Abstract:Plant-based foods play a vital role in a healthy dietary structure for residents and serve as significant sources of the three major nutrients, dietary fiber, various vitamins, and minerals. With the improvement of living standards, people's pursuit of food has upgraded from “filling” to “eating well”. Accordingly, the flavor of foods (including plant-based foods) has become a key factor affecting consumer preferences. Especially, the concept of “biological flavor formation” under the action of biological media such as enzymes and microorganisms is gaining more and more attention and recognition from consumers. Food flavor produced by biological media such as enzymes and microorganisms is in line with consumers' expectation of natural, safe, non-additive or less additive food, so it is increasingly favored. Therefore, it is of great significance to understand the biological flavor formation mechanisms of plant-based foods systematically and comprehensively during growth, maturation, and processing, which contribute to flavor improvement and value enhancement of plant-based foods. By focusing on plant-based foods, the composition and flavor characteristics of key flavor substances based on the structural characteristics of flavor substances in plant-based foods, such as fatty compounds, aromatic compounds, heterocyclic compounds, and terpenes was systematically introduced. Furthermore, the biological flavor formation mechanism and recent advances of plant-based foods from both endogenous and exogenous perspectives at the molecular level were elaborated. Endogenous biological flavor formation primarily involved in the natural generation of characteristic flavor substances in plant-based foods through carbohydrate pathways, protein pathways, fatty acid pathways, and terpene pathways catalyzed by endogenous enzymes. Exogenous biological flavor formation relied on added enzymes or microorganisms to achieve the targeted synthesis of desired flavor compounds or the inhibition of undesirable flavor compounds through bio-catalysis and fermentation techniques. In the future, with the combination of multi-omics technology and interdisciplinary approaches, a deeper understanding of the biosynthetic pathways, regulatory mechanisms, and interactions of flavor substances in plant-based foods will be achieved. This will provide a scientific basis for product improvement and innovation in the food industry, facilitating the development and industrial-scale production of new products.

Abstract:The catering plays an important role in China's economy and society. With the development of society and the application of artificial intelligence, catering is evolving in the direction of diversification, specialization and intelligence. The development of China's catering industry was reviewed. The connotation and extension of Smart Catering 4.0 and the trend of new food science and technology and artificial intelligence technology utilized in this field were systematically analyzed. Computer vision combined with deep learning algorithms achieved the quality grading of raw materials. Digital twin technology not only can covert thousands of electronic recipes into process parameters, but also can simulate the cooking skills of culinary masters, put Chinese unique cooking techniques into robot cooking. The application of collaborative filtering recommendation algorithms, natural language processing, and face recognition technologies can quickly identify the customer and make personalized recommendations. This article summarized the current status and main technologies of smart catering, and proposed future directions, namely, focusing on health, basing on deliciousness, and centering on culture, with the aim of providing reference for the further development of the catering industry.

Abstract:Intelligent packaging indicator can provide consumers with effective information such as freshness, safety or environmental conditions (temperature, pH value, gas atmosphere) of packaged food, based on its ability to detect, sense and record changes in product environment, which is an extension of traditional packaging's ability to spread information. It also helps to improve the Hazard Analysis and Critical Control Point (HACCP) and Quality Analysis and Critical Control Point (QACCP) systems, which help to detect unsafe food on site, identify potential health hazards, and develop strategies to reduce or eliminate occurrence of food safety issues. Bio-based intelligent packaging system has attracted much attention because it uses degradable and renewable materials to visually display information related to the quality of packaged food in the supply chain to consumers, which conforms to the needs of circular economy and sustainable development. In this paper, the structural mechanism, functional adaptability types and functions of environment-friendly intelligent packaging indicators (pH sensing, time-temperature sensing and atmosphere sensing, etc.), which used natural pigment (anthocyanins, chlorophyll, curcumin and betalains, etc.) as sensitive element and bio-based polymer (polysaccharides, proteins, lipids and modified cellulose, etc.) as carrier, as well as the new trend and new progress in monitoring food quality, storage and transportation environment, were reviewed.

Abstract:To investigate the binding property between β-lactoglobulin (β-LG) and monascus pigments (Mps) under different pH values (2.6,6.2,7.1,8.2), four kinds of complex systems of β-LG and Mps were prepared, and the interactions between them were characterized using fluorescence spectroscopy, circular dichroism (CD) spectrum and molecular docking methods. At the same time, the antioxidant activity, thermal stability, and photo-stability of the complex (β-LG&Mps) were also determined. The results showed that the binding of Mps to β-LG could induce fluorescence quenching of β-LG under the experimental pH range. The complex of β-LG and Mps was mainly maintained through Van der Waals force, hydrophobic interaction and hydrogen bonds. However, no significant changes were observed in the secondary structures of β-LG. The DPPH free radical scavenging capacity of β-LG&Mps complex was higher than that of either β-LG or Mps, but lower than the sum of the two components, indicating that β- LG and Mps exhibited antagonistic effects on DPPH free radical scavenging. After forming complex with β-LG, compared with uncomplexed Mps, the retention rates of Mps in the complex increased by 58% (pH 6.2), 30% (pH 7.1) and 24% (pH 8.2), respectively, at 50℃. Additionally, the retention rates of Mps in the complex increased by 65% (pH 6.2), 43% (pH 7.1) and 43% (pH 8.2), respectively, under a light intensity of 600 Lux for 36 h at temperature 25℃. β-LG improved the thermal and photo-stability of Mps at pH values 6.2,7.1, and 8.2, however, the thermal stability and photo-stability of Mps were poor under the acidic condition (pH 2.6). The study explored the improvement of the stability of monascus pigment through the interaction of food components, to provide beneficial references for the development of monascus pigment related products.

Abstract:Anthocyanin can be used as a natural colorant in food systems such as beverages, but it is susceptible to degradation by ascorbic acid in foods. Chitosan can be added to beverages for thickening and stabilization, but it can have an effect on the stability of anthocyanin. The effect of different concentrations of chitosan on the stability of anthocyanin in a model beverage system was investigated, and the improvement effect of sinapic acid addition on stability of anthocyanin in the presence of chitosan was analysed. The stability of black rice anthocyanin in different systems was analyzed by accelerated storage experiments and degradation kinetic methods, and the mechanism of action of sinapic acid in improving the stability of black rice anthocyanin in chitosan systems was analyzed by molecular dynamics simulations. The results showed that a single chitosan led to a decrease in the color stability of anthocyanin in the 7d accelerated experiment. Sinapic acid significantly improved the color stability and content retention of black rice anthocyanin in chitosan-containing model beverages. Degradation kinetic analysis showed that the addition of sinapic acid in the chitosan experimental group at a chitosan mass concentration of 5 mg/mL increased the half-life t1/2 of the anthocyanin by 2.3 fold and reduced its degradation rate constant K by 0.1523d-1. Molecular dynamics simulation results showed that the presence of free sinapic acid promoted more anthocyanin molecules to approach the chitosan-sinapic acid complex and form a more stable binding. Therefore, the addition of sinapic acid to model beverages containing chitosan could achieve a protective effect on anthocyanins, hoping to provide some theoretical basis for the application of phenolic acid and the optimization of functional chitosan model beverages in the futture.

Abstract:To study effects of protein-protein interactions on solubility, structure and emulsion properties of pine kernel protein (PKP), PKP and whey protein concentrate (WPC) were used as research objects, and PKP-WPC complex protein was prepared by pH-cycle method. The structure and surface properties of complex protein were analyzed by SDS-PAGE, intrinsic fluorescence spectra, ultraviolet-visible spectra, circular dichroism, fluorescent probe and ζ- potential, and then emulsions with oil phase volume fractions of 3%, 10% and 50% were prepared using PKP-WPC complex protein as material, respectively. Finally, emulsion properties were tested. The results showed that when mass ratio of WPC addition to PKP was 1.0∶1.0 and pH of system went through a pH-cycle from 7.0 to 12.0 and back to 7.0, water solubility of PKP improved from 48.53% to 92.43%. SDS-PAGE results showed that PKP-WPC complex protein completely retained subunits of PKP and WPC. Intrinsic fluorescence spectra, ultraviolet-visible spectra and circular dichroism showed that electrostatic interaction, hydrophobic interaction and hydrogen bond were major forces driving the interaction between PKP and WPC, and interactions of PKP and WPC endowed complex protein with high structural toughness and resistance to acid-induced conformational folding. The addition of WPC changed secondary structure of PKP, the amount of α-helix, β-turn and random coil structures increased, while relative content of β-sheet structures decreased. PKP-WPC complex protein had higher surface charges (-34.74mV) to resist protein aggregation. Compared with emulsions prepared from PKP, emulsions prepared from PKP-WPC showed reduced mean particle diameter and creaming index, increased absolute value of ζ-potential, and significantly improved stability. Emulsions properties varied considerably depending on oil phase volume fraction. The composite emulsion with 3% oil phase volume fraction had small and uniformly distributed droplets, and its stability was better than composite emulsion with 10% and 50% oil phase volume fraction. The study improved PKP solubility by adding WPC through pH-cycle method, and obtained PKP emulsions with better stability. The study could provide a theoretical basis for the development of new protein products, broaden application of pine kernel protein in processed foods, and promote development of PKP-WPC double protein emulsion research.

Abstract:Soyasaponins are abundantly present in soybean germ, hypocotyl, and other parts, especially in defatted soybean meal, which can be produced as a high-value-added product to improve the utilization of by-products in soybean oil processing. Soyasaponins belong to pentacyclic triterpenoid compounds and are a type of dammarane-type saponin composed of hydrophobic aglycone and hydrophilic sugar group. They possess certain amphiphilic properties and various physiological activities, including anti-tumor, anti-inflammatory, antioxidant, immune-modulating, and hepatoprotective effects. In recent years, the research areas of soyasaponins have been continuously expanded from activity verification to molecular mechanisms, producing a number of forward-looking achievements. Soyasaponins with different structures and types exhibit different physiological activities and mechanisms of action, and related research provided a theoretical basis for the application of soyasaponins in food and medicine. This article focused on the latest research progress on the structure and classification, physiological activities, and structure-activity relationships of soyasaponins, analyzed the influence of processing methods on the structure of soyasaponins, summarized the mechanisms of soyasaponins in exerting physiological activities and their applications based on physiological activities, and illustrated the problems that need to be addressed in the future application of soyasaponins, aiming to provide a theoretical basis for further research and development of soyasaponins.

Abstract:Volatile sulfur-containing compounds (VSCs) have the characteristics of intensive aromas and low thresholds, which have important impacts on the flavor of foods. However, concentrations of most VSCs in food are below the detection limit of gas chromatography-mass spectrometry (GC-MS), which are difficult to be identified and recognized. Soy sauce aroma-type is a main aroma-type of Baijiu in China, Wuling soy sauce aroma-type Baijiu, which produced in Hunan, is one of important representatives. In order to further explore the composition of important trace VSCs in soy sauce aroma-type Baijiu in China, head space solid phase micro-extraction combined with comprehensive two-dimensional gas chromatography-sulfur chemiluminescence detector (GC×GC-SCD) was used in this study to analyze the VSCs in 6 kinds of Wuling soy sauce aroma-type Baijiu samples. A total of 27 VSCs were identified in this study, of which 19 VSCs were coexistent and 8 VSCs were not coexistent in 6 kinds of Wuling soy sauce aroma-type Baijiu samples, mainly including 4 kinds of thiols, 6 kinds of thioesters, 5 kinds of thioethers, 5 kinds of thiazoles, 6 kinds of thiophenes and 1 kind of thiane. The external standard curve method was used for quantitative analysis of 23 VSCs of which signal to noise ratio was greater than 100. Based on quantitative analysis results, principal component analysis and orthogonal partial least squares discriminant analysis were used to demonstrate the differences in the VSCs contents of 6 kinds of Wuling soy sauce aroma-type Baijiu samples. Fourteen VSCs with variable projection value greater than 1 were screened out as the difference components to distinguish the flavor characteristics of the 6 kinds of Wuling soy sauce aroma-type Baijiu samples. It was hoped that the study could provide data reference for the blending of soy sauce aroma-type Baijiu and provide help for Baijiu enterprises to regulate the production process and improve product quality.

Abstract:The inhibition effect of Lactobacillus paracasei (L.paracasei) ET-22 live bacteria, known for its efficacy in preventing dental caries, and postbiotic components (heat-inactivated bacteria and secretions) on Candida albicans was investigated. After evaluating the antioxidant capacity of L. paracasei ET-22 live bacteria and its postbiotic components and the inhibition rate of Candida albicans hyphae transformation, an oral candidiasis model of ICR mice was established by injection of immunosuppressants and application of Candida albicans. Before and after modeling, L. paracasei ET-22 live bacteria with a dose of 10⁹CFU/mL and corresponding postbiotic components were continuously administered through drinking water for 18d to study the effects of L. paracasei ET-22 on the morphology of mouse tongue tissue and the expression of inflammatory factors. At a concentration of 10⁹CFU/mL of L.paracasei ET-22 live bacteria, the live bacteria exhibited the highest inhibition rate of 37.84% against the budding of Candida albicans. The heat-inactivated bacteria and secretions in the postbiotic components showed inhibition rates of 17.50% and 28.00%, respectively. In animal models, after intervention with live bacteria and postbiotic components, the concentration of IFN-γ in the serum was significantly reduced. In the secretion group, the content of IFN-γ and TNF-α in the tongue tissue was significantly reduced, while in the live bacteria group, only TNF-α content was significantly reduced. The live bacteria and heat-inactivated bacteria groups showed a significant increase in the CCL20 chemokine content and the richness and diversity of coated tongue microbiota. The histopathological sections showed that the ET-22 live bacteria and secretion group significantly improved the looseness of the mouse tongue epithelium and inflammatory cell infiltration, and the heat-inactivated bacteria group had a positive effect on the shedding of papillae and tongue epithelium. The experimental results showed that ET-22 could regulate oral microbiota composition and inhibit harmful bacteria to oral through alleviating the inflammatory infiltration and metastasis of tongue tissue. The study indicated that ET-22 could decrease the risk of oral candidiasis and could be further developed for oral probiotic food with the function of oral health caring.

Abstract:The LuxS/AI-2 quorum sensing (QS) system mediates intraspecific and interspecific signals of lactic acid bacteria, among which autoinducer-2 (AI-2) is crucial for probiotic activities of lactic acid bacteria, including environmental stress tolerance, adhesion and colonization ability. However, the regulatory effect of LuxS/AI-2 QS system in the resistance of Lactobacillus plantarum to various environmental stresses still needs to be systematically studied. The production of the signaling molecule AI-2 and the transcription of QS key genes luxS and pfs of Lactobacillus plantarum KLDS 1.0328 under environmental stress were analyzed by biological study and real-time fluorescence quantitative polymerase chain reaction. The results showed that acid stress could induce the production of signal molecule AI-2 and the transcription of luxS and pfs was significantly promoted under strong acid and alkali stress (P<0.05). Low temperature 25℃, high temperature 50℃ and hyperosmotic stress induced by mass fraction 6.0% NaCl and mass fraction 3.0% NaCl+3.0% KCl could significantly inhibit cell proliferation, acid production and signal molecule AI-2 production. The transcription of luxS and pfs was up-regulated under low temperature stress at 25℃. The transcription of luxS and pfs was up-regulated with the increase of hypertonic stress. Furthermore, L. plantarum KLDS 1.0328 was induced to produce more signal molecule AI-2 by nutrient stress. With the aggravation of nutrient stress, the transcription of luxS was significantly up-regulated. The transcription of luxS and pfs reached the highest level when the nutrient volume fraction was 20%, while the transcription of pfs was significantly inhibited when the nutrient substance was diluted to volume fraction 40%-60% (P<0.05). These results indicated that LuxS/AI-2 QS system had different variation patterns under various environmental stresses, and played an important role in the stress resistance of L. plantarum KLDS 1.0328.

Abstract:Protein degradation during fermentation and maturation of Dahe black pig ham results in abundant bioactive peptides. In order to investigate whether there were α-glucosidase inhibitory peptides in Dahe black pig ham and its activity, ham peptides of different molecular masses were prepared by ultrafiltration separation, and α-glucosidase inhibition rate was used as an index to identify, screen and study the activity of peptides in Dahe black pig ham by peptidomics combined with bioinformatics analysis. The results showed that the peptide of Dahe black pig ham with molecular weight less than 3kDa had good α-glucosidase inhibitory activity. A total of 143 peptides were identified from Dahe black pig ham, mainly derived from myosin, troponin and β-enolase. The further screened peptide IEEALGDK showed a good α-glucosidase inhibitory activity (IC₅₀=1.42mg/mL). The results of BIOPEP-UWM search revealed that the peptide IEEALGDK was a novel bioactive peptide. Peptide stability studies have shown that the IEEALGDK peptide has good thermal stability, acid and alkali resistance and gastrointestinal digestive stability. Molecular docking results showed that the peptide IEEALGDK mainly exerted its active effects by occupying the active residue sites of α-glucosidase, Arg594, Arg727, Arg799 and Arg467 through hydrogen bonding and hydrophobic interactions. The IEEALGDK peptide derived from Dahe black pig ham had good α-glucosidase inhibitory activity and the study aimed to provide a theoretical support for the further development and use of the Dahe black pig ham peptide.

Abstract:In order to study the optimal enzymatic hydrolysis process for preparing thermal reaction bovine bone flavoring, bovine bone extract (BBE) was used as raw material, and compound enzyme was selected. The effects of enzymatic hydrolysis temperature, enzymatic hydrolysis time, compound enzyme addition amount and compound enzyme addition ratio on the degree of hydrolysis of enzymatic hydrolysate and the sensory score of thermal reaction bovine bone flavoring prepared by Maillard reaction of enzymatic hydrolysate with sugar, amino acid and other raw materials were investigated by single factor and response surface test. The mass ratio of free amino acid was determined by high performance liquid chromatography (HPLC), and the mass ratio of key odor compounds of thermal reaction bovine bone flavoring prepared before and after enzymatic hydrolysis of BBE was analyzed by comprehensive two-dimensional gas chromatography-olfactometry-mass spectrometry (GC×GC-O-MS). The results showed that the better enzymatic hydrolysis process of BBE was enzymatic hydrolysis temperature of 50℃, enzymatic hydrolysis time of 4h, enzyme addition amount of 1250U/g, and the ratio of compound flavor protease to compound protease was 3∶2. Under this condition, the sensory score was 8.17. Compared with BBE, the mass ratio of 15 free amino acids in the enzymatic hydrolysate increased significantly. The odor profile and taste profile of BBE and enzymatic hydrolysate were measured by electronic nose and electronic tongue. It was found that the nitrogen oxide odor characteristics of enzymatic hydrolysate were enhanced, and the umami, richness and salty taste characteristics of enzymatic hydrolysate were more obvious. The key odor compounds of thermal reaction bovine bone flavoring prepared by BBE and enzymatic hydrolysate were analyzed by solid phase microextraction (SPME) combined with GC×GC-O-MS. A total of 164 volatile odor compounds were identified, including 27 aldehydes, 30 ketones, 12 alcohols, 16 acids, 7 sulfur-containing compounds, 10 esters, 18 pyrazines, 10 furans, 6 thiazoles, 4 thiophenes and 24 other compounds. Through gas chromatography-olfactometry (GC-O) analysis, 74 odor-active compounds were detected. There were 22 key odor compounds with odor activity value (OAV) greater than 1. The most important key odor compounds in the thermal reaction bovine bone flavoring prepared by BBE and enzymatic hydrolysate both were bis(2-methyl-3-furanyl) disulfide (OAV was 13079 and 8053, respectively). Compared with the thermal reaction bovine bone flavoring prepared by BBE, 5 new key odor compounds, (E,E)-2,4-decadienal, 2-methyl-3-furanthiol, methyl furfuryl disulfide, S-methyl thiohexanoate and β-caryophyllene appeared in the thermal reaction bovine bone flavoring prepared by enzymatic hydrolysate. The purpose of this study was to provide a theoretical basis for the enzymatic hydrolysis process in the industrial production of thermal reaction bovine bone flavoring.

Abstract:Compared with low-moisture textured proteins with poor texture and taste, high-moisture textured vegetable proteins (HMTVP) show a fibrous structure and taste similar to animal meat. Being known as a new generation of vegetarian meat products, HMTVP are becoming ideal substitutes for animal protein. Dual-screw extrusion technology was used to prepare high moisture textured proteins taking pea protein isolate (PPI) as material. The effects of process parameters (moisture content, cooking temperature, feeding speed, and screw speed) on the macro and microstructure, texture, and sensory properties of the extrudates were explored. At the same time, an orthogonal experiment was designed and principal component analysis was used to optimize the operating parameters of the extrudates closest to animal meat. The results showed that the moisture content was the key factor to improve the texturization degree and texture of PPI extrudates. The increase of moisture content increased the texturization degree and color of PPI extrudates, and significantly reduced the hardness and chewiness of the extrudates. When the moisture content was too high (65%) or too low (45%), extrudates showed poor fibrous structures. When extruded at 140℃ to 160℃, the PPI extrudates exhibited the better texturization degree, taste, appearance and color. With the increase of the screw speed, the texturization degree of extrudates significantly decreased first and then increased. When feeding speed was increased, the hardness and chewiness of the extrudates significantly increased first and then decreased, while texturization degree decreased first and then increased. Through orthogonal experiment combined with principal component analysis, the optimal processing parameters established were by taking the texture parameters of beef cucumber strips as the target parameter moisture content of 55%, cooking temperature of 160℃, screw speed of 175r/min, and feeding speed of 7g/min. The results aimed to provide technical support for the quality control of high-moisture textured vegetable proteins.

Abstract:Cyperus esculentus is a high-quality and healthy crop, rich in nutrients. Insoluble dietary fiber of Cyperus esculentus was prepared via an enzymolysis method. Compared with the commercial soybean dietary fiber, the physicochemical, structural and emulsifying properties of Cyperus esculentus insoluble dietary fiber (CEIDF) were studied. The results showed that the CEIDF had a better water holding capacity [(14.45± 0.19)g/g], oil holding capacity [(8.21±0.06)g/g] and expansion capacity [(14.23±0.12)mL/g], than those of soybean dietary fiber. The average volume diameter of the CEIDF was (64.47±0.18)μm, which was 56.65% of that of soybean dietary fiber. The results of low field NMR indicated that CEIDF had more bound water, while the soybean dietary fiber had more free water. The thermogravimetric analysis showed that CEIDF had a less weight loss and a greater thermal stability compared to the soybean dietary fiber. In terms of emulsifying properties, with the increased concentration of CEIDF, the emulsion particle size increased significantly. Under the same concentration of dietary fiber, the particle size of the emulsion prepared from CEIDF was significantly lower than soybean dietary fiber which indicated that the stability of the emulsion prepared from CEIDF was better than the emulsion prepared from soybean dietary fiber. Under the same concentration, the viscosity of CEIDF was lower than that of soybean dietary fiber, while the energy storage modulus and loss modulus of emulsion prepared from 4% CEIDF were the highest. This study aimed to provide a theoretical basis for the development and utilization of CEIDF.

Abstract:In the study, starch-rich sorghum was used as raw material to improve the production efficiency of caproic acid by two-step anaerobic fermentation. The first step was to inoculate caproic acid compound bacteria, inoculate Lactobacillus acidophilus TYCA06, and add Saccharomyces cerevisiae to produce butyric acid fermentation broth, lactic acid fermentation broth and ethanol fermentation broth. The second step was to mix butyric acid fermentation broth, lactic acid fermentation broth and ethanol fermentation broth, and then inoculate caproic acid compound bacteria to produce caproic acid by anaerobic fermentation. The results showed that by optimizing the fermentation process of butyric acid fermentation broth, lactic acid fermentation broth and ethanol fermentation broth, the butyric acid and acetic acid yield in butyric acid fermentation broth reached 20.16g/L and 8.47g/L, and the starch conversion rate reached 76.02%. The lactic acid yield and lactic acid yield rate in lactic acid fermentation broth reached 11.41g/L and 42.48% respectively. The ethanol yield in ethanol fermentation broth reached 95.06%. Continuing to optimize the caproic acid fermentation process, it was found that when ethanol fermentation broth and lactic acid fermentation broth were used as electron donors at the same time, the yield and yield rate of caproic acid were significantly increased, reaching 4.15g/L and 75.2mg/g, respectively, and when the mass concentration ratio of ethanol to lactic acid added in ethanol fermentation broth and lactic acid fermentation broth was 2∶1, the yield and yield rate of caproic acid reached the highest, reaching 6.65g/L and 99.78mg/g, respectively. According to the correlation analysis between microorganisms and caproic acid in the process of caproic acid fermentation, Caproiciproducens, Clostridium_sensu_stricto_12 and Pseudoclavibacter were positively correlated with caproic acid content in the fermentation process. Among them, Caproiciproducens was continuously enriched with fermentation, and the relative abundance reached 37.81% in the later stage of fermentation, which was the main contributor to the formation of caproic acid. It was hoped that the study could provide a theoretical basis for the production of caproic acid by two-step anaerobic fermentation of sorghum without exogenous electron donor, and provide a new idea for expanding the resource utilization of sorghum.