism in the mature peel and pulp of 2 mango varieties, “Tainong” and “Jinhuang”, at commercial maturity, during postharvest storage under constant temperature (20 ℃), constant humidity (85%), and dark conditions. The results showed that both mango varieties contained α-carotene, lutein, β-carotene, β-cryptoxanthin, and zeaxanthin. Throughout the storage process, the expression of NAC6 in both mango varieties showed a continuous upward trend, reaching a peak in the late stage of storage, followed by a slight decline. Correlation analysis showed that NAC6 might induce the gene expression of 1-deoxy-D-xylulose-5-phosphate reductoisomerase, farnesyl pyrophosphate synthase, geranylgeranyl pyrophosphate synthase, phytoene synthase, phytoene desaturase, ζ-carotene desaturase, carotenoid isomerase, β-carotene hydroxylase, and violaxanthin de-epoxidase in mango fruit, while inhibiting the gene expression of lycopene β-cyclase, neoxanthin synthase, and 9-cis-epoxycarotenoid dioxygenase. The expression of NAC6 in the peel and pulp of “Tainong” mango was significantly negatively correlated with the gene expression of carotenoid cleavage dioxygenase (CCD), with correlation coefficients of −0.841 0 and −0.838 3, respectively. NAC6 might delay the degradation of carotenoids by inhibiting the expression of CCD. The results from this research provide an experimental basis for the postharvest storage and preservation of mango fruit as well as its quality control.

In order to investigate the effect of mixed-mold fermentation on the bacterial community structure and quality of fish sauce made from mandarin fish viscera, changes in the bacterial community structure of mandarin fish viscera inoculated with a mixture of Aspergillus oryzae and Monascus (fish sauce A) or Aspergillus niger (fish sauce B) at a ratio of 3:1 during the fermentation process were analyzed using high-throughput sequencing. Additionally, changes in various quality parameters including pH, total acid content, amino nitrogen content, total soluble nitrogen content, total volatile basic nitrogen (TVB-N) content, volatile component contents, and free amino acid contents were evaluated. The results showed that mixed-mold fermentation significantly influenced the bacterial community. The diversity of bacterial community decreased during the fermentation process. Staphylococcus was found to be the dominant genus. The pH of fish sauce A and B decreased significantly, and consequently the content of total acids increased significantly throughout the fermentation. At the end of fermentation, the contents of amino nitrogen were 1.23 and 1.02 g/100 mL in fish sauce A and B, respectively, and the contents of total soluble nitrogen were 1.62 and 1.53 g/100 mL, respectively, both of which meet the standard for first-grade fish sauce. The TVB-N contents of fish sauce A and B were 152.81 and 154.12 mg/100 mL, respectively, complying with the national limit requirements. Gas chromatography-mass spectrometry (GC-MS) analysis identified 48 and 54 volatile components in fish sauce A and B, respectively, with the major one being 2,5-dimethylpyrazine at concentrations of 192.79 and 169.04 µg/mL, respectively. The contents of umami taste amino acids and sweet amino acids were significantly higher in fish sauce A and B than in unfermented fish sauce (P < 0.05). The correlation analysis results indicated that Staphylococcus made the greatest contribution to the quality of fish sauce and played a significant role in the formation of key characteristic flavor compounds in the late stage of fermentation. Overall, mixed-mold fermentation could effectively improve the quality of fish sauce. Fish sauce A had higher contents of amino nitrogen and total soluble nitrogen compared with fish sauce B, and consequently better overall quality.

This study aimed to analyze the effect of Issatchenkia orientalis on the microbial community structure and volatile flavor substance synthesis in Nongxiangxing Baijiu Jiupei in order to explore its effect on the microbial interaction and metabolism in the Jiupei. Under laboratory conditions, the microbial system for Nongxiangxing Baijiu brewing consisting of the Jiupei and Huangshui, a by-product of Baijiu brewing, was fermented directly (control group) or after inoculation with a strain of I. orientalis isolated from the Jiupei (experimental group). The composition of microbial communities, microbial interactions, and volatile flavor substances in the 2 groups were analyzed. The results showed that the microbial abundance of Jiupei changed after inoculation with I. orientalis; the relative abundance of Lactobacillus and Issatchenkia increased, and the relative abundance of Paenibacillus and Aspergillus decreased. Moreover, the microbial interaction was strengthened, making the microbial network structure more complex and compact. Compared with the control group, the volatile flavor substances in the experimental group increased significantly, 20 significantly differential volatile flavor substances were identified, and the contents of isopropanol, isoamylol and isobutanol increased significantly. The results of this study disclose the influences of inoculating I. orientalis on the microbial community structure and volatile flavor substances in Nongxiangxing Baijiu Jiupei and help to understand the impact of functional microorganisms on the microbial perturbation and metabolite synthesis in Jiupei.

Purpose: To explore the effects of kiwifruit peel polyphenols (KPP) on the antioxidant capacity of lipopolysaccharide (LPS)-stressed Caco-2 cells. Methods: The viability of Caco-2 cells in different treatment groups was determined by the cell counting kit-8 (CCK-8) assay, reactive oxygen species (ROS) and mitochondrial membrane potential by fluorescence spectrophotometry, the activity of superoxide dismutase (SOD), and the contents of glutathione (GSH) and malonaldehyde (MDA) by spectrophotometry, the gene expression of nuclear factor erythroid 2-related factor 2 (Nrf2), Kelch-like ECH-associated protein 1 (Keap1), NAD(P)H:quinone oxidoreductase 1 (NQO1), superoxide dismutase 1 (SOD1) and SOD2 by real-time quantitative polymerase chain reaction, and the protein expression levels of Nrf2, Keap1, and NQO1 by Western blot. Results: Compared with the LPS group, cell viability was elevated after 50 µg/mL KPP intervention (P < 0.05); the levels of ROS and MDA were decreased to 1.82 ± 0.28 and 5.08 nmol/mg (P < 0.05), respectively; mitochondrial membrane potential, SOD activity and GSH content were increased to 1.84 ± 0.10, 52.57 U/mg and 69.46 µmol/g (P < 0.05), respectively. Meanwhile, KPP intervention increased the gene and protein expression of Nrf2 and NQO1 (P < 0.05) and decreased Keap1 gene and protein expression (P < 0.05). Conclusion: KPP can enhance the antioxidant capacity of Caco-2 cells through the Keap1/Nrf2/NQO1 signaling pathway, thereby alleviating the cellular damage caused by LPS stress.

Objective: To study the hypoglycemic effect and mechanism of guar gum manno-oligosaccharides (GMOS) on streptozotocin-induced diabetic mice. Methods: GMOS was administered to diabetic mice for 6 weeks, and the changes in body mass and insulin resistance were monitored. Furthermore, indicators of glucose and lipid metabolism such as glucose (GLU), insulin (INS), high density lipoprotein cholesterol (HDL-C), and low density lipoprotein cholesterol (LDL-C) were determined. Hepatic histopathological changes were observed, and the expression of proteins involved in the adenosine monophosphate-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) signaling pathway and the activity of antioxidant enzymes in the liver were detected. Results: GMOS effectively relieved the body mass loss of diabetic mice, significantly alleviated glucose tolerance (30.3%) and enhanced insulin sensitivity (34.6%). Compared with the model group, GMOS decreased the levels of GLU, glycosylated serum protein (GSP) and LDL-C by 38.6%, 29.5%, and 27.3%, respectively, and increased the levels of insulin and HDL-C significantly. Moreover, GMOS reduced oxidative damage, activated the AMPK/PGC-1α signaling pathway, and improved the activities of superoxide dismutase (SOD) and catalase (CAT) in the liver. Conclusion: GMOS could reduce blood glucose and mitigate glucose and lipid metabolism disorder and oxidative stress caused by diabetes mellitus, indicating its potential as a functional food ingredient against diabetes.

A comprehensive and intuitive evaluation system for the quality of crabapples (Malus spp.) was established. In this study, 14 varieties of crabapples were tested. The core quality indexes were selected through variability analysis, correlation analysis, and principal component analysis (PCA) to establish the comprehensive quality evaluation model. The reliability of the model was verified by sensory evaluation and cluster analysis. In addition, the characteristics and utilization values of these varieties were investigated by cluster analysis. The results showed that there were significant differences in 18 quality indexes among the varieties and significant correlations among these quality indexes. PCA showed that the cumulative contribution rate of the first 5 principal components was 89.253%. Combining this result with those of correlation analysis, we found that single fruit mass, solid/acid ratio, sugar/acid ratio, and total flavanol content were the major quality indexes of crabapples. According to the comprehensive evaluation model, ‘123 Xiaopingguo’, ‘Longfeng’, ‘Cuifeng’ and ‘Huangtaiping’ had better fruit quality than the other varieties. The antioxidant activity of crabapple polyphenols showed a positive linear correlation with the contents of polyphenols and flavonoids with correlation coefficients of R2 = 0.837 and 0.728 for 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical scavenging capacity, R2 = 0.829 and 0.768 for 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH) radical scavenging capacity, and R2 = 0.575 and 0.969 for ferric ion reducing antioxidant power (FRAP), respectively. Likewise, the sensory evaluation scores were linearly correlated with the PCA scores (R2 = 0.862), indicating the reliability of the comprehensive evaluation model. The results of cluster analysis showed that the crabapple varieties could be divided into 4 categories. Category I included M. orbusta and ‘Haihong’, which could be processed into health products with high VC content. Category II included ‘Jixinguo’, ‘Longfeng’, ‘Cuifeng’ and ‘123 Xiaopingguo’, with good taste and being suitable for fresh consumption. Category III included ‘Adam’, ‘Profusion’, M. micromalus, ‘Brandywine’, and ‘Red Splender’, which are suitable for making polyphenols-rich health foods. Category IV included ‘K9 Qingshaguo’, ‘Kelsey’ and ‘Huangtaiping’, which can be processed into preserved fruit, juice, wine and other products. The results were consistent with those of PCA, corroborating the reliability of the model. The comprehensive quality evaluation system can provide a theoretical basis for the development and utilization of different varieties of crabapples and also provide a good scheme for the quality evaluation of crabapples.

Taste is an important quality attribute of tea. In order to find out the taste quality of green teas made from the major varieties in Wanzhou district, Chongqing, the taste profile of the tea infusions was determined by sensory evaluation and 5 taste components including catechins, free amino acids, alkaloids, flavanols and their glycosides, and organic acids were analyzed by targeted detection methods. The results showed that there were obvious differences in the taste quality of green teas prepared from the 4 varieties of tea trees. Sichuan middle- and small-leafed tea group variety had a strong taste, and ‘Anji Baicha’ had an obvious fresh and brisk taste with mellow sweet aftertaste. ‘Fuding Dabaicha’ tasted strong with fresh and brisk taste and mellow sweet aftertaste. ‘Zhonghuang 1’ tasted fresh and brisk but less strong. The results of taste component analysis showed that the Sichuan middle- and small-leafed tea group variety contained high contents of catechins but low contents of free amino acids. ‘Anji Baicha’ had the highest content of free amino acids. The content of each flavor component was high in ‘Fuding Dabaicha’, and the contents of total flavor components and water extract of ‘Zhonghuang 1’ were low. The results of principal component analysis (PCA) showed that the 4 varieties could be well distinguished. Thirteen major taste contributors such as rutin and caffeine were identified. The differential analysis indicated that aspartic acid, glutamic acid and theanine were the major contributors to the fresh and brisk taste characteristics of ‘Anji Baicha’ and ‘Fuding Dabaicha’. Yangmeiin-3-O-galactoside and chrysin were the major taste contributors for ‘Zhonghuang 1’ that distinguished it from the other 3 varieties. There were also large differences in taste components within the Sichuan middle- and small-leafed tea group variety, with samples C4 and C5 being closer to each other. They both contained high contents of flavonoid glycosides, having a strong astringent taste. This study provides a reference for research to improve the flavor quality of green tea in Wanzhou district.

In this study, gas chromatography-mass spectrometry (GC-MS) was used to analyze the chemical components of the essential oil extracted from the fruits of Aipinia oxyhylla Miq. (AOEO) by steam distillation. To evaluate the antimicrobial activity of AOEO against Listeria monocytogenes, the inhibitory zone diameter, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by means of filter paper and micro-double dilution methods. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed to observe the effect of AOEO on bacterial morphology. The antibacterial mechanism was investigated by measuring the growth curve, the change of electrical conductivity, the leakage of intracellular macromolecules, the activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA). The results showed that a total of 45 chemical components were identified in AOEO, mainly including terpenes, aromatic hydrocarbons and oxygen-containing derivatives. Among them, valencene, nootkatone, 2,6,10,10-tetramethylbicyclo[7.2.0]undeca-1,6-diene, (2S,4aR,8aR)-4a,8-dimethyl-2-(prop-1-en-2-yl)-1,2,3,4,4a,5,6,8a-octahydronaphthalene, (2R,8R,8aS)-8,8a-dimethyl-2-(prop-1-en-2-yl)-1,2,3,7,8,8a-hexahydronaphthalene and p-cymene were predominant. AOEO significantly inhibited the growth of L. monocytogenes with an inhibitory zone diameter of 14.20 mm. The MIC and MBC were 0.195 and 0.781 mg/mL, respectively. The growth curve showed that the antimicrobial activity of AOEO was concentration-dependent. SEM and TEM showed that AOEO destroyed the morphological structure of L. monocytogenes and changed the permeability of the cell membrane, thereby causing the leakage of a large number of electrolytes and macromolecular contents (nucleic acids and proteins) out of the cells. The dynamic balance of the SOD system was also destroyed by the oil while inducing the generation of a large number of free radicals, thus resulting in increased levels of lipid oxidation and MDA content in the cells. Therefore, AOEO inhibited the growth of L. monocytogenes and causes cell apoptosis by causing a series of cellular changes. This could be due to the synergistic action of multiple components and multiple targets of AOEO. Terpenes, aromatic hydrocarbons and ketones were tentatively identified as the major antibacterial substances of AOEO. This study provides a scientific theoretical basis for the development and utilization of Aipinia oxyhylla Miq. as a natural bacteriostatic agent in the food industry.

A total of 951 metabolites including 489 primary ones and 315 secondary ones were detected in plum fruit from 5 different varieties/lines in Guangdong by non-targeted metabolomics. For all plum varieties/lines, lipids were the most abundant primary metabolites, followed by sugars, alcohols, amino acids and organic acids, while the contents of nucleotides and vitamins were relatively low. Polyphenols were the most abundant secondary metabolites, followed by plant hormones, alkaloids and terpenoids, while the contents of phenylpropanoids and lignan were very low. The most abundant lipid component in Dami plum was undecanoic acid, accounting for 92.9% of the total lipids. The content of sugar in the fruit of plum is second only to lipid. The most abundant sugar in Dami plum was turanose, 9.5, 8 and 14.6 times as abundant as sucrose, glucose and fructose, respectively, which might be the major contributor to the honey flavor in Dami plum. A total of 170 amino acids and their derivatives were identified, greater than that of any other primary metabolites. L-malic acid was the major organic acid, accounting for 57.1% of the total organic acids and their derivatives. VB6 was the most abundant vitamin, accounting for 51.5% of the total vitamins. Flavonoids were the most abundant polyphenols, accounting for 77.7% of the total polyphenols. Altogether, 84, 73, 113 and 34 differential metabolites were identified between Dami plum and Qingpi, Xiaomi, Hongxian and Daguochishu Sanhua plum, respectively. Metabolic pathway enrichment analysis of differential metabolites showed that the differential metabolites of the 4 groups were mainly enriched in amino acids, flavonoids, anthocyanins, alkaloids and synthetic and metabolic pathways. The major differential metabolites between Daguochishu Sanhua and Dami plum were flavonoids and phenols such as C-pentosyl-luteolin-C-hexoside, dopamine and trilobatin, and nucleotides such as nicotinamide adenine dinucleotide and β-nicotinamide mononucleotide. These substances may be the key differential metabolites between the 2 varieties at the mature stage.

In this research, the differences in protein and fatty acid composition among camel, cow and goat milks were analyzed by gel electrophoresis (GE) and gas chromatography (GC). The GE results showed that there were differences in the proportion of proteins in camel milk from different regions, and the production process had a significant effect on both camel milk protein and milk fat globule membrane protein composition. There were significant differences in protein composition among camel, cow and goat milks, and camel milk did not contain β-lacglobulin or αs1-casein, while cow and goat milks did not contain immunoglobulin G2 (IgG2) or IgG3. Therefore, GE could be used for the identification of camel milk mixed with cow or goat milk. The GC results showed that 31 fatty acids were detected in both camel and goat milks, and 29 fatty acids in cow milk. Camel milk contained fewer short-chain fatty acids than cow and goat milks, while the contents of most long-chain fatty acids were significantly higher than those in cow and goat milks. Principal component analysis (PCA) of the fatty acid composition data showed a clear separation of milks from different species and a clear discrimination between pure and adulterated camel milk. PCA can be used for the identification and analysis of fatty acids in camel milk mixed with cow milk and goat milk.

This study aimed to explore the effect of ultrasound-assisted pH shift on the structural and functional properties of soybean lipophilic proteins (SLP). SLP were modified under ultrasound (240 W, 20 min) and extreme pH (pH 1 or 12) conditions. The primary, secondary and tertiary structures of native and modified SLP were characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), free sulfhydryl content, Fourier transform infrared (FTIR) spectroscopy, and fluorescence spectroscopy, and their functional properties were analyzed. The results showed that ultrasound-assisted alkaline pH shift resulted in the greatest changes in the structural and functional properties of SLP. The average particle size of SLP decreased from 5 245.33 to 447.13 nm, the ζ-potential value decreased from − 5.95 to − 18.53 mV, the free sulfhydryl content decreased, the α-helix content increased, and the fluorescence spectrum exhibited a blue shift and a decrease in fluorescence intensity. In addition, the solubility increased from 9.84% to 92.04%, and the emulsifying and foaming properties increased. Therefore, ultrasound and pH shift treatments have a synergistic effect on the structural and functional properties of SLP, and they are closely correlated with each other.

In order to investigate the effect of ultrasound on the structure and physical stability of chicken myofibrillar protein (MP) under low-salt conditions (0.15 mol/L NaCl), as well as the oxidizing effect of free radicals generated by ultrasound on MP, this study investigated the changes in the structure and oxidative properties of MP under low-salt conditions after ultrasound treatments (20 kHz, 450 W for 0, 3, 6, 9, and 12 min). The results showed that compared with the control group, the solubility, physical stability, and absolute ζ-potential of MP under low-salt conditions increased significantly (P < 0.05) with ultrasonic treatment time, whereas the turbidity and particle size decreased significantly (P < 0.05). The solubility was increased to 58.5% after 12 min of ultrasonic treatment. After ultrasonic treatment, the surface hydrophobicity and molecular flexibility were significantly increased, indicating that ultrasonic treatment caused the highly aggregated structure of myofibrillar protein to unfold and the internal hydrophobic groups to be exposed under low-salt conditions. After ultrasonic treatment for more than 6 min, the free sulfhydryl content of MP began to gradually decrease, whereas the content of disulfide bonds increased. After ultrasonic treatment for 12 min, the contents of free radicals, carbonyl groups and dimerized tyrosine (by 20.55%) were significantly increased (P < 0.05), while the free amino group content was decreased significantly (P < 0.05). In conclusion, ultrasonic treatment changed the structural properties of MP under low-salt conditions and increased its physical stability, thereby contributing to the formation of emulsions. Ultrasonic treatment can generate free radicals; ultrasonic treatment time for 6 min can exacerbate the oxidation of MP. So, attention should be paid to the oxidizing effect of free radicals generated by ultrasound on MP when applying ultrasonic treatment to improve the functional properties of MP.

The objective of this study is to investigate the mechanism of the modification of pea protein isolate (PPI) by transglutaminase (TG) in combination with dynamic high-pressure microfluidization (DHPM) and to clarify the applicability of the modified PPI in Pickering emulsion. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy showed that the morphology of PPI particles became more uniform after the modification. The degree of cross-linking with TG increased, and the tertiary structure of protein molecules changed. In addition, the surface hydrophobicity and endogenous fluorescence of PPI decreased, the emulsifying properties improved and the average particle size decreased. The Pickering emulsion stabilized by the modified PPI had improved stability and emulsifying capacity, and the best emulsion stability was observed at 120 MPa. TG-DHPM modification could provide a feasible method for the application of PPI in Pickering emulsion. This study provides an experimental basis for the development of high-performance Pickering emulsion systems and is of significant reference value for the functional modification of natural proteins.

Ion chromatography was used to investigate the effects of γ-ray irradiation dose, vitamin C (VC) content and niacinamide content on nitrite degradation in aqueous solution and spiced donkey meat, and the volatile components of irradiated spiced donkey meat were analyzed by gas chromatography-ion mobility spectrometry. The results showed that γ-ray irradiation could effectively degrade nitrite in both aqueous solution and spiced donkey meat. A synergistic effect was observed when γ-ray irradiation and VC were used together. Nicotinamide had an inhibitory effect on the irradiation degradation of nitrite in aqueous solution, but had a synergistic effect on the irradiation degradation of nitrite in spiced donkey meat. Nitrite ions in aqueous solution were converted to nitrate ions by the irradiation. After 8 or 10 kGy irradiation, the contents of hexanal and heptanal increased, and donkey meat had an off-flavor. This study provides technical support and a theoretical basis for the degradation of nitrite in spiced donkey meat by γ-ray irradiation.

In this study, the effect of a mixed coating of the cereal cell wall polysaccharides arabinoxylan (AX), (1,3;1,4)-β-D-glucan (BG) and α-cellulose on the reactive oxygen species (ROS) metabolism system of postharvest apricot fruits and its action mechanism were investigated. The results showed that the coating could effectively inhibit the increase of malondialdehyde (MDA) and ROS contents. The contents of MDA, H2O2, and O2– in the control group were 37.50%, 33.33%, and 57.14% higher than those in the ABF-C8 treatment group (8 g/100 mL α-cellulose), respectively. In addition, the coating treatment maintained the antioxidant capacity and antioxidant enzyme activity of apricot fruits, and its ascorbic acid and total phenol contents were 73.33% and 8.40% higher than those in the control group, respectively. The polysaccharide coating could effectively retard the generation and accumulation of ROS during apricot fruit respiration, thereby preserving the integrity of the cell membrane. At the same time, the coating was able to form a barrier against gas and water between the fruit and the external environment, maintaining the activity of ROS scavenging enzymes as well as the antioxidant capacity, thus prolonging the storage period of apricot fruits after harvest.

Mustard essential oil (MEO) nanoemulsions fortified with citrus pectin and tween-80 (MEO-NE-PT) or tween-80 (MEO-NE-T) were prepared by high-pressure homogenization followed by ultrasonication, and comparative analysis was performed on the microstructure, storage stability, pH, ionic strength and thermal tolerance between MEO-NE-PT and MEO-NE-T. The application of MEO-NE-PT to the postharvest preservation of ‘Shatangju’ mandarin was evaluated. It was found that MEO-NE-PT exhibited superior stability with smaller fluctuations in particle size and polydispersity index (PDI). The minimum inhibitory concentration (MIC) of MEO-NE-PT was 64 μL/L, much lower than those of MEO (256 μL/L) and MEO-NE-T (128 μL/L). Furthermore, after MEO-NE-PT treatment at 64 μL/L for 6 h, the germination rate of Geotrichum candidum spores was only 6.67%, and the length of the germ tube was only 8.57 μm, both significantly lower than 100% and 165.02 μm for the control group (MEO), respectively. The results of scanning electron microscopy (SEM) revealed that treatment with MEO-NE-PT caused the mycelium of Geotrichum candidum to wrinkle and break apart. Compared with the control group, MEO-NE-PT treatment could significantly reduce the decay rate and quality loss of ‘Shatangju’ mandarin, while delaying the decline in hardness and total soluble solids. As a safe and effective antimicrobial agent, MEO-NE-PT could control the growth of Geotrichum candidum and maintain the post-harvest quality of ‘Shatangju’ mandarin.

To investigate the regulatory effect and possible mechanism of exogenous sodium nitroprusside (SNP) treatment on the pericarp browning of refrigerated ‘Nanguo’ pear fruit, the effect of 1.0 mmol/L SNP pretreatment on the pericarp browning of ‘Nanguo’ pear fruit during shelf life at room temperature after 180 days of refrigerated storage was investigated. The results showed that browning symptoms appeared in the SNP-treated fruit three days later than the control fruit, and at the end of the shelf life, the browning incidence and browning index were 41.8% and 31.9% of those of the control fruit, respectively. The treatment protected the structural integrity of pericarp cells and inhibited the elevation of membrane permeability. Further analysis revealed that at the end of the shelf life, the superoxide anion, hydroxyl and 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH) radical scavenging capacity of the SNP-treated fruit were 1.65, 1.13, and 1.24 times higher than those of the control fruit, respectively. Meanwhile, the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) was significantly reduced, which was 25.2% and 32.8% lower than that of the control group, respectively, and the activities and gene expression of polyphenol oxidase and peroxidase were 17.5%, 28.8%, 37.5% and 39.2% lower than those of the control group, respectively. In addition, the synthesis of phenolics was inhibited to some extent. In conclusion, SNP treatment could alleviate the occurrence of pericarp browning in refrigerated ‘Nanguo’ pear fruit by inhibiting membrane lipid peroxidation and maintaining cellular structural integrity and function.

In this study, the changes in the water content, acid value, peroxide value, and antioxidant activity of macadamia kernels were determined at different storage temperatures (4 ℃, normal temperature and 60 ℃) in 5 packaging systems, including conventional packaging, vacuum packaging, vacuum deoxidizer packaging, nitrogen packaging and nitrogen deoxidizer packaging, and a kinetic model to predict the shelf life of macadamia kernels was established based on the peroxide value. The results showed that nitrogen and nitrogen deoxidizer packaging significantly inhibited the increase of acid value and peroxide value, reduced oxidative rancidity, slowed down the decline of total phenol content, and maintain high 1,1-diphenyl-2-picrylhydrazyl, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) cationic radical and hydroxyl radical scavenging ability in macadamia kernels. Peroxide value was positively correlated with both storage temperature and time (P < 0.05), and its changes were fitted to a first-order kinetic model. The Arrhenius equation had good fitness, and the error of the prediction model was less than 14%. Nitrogen packaging had the longest shelf life, with measured values of 215, 180, and 108 days at 4 ℃, normal temperature, and 60 ℃, respectively, followed by nitrogen deoxidizer packaging, with measured values of 205, 175, and 104 days, respectively.

The study aimed to investigate the changes of metabolites and related flavors in the muscle of fresh mandarin fish (Siniperca chuatsi) during 24 h of postmortem refrigeration at 4 ℃ by ultra performance liquid chromatography coupled with high resolution mass spectrometry (UPLC-HR-MS). Non-targeted metabolomics was applied for multivariate statistical analysis, metabolic pathway analysis and related flavor calculation of the differential metabolites after 0 versus 2, 4, 6, 9, 12 and 24 h. The results showed that 33 differential metabolites were identified, including 3 organic acids and derivatives (amino acids and organic acids); 8 organic heterocyclic compounds (purines, purine derivatives and lactones); 7 nucleosides, nucleotides and analogues (purine nucleosides, purine nucleotides and pyrimidine nucleotides); 9 organic oxygen compounds (carbohydrates and their conjugates, as well as a small amount of alcohols); 4 lipid and lipid molecules (fatty alcohols and fatty acid esters); 1 flavonoid glycoside; and 1 alkaloid or its derivatives. Through metabolomic pathway analysis (MetPA) and Kyoto Encyclopedia of Genes and Genomes analysis, 9 key differential metabolites were identified including succinic acid, L-aspartic acid, 5’-adenosine monophosphate (AMP), inosine, adenyl succinic acid, xanthine, 5’-guanosine monophosphate (GMP), ribose 5-phosphate, and hypoxanthine. The major metabolic pathway involving these key differential metabolites was purine metabolism, followed by L-aspartic acid metabolism, glutamic acid metabolism and the tricarboxylic acid (TCA) cycle. By calculating the relative taste activity value (RTAV) and relative equivalent umami concentration (REUC), it was found that umami amino acids such as L-aspartic acid together with AMP and GMP mainly contributed to the taste of fresh mandarin fish, while the major taste compounds were AMP and GMP after 2–6 h of refrigeration and GMP after 9–24 h. Overall, the taste of fresh mandarin fish was best. During 24 h of storage at 4 ℃, the umami of mandarin fish decreased due to a decrease in L-aspartic acid content, but it increased between 9 and 24 h due to the accumulation of GMP.

Based on the click chemical reaction between hybrid rhodamine and thiol compounds and the declick chemical reaction caused by the coordinative interaction between thiol compounds and mercury ions, a ternary system of coumarin hybrid rhodamine probe, 1,3,5-benzenetrithiol and Hg2+ for fluorescence detection of Hg2+ was constructed. In this system, the probe underwent an addition reaction with the thiol group in 1,3,5-benzenetrithiol, destroying the conjugate structure of the probe and thus resulting in quenching of its red fluorescence. Hg2+ could remove 1,3,5-benzenetrithiol from the probe’s structure by coordinative binding to the compound, so the conjugate structure and red fluorescence of the probe were restored. The fluorescence intensity of the probe had a good linear relationship with the concentration of Hg2+ in the range of 5 × 10-9-1 × 10-8 and 1 × 10-8–1.1 × 10-7 mol/L, and the detection limit was 2 × 10-9 mol/L. Common heavy metal ions had no significant interference on the specific recognition of Hg2+. The recoveries of Hg2+ from spiked drinking water samples ranged from 86.7% to 110.2%.

In this study, an analytical method based on gas chromatography-mass spectrometry (GC-MS) was developed for the simultaneous determination of 8 common psychoactive substances derived from cathinone compounds in tea. Extraction, clean-up and chromatographic and mass spectrometric conditions were optimized. As a result, an alkaline solution containing methanol was selected as the extraction solvent, and the extract was cleaned up on an HLB solid-phase extraction (SPE) cartridge filled with N-propylethylenediamine (PSA) and separated on a DB-17MS capillary column (30 m × 0.25 mm, 0.25 μm). The mass spectrometer was operated using an electrospray ionization (EI) source in the selected ion monitoring (SIM) mode. The calibration curves showed good linearity for the 8 analytes in the concentration range of 0–200 μg/L, with correlation coefficients (r2) higher than 0.998. The limits of detection (LOD, RSN = 3) and limits of quantification (LOQ, RSN = 10) were 7 and 25 μg/kg, respectively. The recoveries from negative samples spiked at 1 ×, 2 × and 10 × LOQ were in the range of 67.2%–117.6%, with relative standard deviations (RSD) of 4.3%–12.3% (n = 6). In summary, this method has good stability and high sensitivity, and is suitable for simultaneous determination of the psychoactive substances derived from cathinones in tea.

An analytical method based on quick, easy, cheap, effective, rugged and safe (QuEChERS) cleanup using an enhanced matrix removal lipid (EMR-Lipid) sorbent combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established for the rapid determination of 57 industrial dyes illegally added in foods. The sample was extracted with acetonitrile, and the extract was purified by QuEChERS. The analytes were separated on an Agilent ZORBAX Eclipse RRHD C18 column (3.0 mm × 150 mm, 1.8 μm) with gradient elution using a mobile phase composed of acetonitrile and 0.1% formic acid, detected using an electrospray ionization source operated under the positive mode with multiple reaction monitoring (MRM), and quantified by an external standard method. The results showed that good linearity was observed for all analytes in the concentration range from 20 to 300 ng/mL with correlation coefficients higher than 0.999. The limits of detection (LOD) and quantitation (LOQ) were 10 and 25 μg/kg, respectively. The recoveries at 3 spiked levels (25, 100 and 250 μg/kg) were 72.1%–119.1%, with relative standard deviations (RSDs, n = 6) of 0.19%–4.58%. The developed method was used to detect illegal addition of industrial dyes in soybean products, condiments, aquatic products, and meat products (n = 20 for each type). Alkaline yellow was detected in one bath of Sichuan pepper powder at a level of 32.9 μg/kg. In conclusion, this method is rapid, accurate, sensitive, and suitable for the determination of the 57 industrial dyes illegally added in foods.

Postmortem muscle is highly susceptible to oxidative conditions, thus leading to deterioration of meat quality in terms of tenderness, color, and water-holding capacity (WHC). Therefore, the regulation of the oxidation mechanism is a major concern in research on postmortem meat quality. Reactive nitrogen species (RNS) are free radicals and nitro compounds with high oxidation activity derived from the interaction between nitric oxide (NO) and compounds including reactive oxygen species (ROS). RNS not only regulates mitochondria to promote cellular metabolic function, but also mediates mitochondrial damage to induce cell apoptosis, thereby regulating the quality of postmortem meat. Relevant research results need to be summarized urgently. Therefore, this paper provides an overview of the production and metabolism of RNS in cells, elaborates on the mechanism by which RNS regulates normal physiological functions of cells through mitochondria, induces cell apoptosis through causing mitochondrial damage and mediates oxidation mechanism including lipid peroxidation and protein oxidation, and discusses the mechanism by which RNS affect the tenderness, color, and WHC of postmortem muscle. We anticipate that this review will provide a theoretical reference for improving postmortem ageing.

Ultrasonic-assisted thermal treatment, as a mild and effective emerging sterilization technology, has been successfully used to control the microbial safety of various foods. In particular, it has broad application prospects in the field of dairy processing. Ultrasonic provides a unique strategy to dynamically inactivate bacteria, which plays a significant positive role in alleviating the pressure on the dairy supply chain and reducing the economic loss caused by dairy spoilage. This article reviews the research progress that has been made in the past decade on the mechanism behind the ultrasonic-assisted thermal sterilization of Bacillus subtilis in terms of the cavitation effect of ultrasonic, damage to the cell wall and membrane, generation of free radicals and antibacterial substances, and damage to cell metabolism-related enzymes. A new sterilization method for controlling the number of bacteria contaminating dairy products is proposed in this paper, aiming to provide a reference for better research and application of this technology for controlling the contamination of heat-resistant Bacillus during the storage and processing of dairy products, reducing the risk of dairy quality deterioration caused by the residue of heat-resistant Bacillus, and ensuring the quality and safety of dairy products during its shelf life.

The postmortem conversion of muscle to meat goes through a series of complex physiological and biochemical changes, among which protein post-translational modifications (PTMs) are key factors affecting meat quality. Glycolysis is the major energy supply pathway in postmortem muscle. PTMs can change the function and structure of pyruvate kinase, a rate-limiting enzyme in the glycolytic pathway, which can in turn affect meat quality. Beginning with an overview of the structure and function of pyruvate kinase, this article reviews the recent research progress on the effects of PTMs of pyruvate kinase on its function and structure and the effects of pyruvate kinase phosphorylation, acetylation and S-nitrosylation on meat quality.

Ectomycorrhizal (ECM) fungi, which can form ectomycorrhiza with plants, are an important link between the above-ground symbiotic plants and the subsurface ecosystems, and many of them are nutritious and delicious food. ECM fungi promote the absorption of mineral nutrients by plants, especially for limiting mineral elements such as phosphorus, thereby improving the growth of plants. It is generally believed that ECM fungi acquire mineral nutrients from soil mainly through their weathering effect on soil minerals that are difficult to degrade, but the weathering process and mechanisms are still not clear. Through field investigation, strain isolation and weathering tests, it is found that many ECM fungi cannot weather minerals by up-regulating the synthesis of small molecular organic acids, showing a weak ability to weather mineral. Particularly, they cannot use phosphorus in apatite independently. Bio-omics studies find that in forest soils, some ECM fungi with weaker weathering ability can promote the dissolution of minerals by enrichment of mineral-weathering bacteria, and absorb dissolved mineral nutrients to supply host plants through their high-affinity ion transport systems. In addition, ECM fungi can enrich special versatile oxalate-degrading bacteria (such as those that have the capability of nitrogen fixation and promoting mycorrhizal formation) to eliminate the inhibitory effect of excess oxalate on mineral weathering and nutrient absorption. It has been confirmed that ECM fungi can regulate the rhizosphere microbial community structure and promote the mutually cooperative relationship among plants, fungi and bacteria to maintain a healthy and sustainable forest ecosystem. This paper reviews the symbiotic strategies of ECM fungi from the perspective of mineral weathering, puts forward new ideas for increasing the biomass of edible fungi in woodlands and promoting the sustainability of woodland ecosystems, and gives an outlook on future research directions in this field.

Solid-state fermentation in mud pits is a typical brewing process for nongxiangxing baijiu and fuyuxiangxing baijiu. Pit mud is the functional carrier of mud pits, in which the abundance, diversity, metabolic activity and interaction of microorganisms could directly affect the quality of baijiu. This paper reviews the application of traditional culture and non-culture techniques in research on microorganisms in pit mud, the spatiotemporal differences in microbial community structure, the functional microorganisms and their interactions, the development and improvement of the methods for the quality evaluation of pit mud, and pit mud maintenance and aging focusing on the functional strains, and summarizes the development history and application status of different techniques in the field of research on microorganisms related to the production of Chinese baijiu, the growth and decline patterns of prokaryotic and eukaryotic microorganisms during pit mud aging, the spatial difference in the distribution of prokaryotic and eukaryotic microorganisms in the pit, and the functions and interdependence of the core functional microorganisms in pit mud such as caproic acid bacteria, butyric acid bacteria, lactic acid bacteria, acetic acid bacteria and methane bacteria, the reason for pit mud aging, the transformation of the criteria for quality evaluation pit mud from traditional sensory and physicochemical analysis to the comprehensive evaluation system, and studies on pit mud maintenance and aging based on the functional properties of core strains. The purpose of this review is to provide a reference for evaluating the microbial diversity, exploring the metabolic function of microbial community and improving the quality of pit mud.

Flavor substances endow foods with unique characteristics, which determine the aroma and taste sensory attributes of foods, directly affect food quality and reflect the characteristic quality and quality requirements of foods. Flavor substances play an important role in the research, production and consumption of foods, and deep research, development and utilization of flavor substances are important for the development of the food industry. In this paper, the definition and classification of flavor substances in foods are introduced, the synthesis mechanism of flavor substances through the fatty acid, amino acid, and carbohydrate metabolic pathways are elucidated, and the detection methods of flavor substances and their applications in the food processing industry are reviewed. Finally, the limitations of flavor substance detection are discussed and an outlook on future directions in this field is given. We hope that this review will provide directions for the development and utilization of food flavor substances.

Acylation is a common method for chemical modification of proteins, which can effectively improve the functional properties of proteins and has been widely used in food processing in recent years. The effect of acylation on protein modification is related to the degree of modification, and low degree of acylation modification can significantly improve the solubility, thermal stability, foaming and emulsifying properties, gelation properties, film-forming properties and nutritional quality of proteins. This paper reviews the effect of acylation modification on protein structure, physicochemical properties, and functional properties, as well as the application of acylated proteins in food and other fields. Hopefully, this review will provide a theoretical reference for protein modification research.

Large-ring cyclodextrin (LR-CD) is a cyclic α-1,4-glucan consisting of nine to several hundred glucopyranose units. LR-CD is mainly prepared by the cyclization activity of cyclodextrin glucosyltransferase or 4-α-glucanotransferase that catalyzes intramolecular transglycosylation reaction on amylose. Compared with common α-, β-, and γ-CD, LR-CD has a larger cavity size and exhibits unique structural and physicochemical properties, showing potential applications in several fields like food, medicine and biology. However, LR-CD has not been industrially produced or applied due to the high cost and low productivity as well as lack of effective separation and purification methods. In this article, recent progress and challenges on the enzymatic preparation of LR-CD are reviewed from the aspects of optimizing reaction substrates, designing new reaction pathways based on template induction, enzyme modification, and separation and purification of products. We hope this article could provide a reference for the industrial production and application of LR-CD.

Rice wine is made from rice fermented by Jiuqu. It is very popular among consumers because of its rich nutrient content and unique flavor. Microorganisms from Jiuqu or the environment play an important role in the formation of rice wine flavor. In this article, the diversity and dynamic changes of the microbial community in the brewing process of rice Jiuqu and rice wine are reviewed, the relationship between the microbial community and the formation of the flavor of rice wine is analyzed, and the current status of research on and the application value of functional microorganisms involved in the fermentation of rice wine are summarized. At last, the deficiencies of current studies on rice wine microorganisms and the metabolic mechanism of rice wine flavor are discussed, and an outlook on future research directions is given. This review will provide a theoretical reference for improving the quality of rice wine and promoting the standardized production of rice wine.