• Volume 41,Issue 3,2023 Table of Contents
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    • >Special Edition
    • Development Status and Existing Problems of Soybean Food Industry in China

      2023, 41(3):1-8. DOI: 10.12301/spxb202201131

      Abstract (511) HTML (900) PDF 5.11 M (1440) Comment (0) Favorites

      Abstract:Soybeans and soybean food are related to national food security, and nutrition and health of the public. Rationalizing and regulating the development relationship between soybean raw material production, food processing and utilization and food manufacturing modernization were very important for building a modern powerful socialist with Chinese characteristics. China is an important soybean producer, with total output always ranking fourth in the world, and more than 85% of domestic soybeans were used for food processing every year. However, at present, the development of China's soybean food industry were still many problems in the industrial chain, supply chain and value chain. In terms of raw material utilization, although the demand of domestic soybeans guarantees the supply of soybean food industry, the quality was difficult to meet the demand for special soybean raw materials. The mixed planting, mixed harvest and mixed use of soybeans were still the main problems faced by soybean food processing enterprises. In order to maintain a competitive position in the future, domestic specific soybean raw materials for food must have a clear positioning in variety selection, planting management, and production and marketing quality control. It was necessary to establish a unified and coordinated production, processing and sales system. And it was also necessary to improve China's soybean raw material standard system and to improve the raw material labeling and promotion system with unified soybean variety names and processed product commodity names. In terms of industrial processing, the modernization of soybean food processing had made great progress in recent years, but the in-depth excavation of traditional processes and the development of new technologies and new products were insufficient and the market segmentation of products with different functional demands for nutrition and health needed to be strengthened. In the future, the development of new technologies, new products, and new equipment for soybean food processing in China must take the road of combining with digital technology, continuously improve the digital and intelligent level of soybean food processing, and realize green manufacturing and modernization in the entire industrial chain of raw materials, storage and transportation, product production, manufacturing and circulation.

    • New Plant-Based Milk Substitutes:Nutritional Properties, Current Processing Status and Future Challenges

      2023, 41(3):9-18. DOI: 10.12301/spxb202300181

      Abstract (607) HTML (805) PDF 7.39 M (648) Comment (0) Favorites

      Abstract:Driven by vegetarianism, dietary nutrition, environmental friendliness and other factors, plant-based diet, which is an alternative to animal derived foods, has developed rapidly worldwide in recent years. As an important branch, plant-based milk substitutes have received huge attention from scientific research, industry, and consumers. First, the development and research status of the plant-based milk substitutes industry both domestically and internationally was reviewed. Then, a comprehensive summary of the scientific research progress and industrial development status of plant-based milk substitutes with regard to their nutritional and functional properties, processing technology, and quality improvement was provided. The nutritional composition of cow's milk and common plant-based milk substitutes were compared and analyzed. The preliminary performance of plant-based milk substitutes in health efficacy research was presented. The key technical aspects of raw material pretreatment, grinding, enzymatic digestion, homogenization, and sterilization involved in the processing of plant-based milk substitutes and their effects on product quality were systematically summarized. The common problems, quality challenges, and improvement measures in the stability, flavor and taste, and nutritional quality of these products were discussed. Finally, some suggestions were presented for the scientific and technological innovation and future development of the industry in terms of raw material processing suitability, green and advanced processing technologies selection, and new plant-based resources mining, with a view to providing references for the sustainable development of the new industry of plant-based milk substitutes.

    • >Expert Forum
    • Liquid-Liquid Extraction Technology for Aroma and Flavor Compounds in Traditional Fermented Beverages and Seasonings

      2023, 41(3):19-27. DOI: 10.12301/spxb202300257

      Abstract (1476) HTML (527) PDF 6.11 M (589) Comment (0) Favorites

      Abstract:The aroma and flavor of traditional fermented beverages and seasonings is an important aspect of determining their quality. The use of modern flavor chemistry theory and methods to study their aroma and flavor has been recognized by the industry. One of the most important operations in the series of studies on aroma and flavor compounds is the isolation or extraction of flavor compounds, which involves the isolation of flavor interfering substances or matrices. If the target flavor compounds could not be extracted at the sampling, the correct results could not be obtained. Most isolation and extraction techniques can be used for this process, but some researchers have found that liquid-liquid extraction technology could be the best method for extracting and isolating the aroma and flavor of traditional fermented beverages and seasonings. Before liquid-liquid extraction, the pre-treatment methods of solid, liquid, semi-liquid, and bioactive raw materials are different. The principle for selecting the extraction solvent is that the characteristic aroma and flavor compounds, all flavor compounds, and target flavor compounds of the original sample must be extracted. The selection of liquid-liquid extraction methods should consider the volatility, boiling point, polarity, stability, concentration, distribution in the sample, and other characteristics of the flavor compounds to be tested. The ideal liquid-liquid extraction result is the simultaneous extraction of polar and non-polar compounds, without causing thermal degradation and redox of flavor compounds, without changing pH value, and without significant loss of high volatile compounds. Due to the presence of compounds, such as proteins, sugars, and fats in the matrix, emulsification often occurs during liquid-liquid extraction. Demulsification could be achieved through methods such as salt addition, ultrasound, freeze-centrifugation, solvent assisted flavor evaporation (SAFE), glass wool filtration, phase filtration, addition of solvents with different polarity, and addition of precipitant. Due to the complex composition of aroma and flavor compounds in the extraction solution, direct GC-MS or GC-O analysis could result in overlapping peaks of compound coeluting and interference of aromas. The extraction solution could be fractioned into acidic, alkaline, and neutral fractions, and further analysis could be carried out by combining chromatographic separation techniques such as silica gel column or normal phase column. The systematic reviews of the liquid-liquid extraction technology of traditional fermented beverages and seasonings flavors could inspire the research ideas of flavor researchers.

    • Research Progress on Aroma Compounds in Wine

      2023, 41(3):28-40. DOI: 10.12301/spxb202300264

      Abstract (721) HTML (724) PDF 9.26 M (619) Comment (0) Favorites

      Abstract:Aroma is an important indicator of wine sensory evaluation and also an important factor for affecting the quality style and consumer orientation of wine. Aroma compounds in wines with various styles are complex and diverse, which are affected by grape varieties, fermentation technologies, aging conditions and other factors. Maintaining varietal typicality, enhancing fermentative odorants and improving aging flavor quality of wine have always been the goals of wine flavor research, making it crucial to comprehensively analyze the formation pathway and aroma presentation mechanisms of odorants in wine. In this review, the formation patterns of varietal odorants and fermentative odorants and the regulatory mechanisms of winemaking processes on the production of wine odorants were discussed from the perspective of fermentation regulation, and the relationships between related flavor enzymes and aroma precursors with aroma compounds were introduced. Meanwhile, the forming path of aging aroma were discussed, and the influencing mechanism of different oak products and aging technologies on shaping wine aging aroma characteristics was summarized. Additionally, the detection technologies of odorants and the research methods of the synergy effect between odorants were briefly described, the effects of key odorants interaction and matrix effect on wine flavor perception were analyzed. Finally, future research directions and trends were proposed, with a view to provide theoretical basis and technical support for the establishment of flavor-oriented wine technology control methods.

    • >Special Studies
    • Regulatory Effect and Mechanism of Konjac Mannan Oligosaccharides on Atherosclerosis in ApoE-/- Mice

      2023, 41(3):41-53. DOI: 10.12301/spxb202200591

      Abstract (553) HTML (503) PDF 15.12 M (622) Comment (0) Favorites

      Abstract:Konjac mannan oligosaccharides (KMOS) have a variety of beneficial effects on human health, but their regulator effects on atherosclerosis (AS) and the involved molecular mechanisms have not been well understood. In this study, AS model was established by feeding ApoE-/- mice with high fat diet (HFD) for 14 weeks and used for investigating the effects of KMOS intervention on aortic lipid accumulation, serum lipid, and inflammatory factors. The regulatory effect of KMOS on gut microbiota of AS mice was analyzed by using Illumina high-throughput sequencing technology. The results showed that KMOS supplementation significantly inhibited the increase of body and liver weight induced by HFD. Comparing with HFD group, the area ratio and total area of plaque lesions in aortic sinus induced by HFD was reduced by 57.4% and 57.9%, respectively after KMOS treatment. The total serum cholesterol levels and low-density lipoprotein cholesterol levels were decreased by 21.1% and 31.1%, whereas the high-density lipoprotein cholesterol level was significantly increased by 63.0% after KMOS treatment. Meanwhile, lipid accumulation in the liver of HFD induced ApoE-/- mice was significantly improved. The levels serum inflammatory factors (tumor necrosis factor α, interleukin-6, interleukin-1β, and monocyte chemotactic protein-1) were reduced by KMOS, compared with AS model group. Moreover, the expression of genes associated with liver cholesterol reverse transport was significantly increased by KMOS. Furthermore, KMOS inhibited the dysbiosis of gut microbiota in ApoE-/- mice induced by HFD with increased relative abundances of g_norank_f_Lachnospiraceae, g_Alistipes, and g_norank_f_Ruminococcaceae. The production of short chain fatty acids in the cecum was promoted and the expression of intestinal tight junction proteins was increased by KMOS to prevent the impairment of intestinal barrier function. Thus, KMOS could alleviate the development of AS in ApoE-/- mice induced by HFD through the regulation of cholesterol metabolism and gut microbiota. This results aimed to provide theoretical basis for development of KMOS related functional food.

    • Effects of Phycocyanin on Glucose Metabolism in Insulin-Resistant HepG2 Cells

      2023, 41(3):54-63, 84. DOI: 10.12301/spxb202200839

      Abstract (717) HTML (534) PDF 8.72 M (551) Comment (0) Favorites

      Abstract:To investigate the mechanism of phycocyanin (PC) on improving insulin resistance (IR) in vitro, high concentration of insulin was used to induce IR model. HepG2 cells were treated with five insulin concentration gradients (10-9, 10-8 , 10-7, 10-6, 10-5μmol/L) and six time gradients (0,12, 24,36, 48,72h), respectively. According to the results of glucose consumption and cell viability, the optimal concentration and time of insulin resistance model of HepG2 (IR-HepG2) cells were determined. After PC intervention, glucose consumption, glycogen synthesis and cell viability of normal and IR-HepG2 cells were detected, respectively. RT-qPCR and Western blot were used to investigate the possible mechanism. The results showed that IR-HepG2 cells was optimally established with 10-7μmol/L insulin treatment for 36h. Different concentrations of PC could promote glucose consumption of IR-HepG2 cells. PC could up-regulate the transcription levels of IRS1, IRS2, GLUT1 and GLUT4 genes in both normal and IR-HepG2 cells, and increased the phosphorylated protein expression levels of IRS1, AMPK, GSK-3β and AKT. PC might significantly promote glucose consumption in IR-HepG2 cells by activating IRS1/AKT signaling pathway and increasing the phosphorylation of AMPK, also activating expression of GLUT1 and GLUT4 genes ecoding glucose transporter,and accelerate glucose utilization and improve insulin resistance in IR-HepG2 cell. This study indicated that PC had a potential role in preventing or improving hepatic insulin resistance of type 2 diabetes mellitus.

    • Mechanism and Effect of Yam Polysaccharides on Insulin Resistance in Type 2 Diabetes Mice

      2023, 41(3):64-71. DOI: 10.12301/spxb202200873

      Abstract (908) HTML (527) PDF 8.42 M (520) Comment (0) Favorites

      Abstract:To study the mechanism of yam polysaccharide on insulin resistance in type 2 diabetes mellitus (T2DM) mice, C57BL/6 mice was selected and randomly assigned to the following groups:normal group, model group, low dose yam polysaccharide group, medium dose yam polysaccharide group, high dose yam polysaccharide group and metformin group. T2DM mice model was induced by feeding high fat diet combined with streptozotocin (STZ). After 6 weeks of continuous administration, serum were collected and fasting blood glucose (FBG), fasting insulin (INS), insulin resistance index (HOMA-IR) and insulin tolerance test (ITT) were determined. The abundance of intestinal flora was detected by 16S rRNA gene high-throughput sequencing, and the content of feces short-chain fatty acids (SCFAs) were detected by GC-MS. It was found that the level of serum FBG, FINS and HOMA-IR in each group of yam polysaccharide decreased significantly (P<0.01 ). The total amount and diversity of intestinal bacterial species in the yam polysaccharide group increased compared with type 2 diabetes mice. Firmicutes/Bacteroidetes ratio and Proteobacteria decreased at phylum level, Lactobacillus and Akkermansia significantly increased at genus level, while Enterobacter and Desulfovibrio significantly decreased compared with the model group. Compared with the model group, the intestinal SCFAs content of yam polysaccharide group were increased, and the upward trend of propionic acid and butyric acid was significant. The results showed that yam polysaccharide could improve glucose and lipid metabolism disorder and insulin resistance in T2DM mice, which might be related to the increase of total intestinal bacterial species and diversity, the change of bacterial community proportion and the increase of SCFAs. The aim of this study was to provide theoretical basis for yam polysaccharides development and utilization.

    • Effect and Mechanism of Pepsin-Solubilized Collagen Peptides from Lophius litulo Skin on Non-Alcoholic Fatty Liver Disease in Mice

      2023, 41(3):72-84. DOI: 10.12301/spxb202200938

      Abstract (544) HTML (504) PDF 18.89 M (594) Comment (0) Favorites

      Abstract:To investigate the effect and mechanism of pepsin-solubilized collagen peptides from of Lophius litulo skin (PSCP) on high fat diet (HFD) induced non-alcoholic fatty liver disease (NAFLD) in C57BL/6 mice. Forty-eight C57BL/6 mice were fed with high-fat diet for 4 weeks to induce the nonalcoholic fatty liver disease model. The mice were then treated with metformin, low, medium and high dose PSCP for 6 weeks. The serum physiological and biochemical indexes, liver oxidative stress level, liver histopathology changes and protein expression levels of the mice in each group were measured respectively. The experimental results show that compared with the model group, total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL-C), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels in the positive drug group and high dose PSCP group were significantly decreased (P<0.05), and HDL-C levels were significantly increased (P<0.05). glutathione (GSH), superoxide Dismutase (SOD), and catalase (CAT) activities in liver of the positive drug group, middle dose and high dose PSCP groups were significantly increased (P<0.05), while malondialdehyde (MDA) contents were significantly decreased (P<0.05). Hematoxylin-eosin (HE) staining and transmission electron microscopy showed that the liver structure of the positive drug group and PSCP groups was significantly improved. The results of protein immunoblotting showed that, compared with the normal group, the protein expression levels of AMPKα, p-AMPKα, and IκBα in the liver of model group were significantly decreased (P<0.05), while the protein expression levels of SREBP-1, p65, p50, and IKKα were significantly increased (P<0.05). However, after administration of the positive drug and PSCP, the protein expression levels of AMPKα, p-AMPKα, and IκBα were increased, and the protein expression levels of SREBP-1, p65, p50, and IKKα were decreased. The result showed that PSCP could effectively improve the biochemical indices of NAFLD mice and restore the liver tissue structure, and the mechanism might be related to AMPK/NF-κB pathway transduction.

    • >Foundational Research
    • Diversity and Key Biological Activities of Endophytic Bacteria in 4 Varieties of Hainan Noni Fruit

      2023, 41(3):85-97. DOI: 10.12301/spxb202200785

      Abstract (289) HTML (539) PDF 14.90 M (627) Comment (0) Favorites

      Abstract:Noni fruit is rich in bioactive components with strong antagonistic and antioxidant activities. This study was carried out to explore the difference of endophytic bacterial diversity in Hainan noni fruit and the connection between their key activities and diversity. The common dominant bacterial genera from 4 varieties of noni fruit (long fruit labeled L, round fruit labeled R, conjoined fruit labeled C, and Tahitian fruit labeled T) was identified by high-throughput sequencing technology as Brevundimonas, Pantoea and Bacillus. The antagonistic activity of endophytic bacteria was tested, then the total antioxidant activity of the endophytic bacteria with antagonistic activity was further determined. It was found that there was antioxidant activities among all the endophytic bacteria with antibacterial activity, and the antioxidant values were found to be in the range of 3.07-20.78U·mL-1, and the antioxidant activities of the endophytic bacteria were positively correlated with antagonistic activities. Eight endophytic strains from 4 varieties of noni fruit with strong activities were selected for 16S rDNA and gyrA molecular identification. The endophytic bacteria were identified as Bacillus and belonged to Bacillus subtilis, Bacillus mojavensis and Bacillus pumilus, respectively. The results of this study compared the diversity differences of endophytic bacteria communities in different varieties of noni fruit from the perspective of microbiology, and explored the correlation between the function of endophytic bacteria and endophytic community, confirming the theory of plant-microbial interactions. It was hoped that this study could provide help for the future research on the coordination and unity of endophytic bacteria and their host functions, provide a theoretical basis for the screening and application of endophytic bacteria with specific functions in noni fruit, and provide more ideas for the application of endophytic bacteria in the food industry and the research on the interaction between plants and microorganisms.

    • Identification and Carbon Metabolic Fingerprinting Analysis of Four Pathogenic Fungi Isolated from Ficus carica Linn.

      2023, 41(3):98-106. DOI: 10.12301/spxb202200019

      Abstract (371) HTML (505) PDF 8.25 M (528) Comment (0) Favorites

      Abstract:Ficus carica Linn., a tender and juicy fruit, is susceptible to be damage and infected by microorganisms. Pathogenic fungi were isolated from infected site of Ficus carica Linn. during post-harvest storage and studied by morphological observation, rDNA internal transcribed spacer (ITS) sequence analysis of fungi and phylogenetic tree construction. The isolated pathogenic fungi were reinoculated back to the healthy fruits, and their symptoms were the same as those of the infected fruits. Four filamentous pathogenic fungi were isolated from infected fruit and leaf as Alternaria alternata (179#), Fusarium odoratissimum (180#), Colletotrichum endophyticum (181#), and Mucor racemosus (182#), among which Fusarium odoratissimum , Colletotrichum endophyticum and Mucor racemosus were the first report of causing disease of Ficus carica Linn.. Biolog microbial identification system was used to analyse the carbon metabolic fingerprinting of four pathogenic fungi. The results showed that four strains had similar metabolic characteristics to 60 carbon sources, including 56 available carbon sources such as L-arabinose, D-cellobiose, α-cyclodextrin and ect., and 4 unavailable carbon sources such as N-acetyl-D-galactosamine, N-acetyl-β-D-mannosamine, L-trehalose and D-methyl lactate. This study provided a preliminary reference for biological features of pathogenic fungi and post-harvest control measures for Ficus carica Linn. diseases.

    • Effects of Lactobacillus and Saccharomyces cerevisiae Fermentation on Structure Characteristics and Antioxidant Properties of Gracilaria lemaneiforms Polysaccharide

      2023, 41(3):107-115, 147. DOI: 10.12301/spxb202200687

      Abstract (437) HTML (505) PDF 7.68 M (593) Comment (0) Favorites

      Abstract:The improvement effect of microbial fermentation on in vitro antioxidant properties of Gracilaria lemaneiforms slurry polysaccharide was studied to provide theoretical support for high value utilization of Gracilaria lemaneiforms. The structure changes of polysaccharide before and after fermentation by Lactobacillus RP38 and Saccharomyces cerevisiae JJ4 were analyzed by modern chromatography and spectral analysis techniques. The free radical scavenging ability of slurry polysaccharides before and after fermentation was investigated. The result showed that the mass fraction of polysaccharide increased from 0.30% to 0.79%, and sulfated polysaccharide mass fraction increased from 0.03% to 0.12%. Results of gel permeation chromatography and infrared spectroscopy revealed that functional groups of Gracilaria lemaneiforms polysaccharides remained unchanged after biological fermentation, the molecular weight of the polysaccharide was reduced, and then more sulfate groups exposed. In addition, it was found by nuclear magnetic resonance scanning that sulfate group of sulfated polysaccharide was mainly distributed in the C-6 position of galactose. The distribution position of sulfate was not changed by biological fermentation, but the content of sulfate was improved. The hydroxyl radical scavenging ability of Gracilaria lemaneiforms polysaccharide was increased by 5.33% and the superoxide radical scavenging ability was increased by 32.12% after fermentation. In conclusion, the antioxidant properties of Gracilaria lemaneiforms slurry could be improved by Lactobacillus RP38 and Saccharomyces cerevisiae JJ4, which may be related to the fact that the formation of small molecular polysaccharide with hydrogen supply capacity and more sulfate groups exposure during fermentation.

    • Antioxidant Activity and Structural Characteristics of Digestion Products of Longli 1 Quinoa Albumin in Vitro

      2023, 41(3):116-126. DOI: 10.12301/spxb202200852

      Abstract (385) HTML (480) PDF 10.38 M (581) Comment (0) Favorites

      Abstract:To study the antioxidant activity and its structural characteristics of albumin from Longli 1 quinoa seeds, quinoa albumin as raw material, the antioxidant activity and structural changes of quinoa albumin during in vitro simulated digestion were analyzed by Fourier transform infrared spectroscopy and scanning electron microscope. The results showed that the degree of hydrolysis of quinoa albumin and the release of free amino acids increased significantly with the digestion of pepsin and trypsin, reaching 39.60% and 45.46mg/L respectively at the end of simulated digestion. After simulated gastrointestinal digestion, DPPH· and ABTS+· scavenging rate, total reducing power, Fe2+ chelation rate and Cu2+ chelation rate of albumin digestion products were 58.43%, 79.51%, 0.280,66.84% and 15.74%, respectively, which were 34.85%, 68.62%, 0.179,54.52% and 7.76% higher than those of undigested albumin. In the whole process of simulated digestion, the content of β-angle increased significantly, while the content of α-helix and random coil decreased first and then increased with the passage of digestion time. The content of β-fold increased first and then decreased. Scanning electron microscope observation showed that after pepsin hydrolysis, the digested particles become significantly smaller and disorderly arranged in a dense structure. The surface area and the pore size of digested particles increased. The research results were aimed to provide a basis for the further utilization of quinoa albumin of Longli 1 quinoa seeds.

    • Effects of pH on Structure and Emulsibility of Catechin-Soy Protein Isolate Complex

      2023, 41(3):127-138. DOI: 10.12301/spxb202200988

      Abstract (749) HTML (502) PDF 14.07 M (597) Comment (0) Favorites

      Abstract:Soy protein isolate (SPI) was used as raw material to prepare protein complexes loaded with catechins under different pH conditions. The interaction mechanism was explained by analyzing thermal stability, fluorescence quenching type, binding site number, thermodynamic parameters, and secondary structure content by differential scanning calorimetry, ultraviolet-visible spectroscopy, fluorescence spectroscopy, and circular dichroism spectroscopy. The binding affinity between catechin and SPI, and the emulsibility of the complexes were analyzed. The results showed that fluorescence quenching type of catechin on SPI under different pH was static quenching. Electrostatic interaction was the main force between catechin and SPI when treated under pH 3.5,5.5 and 6.5. Additionally, hydrogen bonds and van der Waals forces were the mainly intermolecular forces for the complex under pH 4.5. Moreover, hydrophobic interactions played major roles in the interaction between catechin and SPI at pH 7.0,7.5,8.5 and 9.5. The thermal stability of the complex gradually increased with the increase of pH value. Furthermore, the SPI denaturation temperature of complex increased to 157.09℃ at pH 9.5. The emulsifying activity and emulsion stability of the complex at pH 7.5 were 7.70% and 13.44% which were significantly higher than those of the control group (SPI) under the same pH (P<0.05). The catechin-SPI complex structure could be changed under different pH treatments. Thus, soybean protein food base with good emulsibility could be prepared by regulating the pH value.

    • >Applied Technology
    • Modification of Corynebacterium glutamicum by Metabolic Engineering for Pyruvate Production

      2023, 41(3):139-147. DOI: 10.12301/spxb202200573

      Abstract (378) HTML (440) PDF 7.33 M (458) Comment (0) Favorites

      Abstract:Pyruvate is an essential organic acid which plays an important role in the energy metabolism of living organisms. As a precursor, pyruvate can be involved in the biosynthesis of many organic compounds. Therefore, metabolic engineering was used to modify Corynebacterium glutamicum for pyruvate production. Five key genes (pyruvate quinone oxidoreductase gene pqo, pyruvate carboxykinase gene pyc, aminotransferase gene alaT, valine-pyruvate aminotransferase gene avtA, pyruvate dehydrogenase gene aceE), related to pyruvate metabolic tributaries in Corynebacterium glutamicum, were successfully knocked out by homologous recombination. The concentration of pyruvate reached 14.64g/L after 72h of fermentation in shaking flasks. Then, transketolase gene tkt, transaldolase gene tal, and phosphoenolpyruvate carboxykinase gene pck were overexpressed to increase the supply of precursors for pyruvate synthesis. After 72h of fermentation in shake flasks, pyruvate production reached 15.39g/L, which was 28 times higher than that of the wild-type strain. This study aimed to provide theoretical reference for application of pyruvic acid production by microbial fermentation.

    • Flavor Characterizations of Maillard Reaction Products of Enzymatical Hydrolysates of Soybean and Chicken with Different Molecular Weights

      2023, 41(3):148-162. DOI: 10.12301/spxb202200174

      Abstract (1696) HTML (463) PDF 11.84 M (527) Comment (0) Favorites

      Abstract:In order to study the flavor characteristics of peptides with different molecular weights via Maillard reaction, the protein hydrolysates were obtained by enzymatic hydrolysis using soy protein and chicken as raw materials. Then the enzymatic hydrolysates were separated by ultrafiltration to obtain peptides with different molecular weights, less than 1000Da, 1000~5000Da and greater than 5000Da. In addition, the complex amino acids were obtained by complete acid hydrolysis of enzymatical hydrolysates of soybean and chicken. A certain amount of xylose was added in peptides and amino acids to build a Maillard reaction model. The sensory properties of Maillard reaction products were evaluated. Then the volatile and nonvolatile compounds were analyzed by gas chromatography-mass spectrometry and high-performance liquid chromatography. The results showed that in the Maillard product of enzymatical hydrolysates of two different protein sources, a total of 69 kinds of volatile compounds were identified, among which the contents of pyrazine, furanthiol and other meat flavor compounds were the highest. Statistical analysis showed that there were significant differences in volatile compounds of peptides with different molecular weights and free amino acids. The formation of pyrazine compounds was promoted by peptides less than 1000Da during the Maillard reaction, such as pyrazine, 5-methyl-2-ethylpyrazine, 2,5-methyl-3-ethylpyrazine, trimethylpyrazine, 2-acetylpyrrole, etc. Compared with peptides, free amino acids favored the formation of sulfur-containing compounds such as furanthiols and thiophenes. Only 29 volatile compounds had relative odorant activity values (rOAV) greater than 1. Partial least squares regression (PLSR) was used to investigate correlations between key odor compounds and sensory evaluations. Peptides less than 1000Da were found to be closely related to the basic meaty and kokumi, while peptides greater than 5000Da were closely related to bitter and burnt flavor. After Maillard reaction, the amount of peptides greater than 5000Da was significantly reduced. Degradation of peptides of 1000-5000Da could replenish the consumed free amino acids. The peptides less than 1000Da were prone to cross-link and polymerization and thus increased the content. The products had a significantly enhanced effect on the flavor, and could contribute well to the basic meaty, umami and kokumi. It was hoped that this study could provide theoretical support and guidance for the application of proteolysates to produce Maillard reaction products.

    • Study on Models of Phosphorus Adsorption in Whole Egg Liquid by Three Adsorbents

      2023, 41(3):163-174. DOI: 10.12301/spxb202200923

      Abstract (468) HTML (535) PDF 11.74 M (559) Comment (0) Favorites

      Abstract:Whole egg liquid is rich in protein, fat, and many kinds of vitamins and minerals. It is a natural source of nutritional supplements, but high level of phosphorus limits its use in the diet of patients with kidney disease. Activated carbon, hydrotalcite and diatomite were selected to dephosphorize the whole egg liquid. The dephosphorization rate, protein loss rate and color difference changes were taken as the indexes, the optimum amount of adsorbent, adsorption time and adsorption temperature were optimized, and then, the adsorption isotherms, adsorption kinetics and adsorption thermodynamics of phosphorus adsorption by three adsorbents in the whole egg liquid were fitted. The results showed that the optimum dosage of activated carbon was 8g/L, adsorption time was 120min and adsorption temperature was 35℃, while the optimum dosage of hydrotalcite was 8g/L, adsorption time was 150min and adsorption temperature was 35℃, and the optimum dosage of diatomite was 8g/L, the adsorption time was 90min and the adsorption temperature was 35℃. In the process of adsorption, hydrotalcite led to the least loss of protein and the highest adsorption specificity for phosphate groups. Activated carbon had the greatest effect on a*, diatomite had the greatest effect on b*, and all three adsorbents increased L*. The study of adsorption mechanism showed that diatomite was adsorbed in the form of monolayer, and n value of Freundlich adsorption isotherm of three adsorbents were all greater than 1. With the increase of adsorption temperature, the KF of activated carbon, hydrotalcite and diatomite increased gradually. The quasi-first-order kinetic model R2 of three adsorbents were lower, and fluctuated with the increase of temperature. The quasi-second-order kinetic model R2 of diatomite was higher, and the chemical adsorption degree of diatomite was higher. The ΔG of activated carbon, hydrotalcite and diatomite were all negative and the ΔH were greater than 0, which meant that the reaction was spontaneous and endothermic.

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