Abstract:The flavor profile of soybean-based foods was a complex system shaped by diverse volatile compounds generated during growth and processing. To date, more than 300 kinds of volatile flavor components have been identified in non-fermented products such as soybeans, soymilk, and soybean proteins. And more than 200 kinds of volatile flavor components have been identified in fermented soybean foods such as fermented black beans and soybean paste. These components include esters, aldehydes, alcohols, ketones, acids, furans, pyrazines, alkanes, sulfur compounds, and etc. Flavor formation in non-fermented soybean products primarily originated from the enzymatic oxidation of polyunsaturated fatty acids (e.g., linoleic and linolenic acids) naturally present in soybeans. This process was catalyzed by lipoxygenase and fatty acid hydroperoxide lyase during processing. The flavor of fermented soybean foods, on the other hand, originated from the complex enzyme systems released during the microbial fermentation process, which metabolized some of the inherent flavor substances in the raw materials. Meanwhile, proteins, fats, carbohydrates, and etc., were decomposed into complex flavor precursors such as peptides, amino acids, fatty acids, and sugars. Subsequently, during the post-fermentation period, a variety of flavors were formed through complex fermentation metabolism and biochemical reactions. Consequently, even within the same category of soybean foods, flavor profiles might exhibit significant variations due to differences in raw materials and processing conditions that regulated oxidation and other biochemical pathways. The characteristic flavors and formation mechanisms of three representative soybean foods:soymilk tofu, Yangjiang Douchi (fermented black beans), and plant-based fermented soybean milk were introduced. The formation mechanism of the flavor of soybean foods was complex. When developing soybean foods, specific and targeted research on the raw materials and processing objectives was required, and it was impossible to generalize.

Abstract:As an important direction for the application of synthetic biology technologies, the bio-synthesized food additives and ingredient industry is emerging prominently in the global food industry field by virtue of its technological advantages and has attracted widespread attention. Biosynthesized food additives and ingredients not only can provide functions and nutrients that traditional food additives and ingredients cannot achieve, but also contribute to addressing sustainability issues in the food supply chain. However, due to their novelty, the management and regulations related to biosynthesized food additives and ingredients are still in developmental stages worldwide, with varying strategies and regulatory systems among different countries and regions. The current status of regulations and management, regulatory systems, management institutions and risk assessment mechanisms and the composition of the standard systems of biosynthetic food additives and ingredients at home and abroad have been compared and analyzed. The study revealed that the management of biosynthetic food additives and ingredients in China was less perfect compared to that in foreign countries. The differences in the regulatory systems were mainly manifested in the aspects of regulation formulation, implementation and supervision. Meanwhile, the differences in management institutions and risk assessment mechanisms had an impact on the management efficiency and effectiveness of biosynthetic food additives and ingredients. The differences in the standard systems also directly affected the effectiveness and consistency of supervision. In addition, some countermeasures and suggestions were put forward aiming at these differences, with the intention of providing references and suggestions for the standardized management of biosynthetic food additives and ingredients in China.

Abstract:D-allulose is a novel low-calorie rare sugar with special physiological functions, including blood sugar regulation and antioxidant effects. In present, the biological synthesis of D-allulose mainly utilized D-allulose 3-epimerase to catalyze the conversion of D-fructose into D-allulose. The large-scale biosynthesis of D-allulose using biological enzymes has primarily focused on improving the catalytic activity, thermal stability, and acid tolerance of D-allulose 3-epimerase to meet industrial production requirements. The research progress on the current status of D-allulose production and the latest advances in its biosynthesis, including molecular-directed modification of isomerases, ultra-high-throughput screening assisted by directed evolution, and novel enzyme immobilization strategies to enhance the industrial properties of D-allulose 3-epimerase were summarized. Furthermore, the application of whole-cell catalytic systems in D-allulose production was also discussed. The aim of this review was to provide a reference for the efficient and green biosynthesis of D-allulose and to propose challenges and possible solutions in industrial production.

Abstract:Sorghum 3-deoxyanthocyanins (3-DAS) can inhibit the activities of α-amylase and α-glucosidase, but the mechanism is still unclear. The differences in the enzyme inhibitory activities of 3-DAS among different sorghum varieties were investigated to determine the sorghum 3-DAS extract with the strongest inhibitory effect on α-amylase and α-glucosidase. A variety of spectroscopic techniques and enzyme kinetic analysis were used to further explore the interaction mechanism between 3-DAS and the two glycoside hydrolases. The results showed that 3-DAS from Hong Mao Grain No.6 extract had the highest content and the strongest enzyme inhibitory activity, but its action characteristics for α-amylase and α-glucosidase were slightly different. 3-DAS inhibited α-amylase in a non-competitive manner, but inhibited α-glucosidase in a competitive mixed manner. The binding of sorghum 3-DAS to the enzyme resulted in a red shift of the characteristic absorption peaks of the protein cytoskeleton around 200nm for α-amylase and α-glucosidase, a static quenching and a static-dynamic mixed quenching of the intrinsic fluorescence of the two enzymes, respectively, and an increase in the hydrophobicity of the environment around the tryptophan and tyrosine residues of the enzymes. Sorghum 3-DAS could reduce the content of α-helix structure of α-amylase and α-glucosidase, thereby changing the conformation of the enzyme. The interaction between sorghum 3-DAS and the two glycoside hydrolases was dominated by electrostatic force, and the binding process was a spontaneous exothermic reaction. The results showed that sorghum 3-DAS had potential value as an inhibitor of α-amylase and α-glucosidase, and the results aimed to provide basic data support for high-value application of sorghum and its by-products.

Abstract:D-allulose, a promising low-calorie natural sweetener and a key member of the rare sugar family, exhibits physiological benefits in mitigating multiple diseases. As the C-3 epimer of D-fructose, D-allulose was synthesized through the catalytic action of D-allulose 3-epimerase (DAE). However, industrial-scale sugar epimerization required high-temperature conditions (greater than 65℃), and existed DAEs could not meet this requirement. To address this bottleneck, a hyperthermophilic DAE (TI-DAE) was immobilized using diatomite as a solid core, polyethyleneimine (PEI) as a protective shell, and glutaraldehyde (GA) as a cross-linking agent, resulting in the formation of a core-shell-structured immobilized enzyme (TI-DAE@Diatomite-PEI-GA), and its structure and performance were characterized. The result revealed that immobilized enzyme TI-DAE@Diatomite-PEI-GA exhibited better pH and thermal stability than the free enzyme TI-DAE. The half-life of TI-DAE@Diatomite-PEI-GA was greater than 24h, 11 times higher than free enzyme under 90℃. Furthermore, TI-DAE@Diatomite-PEI-GA retained over 70% relative activity after 20 batches of converting 500g/L D-fructose into D-allulose. The results proved that the enzyme immobilization technology based on diatomite covalent cross-linking could greatly improve the thermostability of DAE, reduce the cost of industrial production of D-allulose, break through a technical bottleneck of current industrial production, and lay a foundation for promoting the industrialization of enzymatic synthesis of D-allulose.

Abstract:Low molecular weight oyster peptides(LOPs)have various biological activities, but it has the defects of fishy odor and easy degradation by gastrointestinal digestive juices. It has found that the undesirable flavor of LOPs can be improved significantly by encapsulating with double emulsion, but the digestive and absorptive properties of LOPs encapsulated with double emulsion have not been sufficiently studied. Taking LOPs as the research object, interface properties were analyzed, W₁/O/W2 double emulsion was used to encapsulate LOPs, and the digestion and absorption characteristics of LOPs were studied by using in vitro simulated digestion and single-layer Caco-2 cell model. The results showed that LOPs had good hydrophilicity but couldn't reduce the interfacial tension between oil and water. During the simulated digestion process in vitro, the average particle size of LOPs double emulsion increased from initial (725.5±25.4) nm to (944.6±21.8)nm and finally decreased to (772.8±21.4)nm. The encapsulation rate decreased from 88.35% to 30.01%. Optical microscopic images showed that it had aggregation with different degrees at the stage of gastric digestion and ruptured at the stage of intestinal digestion. The results of single-layer Caco-2 cell model of in vitro simulated absorption experiments showed that the transport mode of LOPs was passive diffusion, while the transport mechanism of LOPs double emulsion was outflow effect. Double emulsion of LOPs could effectively improve the bioavailability of LOPs and provide good protection and slow-release effects on LOPs.

Abstract:Aging is an inevitable biological phenomenon that encompasses numerous physiological changes. Oxidative stress is one of the main reasons for exacerbating the symptoms of aging, and resistance to oxidative stress is an effective means of reducing the symptoms of aging. The unsaponifiable matter (USM) in walnut oil is a kind of highly active ingredient, which has important development and application value. The effect of USM from walnut oil on HepG2 cells was investigated using an in vitro D-galactose-induced senescence model of HepG2 cell and cell viability, cellular oxidative stress levels, intracellular inflammatory factor content, and intracellular liver function levels were used as evaluation indexes. The impact of USM on D-galactose-induced damage in HepG2 cells was examined using Western Blot analysis. The findings indicated that pre-treatment with USM at concentrations of 50,75, 100μg/mL effectively mitigated the reduced viability of D-galactose-damaged HepG2 cells, while also enhanced the enzymatic activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT). The concentrations of lipid oxidation products, including malondialdehyde (MDA), inflammatory cytokines (TNF-α, IL-1β, IL-6), alanine and aspartate aminotransferase (ALT, AST), and alkaline phosphatase (AKP), exhibited a decrease. Furthermore, USM were found to enhance the translocation of nuclear factor E2-related factor 2 (Nrf2) into the cytoplasm and nucleus, leading to the activation of downstream target proteins such as heme oxygenase-1 (HO-1) and quinone NADH dehydrogenase 1 (NQO1). The USM of walnut oil have been shown to inhibit the senescence induced by D-galactose in HepG2 cells through activation of the Nrf2/Keap1 signaling pathway. The results aimed to provide theoretical references for the development of functional products from walnut oil.

Abstract:To evaluate the anti-inflammatory and sleep-improving properties of Actinidia kolomikta fruit flavonoid extract (AFFE), macrophage RAW264.7 inflammatory model, mouse hippocampal neuronal cells HT22, and Drosophila melanogaster were used as experimental subjects and the effects of AFFE on inflammatory mediators, neurotransmitters, and sleep duration were analyzed. The results showed that in lipopolysaccharide-induced RAW264.7 cells, 250μg/mL AFFE reduced the production of NO, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) by 62.71%, 47.38%, and 65.53%, respectively. Additionally, the mRNA expressions of TNF-α and IL-6 were significantly down regulated (P<0.01), indicating that AFFE exhibited potent anti-inflammatory activity. In HT22 cells, 250μg/mL AFFE significantly increased the production of the neurotransmitters γ-aminobutyric acid (GABA) and 5-hydroxytryptamine (5-HT) (P<0.01) and upregulated the mRNA expression of GABRA1, GABRA2, and 5-HT2A receptors. In the Drosophila melanogaster sleep deprivation model, male flies cultured in a medium containing 10% AFFE showed an 11.58% increase in total sleep duration, with no significant difference compared to the control group. LC-MS analysis identified 33 active components in AFFE, including 14 flavonoids. The study revealed a positive correlation between the increase in GABA and 5-HT production and the inhibition of NO, TNF-α, and IL-6 secretion, suggesting that the sleep-improving effects of AFFE were related to the anti-inflammatory properties of its flavonoid constituents.

Abstract:Sweeteners as food additives that serve as sugar substitutes, help to reduce the sugar content in foods and have been widely used in the food industry. The demand for low-calorie and natural sweeteners in the food industry is increasing. In order to understand the effect of sweeteners on human taste perception, the power changes of electroencephalograms (EEG) signal at multiple electrode sites in δ waves (1-4Hz), θ waves (4-8Hz), α waves (8-12Hz), and β waves (12-30Hz) under the stimulation of different sweeteners (fructose, sucrose, glucose, xylitol, aspartame, acesulfame, erythritol, steviol glycosides and sorbitol) were analyzed. The results showed that site F4 in the right frontal lobe and site P3 in the left parietal lobe were significantly enhanced under δ waves (P<0.05), while site C3 in the left central region and site P8 in the right posterior temporal lobe were significantly enhanced under θ waves (P<0.05), indicating that their crucial roles in emotional responses and emotional regulation. Although the sweetener spectrum signal changes in α waves and β waves were weaker, they also suggested an influence on the sensation of pleasure. Carbohydrate sweeteners, sugar alcohol sweeteners, and high-intensity sweeteners, as the most common types of sweeteners, could bind to receptors on the tongue to produce taste perception, which was then transmitted to the brain through complex signaling pathways. Power changes in EEG signals occur in the δ wave frequency band. Different types of sweeteners had varying effects on taste perception. Carbohydrate sweeteners induced changes in EEG signals in the δ wave, θ wave, and α wave bands. Sugar alcohol sweeteners influenced the δ wave and θ wave, while high-intensity sweeteners affected the δ wave, θ wave, α wave, and β wave. The differences of different electrode sites under different frequency signals reflected the complex processing mechanism of the brain for sweet stimulation. The research results had certain reference significance in diet behavior and emotion regulation.

Abstract:In order to improve the cyclic lipopeptide production of wild-type Bacillus velezensis G-1 and reduce the production cost, Alternaria alternata was used as the target, cheap rapeseed meal was used as the nitrogen source, and antifungal activity was used as the evaluation index. The effects on the synthesis of cyclic lipopeptides in B.velezensis G-1 was studied by single and compound mutagenesis methods of ultraviolet, microwave, ARTP(atmospheric room temperature plasma), NTG (nitroso guanidine), DES (diethyl sulfate) and EMS (ethyl methylsulfonate) mutagenesis. The aim was to establish an efficient mutagenesis method for high-yield cyclic lipopeptide mutants of B.velezensis G-1 and to select high-yield strain with rapeseed meal as nitrogen source. The results showed that the forward mutation rates of chemical mutagenesis were significantly higher than those of physical mutagenesis in six kinds of single mutagenesis methods. The forward mutation rate of chemical mutagenesis was higher for NTG and EMS, which were 59.97% and 59.40%, respectively. In physical mutagenesis methods, ARTP had a higher forward mutation rate of 31.37%. The combined treatment of NTG 150μg/mL, EMS 0.6mol/L, and ARTP 160s significantly increased the forward mutation rate of B.velezensis G-1. A high-yield cyclic lipopeptide mutant selected from the compound mutagenic strain could increase the production of cyclic lipopeptide by 2.33 times. The antifungal activity in vitro and in vivo increased by 52.20% and 96.55%, respectively. In this study, the combined mutagenesis method of NTG+EMS+ARTP could successfully obtain the B.velezensis G-1 mutant with high-yield cyclic lipopeptide, and further selected out mutants with high-yield cyclic lipopeptide by rapeseed meal. This study laid a theoretical foundation for the industrial application of the high-yielding B.velezensis G-1 mutants and its cyclic lipopeptides in the prevention of A. alternata infection after fruit and vegetable harvest.

Abstract:To identity the key saltiness enhancement taste compounds in yeast extracts, the taste profiles among three yeast extracts (FA31, KU012 and FA34) by quantitative descriptive analysis and their taste compounds content including free amino acids, organic acids, and nucleotides were determined by high performance liquid chromatography. The key saltiness enhancement taste compounds were screened by taste activity value analysis and saltiness enhancement evaluation of binary mixture analysis of taste-NaCl solution. Sensory evaluation results showed that the saltiness, the sweetness and sourness intensity of yeast extract KU012 were higher than those of FA31 and FA34 samples. The addition of yeast extract FA31 to 0.50g/L in a salt solution of 5.00g/L reduced the NaCl addition by 10% without affecting the saltiness intensity perception. The content of taste compounds in yeast extract KU012 was significantly higher than that of yeast extracts FA31 and FA34. The saltiness enhancement verification of 25 taste-presenting compounds with TAV over 1 in the yeast extracts by binary mixture analysis of taste-NaCl solution and saltiness enhancement evaluation. Results showed that 14 taste compounds had saltiness enhancement effects, among which aspartic acid, glutamic acid, alanine, citric acid, 5′-IMP, and 5′-GMP were the key saltiness enhancement compounds in yeast extract with significant saltiness enhancement effects. The results of the S-curve analysis showed that aspartic acid, glutamic acid, and citric acid could enhance salt perception through synergistic effects, while alanine, 5′-GMP, and 5′-IMP could enhance salt perception through additive effects.

Abstract:The effects of different pore sizes nanofiltration membrane on the volatile components and contents of Cymbopogon citratus extract were analyzed, which provided a technical reference for the preparation of natural flavors in Cymbopogon citratus. Five levels of nanofiltration membranes with different pore sizes of 10kDa, 1kDa, 500Da, 300Da, and 200Da were used for fine separation of Cymbopogon citratus extract, and gas chromatography-mass spectrometry (GC-MS) was used to analyze the volatile components in the filtrates separated by five kinds of nanofiltration membranes with different pore sizes. The odor activity value (OAV) was calculated and the cluster analysis was carried out. The results showed that a total of 56 volatile components were detected in Cymbopogon citratus extract, and the aroma types of the filtrates separated by different nanofiltration membranes were basically similar. With the decrease of the nanofiltration membrane pore size, the relative content of hydrocarbons, acids and ketones in filtrate decreased, while the relative content of alcohols and aldehydes increased, and the total content of compounds decreased gradually. The content of the same volatile component decreases with the decrease of the pore size of the nanofiltration membrane. By OAV analysis, 18 compounds such as (+)-citronellal, geraniol and citronellol were found to be the key contributors to the characteristic flavor of Cymbopogon citratus extract. The results of sensory similarity evaluation showed that the aroma types of the filtrates separated by different nanofiltration membranes were basically similar and difficult to be distinguished. However, the smaller the pore size of the nanofiltration membrane was, the higher the sensory identification of the filtrate was, and the easier it was to be distinguished. Nanofiltration membrane could effectively reduce the complexity of the flavor substance system of Cymbopogon citratus extract. It was hoped that the research could provide technical support and theoretical reference for the development of stable and practical Cymbopogon citratus essence products.

Abstract:To explore the influences of ultrasonic washing on the antioxidant systems of fresh-cut red cabbages, fresh-cut red cabbages were subjected to ultrasonic washing [frequency (28±2) kHz, power density 60W/L, frequency cycle time 400ms, and ultrasonic time 20min] and stored at 4℃ for 8d. The effects of ultrasonic washing on levels of reactive oxygen species (ROS), antioxidant enzyme activities, antioxidant contents, antioxidant capacities, and oxidative damages in fresh-cut red cabbages were examined. The results revealed that ultrasonic washing initially induced the production of superoxide anion radicals (O·-₂) and H₂O₂ in fresh-cut red cabbage during the initial storage period and subsequently reduced their accumulation during the later storage stages compared with the control group (distilled water washing). Ultrasonic treatment significantly enhanced the activities of antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT). The SOD and CAT activities of the ultrasound-treated samples increased by 31% and 26% compared with the control ones on Day 2, respectively. In addition, ultrasonic washing improved the contents of endogenous antioxidants, including ascorbic acid (AsA) and reduced glutathione (GSH), by enhancing the activities of ascorbate peroxidase (APX) and glutathione reductase (GR). In particular, the APX activity, GR activity, AsA content, and GSH content in fresh-cut red cabbages after ultrasonic washing were increased by 20%, 17%, 9%, and 9% on Day 4, respectively. Ultrasonic washing also improved the antioxidant capacities of fresh-cut red cabbages and effectively inhibited the increase of malondialdehyde and relative conductivity during the later storage stages. These findings indicated that the accumulation of ROS caused by ultrasonic washing actively activated the antioxidant defense mechanisms of fresh-cut red cabbages. Ultrasonic washing increased the antioxidant capacities and alleviated oxidative damage of fresh-cut red cabbages by increasing enzyme activities and antioxidant contents.

Abstract:In order to identify the origin of Lycium barbarum L. from Ningxia Zhongning, headspace-solid phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOF MS) was used to analyze the relative contents of volatile components in goji berries samples from Ningxia Zhongning, Xinjiang Jinghe, Gansu Jingyuan, Qinghai Xining, and Inner Mongolia Urad Front Banner. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to preliminarily complete the separation of Lycium barbarum L. from the five production areas, and the potential differential compounds of Lycium barbarum L. from Ningxia Zhongning compared with the other four production areas were found out through orthogonal partial least squares discriminant analysis (OPLS-DA). The results showed that there were 85 volatile compounds common to goji berries samples from five origins, and the compounds with relatively high proportion of relative peak area included methyl nonanoate, methyl hexanoate, 3-methylbutanal, etc. Through PCA and HCA analysis, it was found that Lycium barbarum L. samples from Ningxia Zhongning could be well separated with those from the other four origins, and 15 potentially different compounds were obtained through OPLS-DA analysis for Ningxia Zhongning sample compared with the others, of which 10 volatile compounds were detected only in Ningxia Zhongning sample, such as 6,10-dimethylundecan-2-one and (E,E)-2,4-hexadienal, while five compounds including ethyl octanoate and methyl butanoate were not detected in Ningxia Zhongning sample. This result could provide reference and technical guidance for the component analysis and origin identification of Lycium barbarum L from Ningxia Zhongning.

Abstract:In order to produce nutritious rice flour with high content of resistant starch and anti-digestive properties, the extrusion method was used to investigate the effects of high-temperature extrusion, low-temperature extrusion combined with ambient and low-temperature storage on the formation, structure and in vitro digestive properties of starch-lipid and starch-lipid-protein complexes in rice flour, using broken rice (BR) as raw material and with the addition of lauric acid (LA) and β-lactoglobulin (βLG). The optimal preparation method of rice flour containing high resistant starch was explored by taking the viscosity value of the pasting cooling peak, the differential thermal scanning enthalpies (ΔH) and the relative content of resist starch of in vitro digestion as the indicators for the formation effect of the complexes. The structural properties of the complexes were characterized by Fourier infrared spectroscopy bands and V-shaped peaks of X-ray diffraction. The results showed that different extrusion and storage treatments had a large effect on the pasting and thermal properties of rice flour, and the BR-LA-βLG group treated with low-temperature extrusion combined with low-temperature storage had the largest the pasting cooling peak viscosity value of 636 cP, indicating that the BR-LA-βLG treated with low-temperature extrusion-low-temperature storage produced the largest number of complexes, and had the highest ΔH and relative contents of resist starch in the thermal properties, which were 27.69% and 28.08%, respectively. The short-range ordering determination found that the infrared absorption peaks appeared at 1710cm-1 and 2855cm-1 in the BR-LA group and BR-LA-βLG group, and the intensity of the absorption peak of BR-LA-βLG group at 1710cm-1 was significantly lower than that of BR-LA group. The analysis of the crystal structure showed that the Va-type crystals were formed by starch with LA and βLG under different extrusion and storage temperatures. The crystallinity of the BR-LA-βLG group treated with low-temperature extrusion combined with low-temperature storage was the highest, which was 13.77%. The processing method of low-temperature extrusion combined with low-temperature storage could be used to obtain nutritious rice flour with relatively high content of resistant starch. The research aimed to enrich the source of staple food for diabetic people, and provide some reference for the raw material production of food with high content of resistant starch.

Abstract:Using Yunnan large leaf tea as raw material, alkaline oxidation crude theabrownins (TBs-a) and enzymatic oxidation crude theabrownins (TBs-e) were prepared by alkaline oxidation and enzymatic oxidation, respectively. The crude theabrownin extracted from Pu-erh ripe tea (TBs-f) through water extraction was used as a control. The main components, structural characteristics and non-volatile metabolites of crude theabrownins prepared by three different processes were analyzed. The results showed that the relative contents of the main components of the three crude theabrownins varied greatly. The relative contents of theabrownins in TBs-a and TBs-f were higher than those in TBs-e, while the relative contents of free amino acids and caffeine in TBs-f were higher than those in TBs-a and TBs-e. The scanning electron microscope showed that the surface of TBs-a was smooth and wrinkle-free, the surface of TBs-e had a large number of round pores, and the surface of TBs-f was rough. The X-ray diffraction analysis showed that all three crude theabrownins were amorphous polymers. The Zeta potential results showed that TBs-f had the smallest particle size and the best stability, TBs-a had the middle particle size and good stability, and TBs-e had the largest particle size and the worst stability. The thermogravimetric analysis showed that the thermal performance of the three crude theabrownins was good. The relative contents of non-volatile metabolites of the three crude theabrownins were quite different. And amino acids, organic acids, saccharide, alcohols and fatty acids were the main differential metabolites. Among them, amino acids accounted for a relatively high proportion in TBs-a and TBs-e, while organic acids and alcohols accounted for a relatively high proportion in TBs-f. There were significant differences among the three kinds of crude theabrownins in terms of main components, structural characteristics, and non-volatile metabolites. The study hoped to provide a theoretical basis and technical reference for the efficient preparation and rational utilization of theabrownins.