Passion fruit peel contained various phenolic compounds with alpha-glucosidase and alpha-amylase inhibitory activities in vitro. However, the bound state and glycosylated forms hindered their active expression. In this article, beta-glucosidase-producing Lactobacilli were inoculated into fermented peels for targeted metabolism. The results showed that the release of bound polyphenols and the increase of free polyphenols were significantly correlated with beta-glucosidase activity. The strain G1 with high enzyme activity degraded 48.20% of the bound polyphenols after 24 h. The ability of extracts to inhibit alpha-glucosidase and alpha-amylase activities was significantly enhanced and closely related to the content of free polyphenols (r = -0.96 and -0.88, P < 0.001). Computer-assisted screening identified 38 phenolic compounds as potential dual inhibitors of alpha-glucosidase and alpha-amylase. Among them, 22 alpha-glucosidase inhibitors and 24 alpha-amylase inhibitors were identified for the first time. Various inhibitors, including phenolic acids, flavones, and flavonols, increased in content after fermentation. The total content of 14 glycosylated polyphenols decreased to 28.38% at 48 h, which was opposite to the aglycone. Molecular docking indicated that glycosylated polyphenols bind to beta-glucosidase through hydrogen bonds and van der Waals forces. Different glycosylations at the C-3 position of quercetin bound at same sites to beta-glucosidase. This study contributes to the theory of enhancing the functional activity of natural products through targeted fermentation transformation.

In this study,theabrownin from Liupao tea was extracted and separated into extractable(FTB)and non-extractable(BTB)fractions using methanol.The composition of the two fractions was analyzed by Fourier transform infrared(FTIR)spectroscopy,sodium dodecyl-sulfate polyacrylamide gel electrophoresis(SDS-PAGE),Western blot,and ultra-high performance liquid chromatography-high resolution mass spectrometry(UPLC-HRMS).The study found that the theabrownin was a polyhydroxyl aromatic compound complexed with nitrogen compounds,including proteins,amino acids,and peptides.Electrophoresis showed two protein bands with molecular masses ranging from 63 to 75 kDa,which were generally diffuse long strip-shaped and may be modified by polyphenols and other substances.Non-targeted metabolomics identified 297 compounds.A total of 137 significantly differential compounds between FTB and BTB were selected using the cutoff of fold change(FC)>2 or FC<0.5 and P<0.05,the major ones being phenolics(37).Principal component analysis(PCA)and orthogonal partial least squares-discriminant analysis(OPLS-DA)revealed that catechin,2,3-dihydroxybenzoic acid,gallic acid,4-hydroxycoumarin,and caffeic acid could be used to discriminate between FTB and BTB and may be the major non-extractable phenolics of theabrownin.This study contributes to the understanding of protein-polyphenol complexes in dark tea and encourages further research of the composition and functional activity of theabrownin in dark tea.

This study sequentially extracted five cell wall polysaccharides from passion fruit peels using water, cyclohexane-trans-1,2-diamine tetra-acetate (CDTA), Na2CO3, and NaOH at varying concentrations. The composition, structure, and physical properties of these polysaccharides were investigated. The results demonstrated that water-extracted polysaccharides yielded the highest content, accounting for 9.04% of the dry weight of the peel's alcohol-insoluble residue. This was followed by polysaccharides extracted with 4 mol/L NaOH (8.15%), 0.05 mol/L CDTA (7.38%), 0.05 mol/L Na2CO3 (5.36%), and 1 mol/L NaOH (3.89%). Water-extracted and 0.05 mol/L CDTA-extracted polysaccharides were dominated by homogalacturonan, with molecular weights of 198.46 kDa and 73.67 kDa, respectively. The 0.05 mol/L Na2CO3-extracted polysaccharides had a high percentage of rhamnogalacturonan (53.47%) and the most negligible molecular weight (30.29 kDa). The polysaccharides extracted with 1 mol/L NaOH and 4 mol/L NaOH were hemicellulosic in nature, primarily composed of xylose, glucose, mannose, and galactose. All polysaccharides exhibited shear-thinning flow behaviors in aqueous solutions. The 0.05 mol/L Na2CO3-extracted polysaccharides showed the highest apparent viscosity and demonstrated elastic behavior, with the elastic modulus G′ exceeding the viscous modulus G″. The water-extracted polysaccharides and the 0.05 mol/L CDTA-extracted polysaccharides exhibited a gel-to-sol transition at angular frequencies near 1.10 and 0.43 rad/s, respectively. The 0.05 mol/L Na2CO3-extracted polysaccharides displayed relatively excellent emulsifying ability and emulsion stability. Hemicellulosic polysaccharides exhibited lower viscosity and higher thermal stability. Thus, passion fruit peels contained abundant cell wall polysaccharides, with different polysaccharides showing varied potential for emulsification and food texture improvement. This study provides valuable insights for the in-depth development of the extraction and use of peel polysaccharide fractions.

The increase of polysaccharides in the dark tea pile process is thought to be connected to the cell wall polysaccharides' breakdown. However, the relationship between tea polysaccharides (TPSs) and tea cell wall polysaccharides has not been further explored. In this study, the structural changes in the cell wall polysaccharides [e.g., cellulose, hemicellulose (HC), and pectin] in Liupao tea were characterized before and after traditional fermentation and tank fermentation. Additionally, the degradation mechanism of tea cell wall polysaccharides during fermentation was assessed. The results showed that cellulose crystallinity decreased by 11.9-49.6% after fermentation. The molar ratio of monosaccharides, such as arabinose, rhamnose, and glucose in HC, was significantly reduced, and the molecular weight decreased. The esterification degree and linearity of water-soluble pectin (WSP) were reduced. TPS content increases during pile fermentation, which may be due to HC degradation and the increase in WSP caused by cell wall structure damage. Microorganisms were shown to be closely associated with the degradation of cell wall polysaccharides during fermentation according to correlation analyses. Traditional fermentation had a greater effect on the cellulose structure, while tank fermentation had a more noticeable impact on HC and WSP.

BACKGROUNDPile fermentation is one of the key steps in developing the Liupao tea (LBT) quality and unique characteristics. The complex biochemical profile of LBT results from microorganisms present during the pile-fermentation process. However, the critical underlying microorganisms and the marker compounds still need to be determined.RESULTSStaphylococcus, Brevibacterium, Kocuria, Aspergillus, and Blastobotrys were the common dominant microorganisms at the end of the pile fermentation of LBT. Staphylococcus, Aspergillus, Blastobotrys, and nine other genera carried by raw tea are the core microorganisms in the LBT during pile fermentation. A total of 29 critical compounds contributed to the metabolic changes caused by the processing of LBT. Of these, gallic acid, adenine, hypoxanthine, uridine, betaine, 3,4-dihydroxybenzaldehyde, and alpha-linolenic acid could be characterized as potential marker compounds. Correlation analysis showed that the core microorganisms, including Sphingomonas, Staphylococcus, Kocuria, Aureobasidium, Blastobotrys, Debaryomyce, and Trichomonascus, were closely related to major chemical components and differential compounds. Moreover, the mutually promoting Staphylococcus, Kocuria, Blastobotrys, and Trichomonascus were correlated with the enrichment of marker compounds. Integrated molecular networking and metabolic pathways revealed relevant compounds and enzymes that possibly affect the enrichment of marker compounds.CONCLUSIONThis study analyzed the LBT fermentation samples by omics analysis to reveal the stable microbial community structure, critical microorganisms, and markers compounds affecting the quality of LBT, which contributes to a better understanding of pile fermentation of LBT and the fermentation theory of dark tea. (c) 2023 Society of Chemical Industry.

This study extracted and purified a natural polysaccharide (TPS-5) that has a molecular weight of 48.289 kDa from Liupao tea, a typical dark tea with many benefits to human health. TPS-5 was characterized as a pectin-type acidic polysaccharide. It has a backbone composed of → 2,4)- α- L-Rhap-(1) → 4)- α- D-GalAp-(1) →, with a branch composed of → 5)- α- L-Ara-(1 → 5,3)- α- L-Ara-(1 → 3)- β- D-Gal-(1 → 3,6)- β- D-Galp-(1) →. The in vitro biological activity evaluation illustrated that TPS-5 has free radical scavenging, ferric-ion-reducing, digestive enzyme inhibitory, and bile-salt-binding abilities. These results suggest that TPS-5 from Liupao tea has potential applications in functional foods or medicinal products.

文章旨在筛选具有体外降胆固醇能力的潜在益生菌.以实验室储藏的140株乳酸菌为基础,对比其降胆固醇能力、细胞黏附性、胃肠液耐受性及菌株安全性,并将具有优良降胆固醇能力(42.55％)的益生菌ST-Ⅲ为参照,最终筛选出一株具有良好益生活性的可降解胆固醇(40.43％)的植物乳杆菌HGP42.该菌株经热灭活后的降解能力为15.89％,表明菌株失活后仍可发挥一定的降胆固醇功效,溶血性与药敏实验均显示其安全可用.此外,HGP42的Caco-2细胞黏附能力(14.20％)、胃肠液环境存活率(大于80％)均高于ST-Ⅲ菌株.综上,植物乳杆菌HGP42具有作为商业益生菌乃至后生元的潜力.

目的 比较六堡茶成品茶和毛茶茶汤胶体性质与茶乳酪(沉淀)的成分组成差异.方法 通过动态光散射、扫描电子显微镜和高效液相色谱法等方法比较了六堡茶毛茶以及发酵后的成品茶茶汤的胶体颗粒及沉淀性质.结果 六堡茶毛茶和成品茶茶汤中均存在胶体体系.两种茶汤冷却过程的浊度增加率逐渐减少,接近常温(25℃)时,成品茶茶汤浊度增加率小于毛茶;两种茶汤中存在球形或椭球形的胶体颗粒,且胶粒粒径与 Zeta电位具有温度响应.25℃下成品茶茶汤的胶体颗粒平均粒径(2131.0 nm±144.2 nm)低于毛茶(3045.8 nm±67.9 nm),成品茶茶汤Zeta电位(?24.8 mV±0.8 mV)高于毛茶(?19.2 mV±0.2 mV).两种茶汤成分差异导致二者沉淀差异,成品茶固形物相对沉淀率(2.22%)小于毛茶(2.79%),成品茶沉淀主要成分为茶红素、蛋白质和多糖,占沉淀总量 58.83%,毛茶则为多酚、蛋白质和多糖,占沉淀总量 75.76%,两种茶汤沉淀中酯型儿茶素总量均高于非酯型儿茶素总量,其酯型儿茶素、蛋白质、多糖和黄酮较易参与沉淀形成.结论 发酵使成品六堡茶的茶汤的胶体颗粒稳定性增加,使其形成的茶乳酪与发酵前存在明显差异.本研究为黑茶饮料等食品的开发提供了理论基础.

目的 对比两种同时检测茶叶中赭曲霉毒素A(ochratoxin A,OTA)与桔霉素(citrinin,CIT)的方法.方法 考察不同提取方法、溶剂、料液比的提取效果,比较适配体结合超滤法与免疫亲和柱纯化效果;对比高效液相色谱-荧光检测器(high performance liquid chromatography-fluorescence detector,HPLC-FLD)与超高效液相色谱-三重四极杆质谱法(ultra performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)测定OTA与CIT的检出限、精密度、准确度等差异,评价方法的适用性.结果 采用70%甲醇超声与振荡的提取方法,在料液比为 1:3 的条件下,OTA、CIT的提取率最佳,回收率分别为 99.49%的 92.77%;经适配体结合超滤纯化后,CIT与OTA的回收率为82.07%～92.95%,与免疫亲和柱纯化方法效果类似;UPLC-MS/MS测定CIT和OTA的基质效应(20.0%、-20.0%)小于HPLC-FLD测定CIT和OTA的基质效应(48.8%、50.3%),二者测定CIT与OTA均具有良好线性度,相关性系数均不小于 0.9989;HPLC-FLD测定CIT与OTA的检出限分别为 0.09 μg/kg、0.12 μg/kg;UPLC-MS/MS测定CIT和OTA的检出限分别为0.12 μg/kg、0.09 μg/kg,两种方法的加标回收率分别为 84.20%～100.70%与 89.22%～97.88%,相对标准偏差分别为 1.30%～4.31%与 0.74%～4.04%.结论 适配体结合超滤纯化方法操作简单,成本低廉,免疫亲和柱纯化方法成本较高且低浓度下的准确度高;HPLC-FLD 和UPLC-MS/MS均适用于茶叶基质中CIT与OTA的提取与检测,但后者基质效应更低,定性更准确.

In order to determine the regulatory function of Liupao tea polysaccharide on intestinal tract, hyperlipidemia rats were intragastric administrated with Liupao tea polysaccharide of 100, 300 and 500 mg/kg·bw for 4 weeks. The results showed that the mass of colon contents, propionic acid, butyric acid and total short chain fatty acid content of rats in the middle and high dose group of Liupao tea polysaccharide were significantly increased. The high-throughput Illumina Hiseq sequencing results, species differences and correlation analysis showed that Liupao tea polysaccharide can significantly reduce the ratio of firmicutes to bacteroidetes, increase the abundance of beneficial bacteria such as prevotella,ruminococcus, bacteroidetes, alloprevotella, blautia, lactobacillus and other beneficial bacteria in rat intestinal flora, and decrease the abundance of lachnospiraceae, turicibacter, eubacterium and other genera, among them,the increase of abundance of rumococcus and blautia is positively correlated with the improvement of blood lipid level in rats. It shows that Liupao tea polysaccharide can regulate blood lipids by up-regulating the abundance of beneficial bacteria, improving the structure of intestinal flora in rats, and promoting the content of short-chain fatty acids in the colon.

银耳多糖作为一种具有益生元潜力的多糖,其在发挥作用前必需经过体内的消化与吸收.该研究通过探讨银耳多糖体外模拟消化过程中的物质组成与理化性质的变化来研究其在口腔、胃和肠三个阶段的消化特性.研究表明,三个消化阶段结束后,除质量分数0.5％样品略有增加外,不同浓度的多糖样品中的还原糖含量均未产生显著变化;银耳多糖主要由甘露糖、葡萄糖、半乳糖醛酸、半乳糖、葡萄糖醛酸组成,且在整个消化过程中,均未被消化酶分解而产生新的游离单糖;不同浓度银耳多糖经胃液消化后,低pH值的胃消化环境会引起多糖分子量的降解,其中0.5％浓度样品组在经三个阶段消化后逐渐较低到3.91×103、3.52×103与2.92×103 ku.消化过程中多糖的结构与组成变化主要取决于pH值的变化,与消化液中的消化酶关系不大,其中适宜浓度的多糖溶液可在消化过程中由于其粘度特性而保持更稳定的结构性质.

桂林腐乳酸浆水是桂林腐乳制作过程中的凝固剂,其富含的微生物赋予了腐乳特有的品质.而桂林腐乳酸浆水中乳酸菌的种类及其具有的优良功能活性尚不清晰.该研究从酸浆水中筛选出10株乳酸菌,其中5株具有产β-葡萄糖苷酶能力.经生理生化和16SrRNA鉴定,a1、a3、a7和b16为利莫西发酵乳杆菌(Limosilactobacillus fermentum),b8为德氏乳杆菌(Lactobacillus delbrueckii).b8展现出最高的β-葡萄糖苷酶活力(发酵6h时为(41.22±0.47)U/105CFU),生长活力和产酸能力也显著高于其余4株产酶乳酸菌(P<0.05).此外,德氏乳杆菌b8在培养12h时的DPPH、ABTS自由基清除率分别为(16.29±2.22)％、(51.02±2.43)％.综上,德氏乳杆菌b8具有较好的功能活性和生长活力,该研究既丰富了对桂林腐乳酸浆水中乳酸菌的认识,又为豆制品行业提供了潜在的功能性发酵菌株.

Purple passion fruit peels are rich in polyphenols and glycoside bound flavonoids. Lactic acid bacteria（LAB） fermentation has proven to release bound polyphenols, but whether LAB fermentation by β-glucosidase producing bacteria is more conducive to release remains unproven. Two strains of β-glucosidase producing and one strain of non β-glycosidase producing were used to ferment passion fruit peel separately. The results showed that the total polyphenols content of passion fruit peel increased after fermentation, and the capacity of two β-glycosidase producing bacteria to release free polyphenols was 1.31 and 1.06 times higher than that of the non β-glycosidase producing bacteria. And this metabolic capacity was closely related to the enzyme activity. The antioxidation and digestive enzyme inhibition were significantly improved（P＜0.05）, and passion fruit peel fermented by β-glucosidase producing LAB exhibited significantly stronger digestive enzymes inhibition than the non β-glycosidase producing LAB. These results indicate that fermentation with β-glucosidase producing LAB is more conducive to the conversion of bound polyphenols to free polyphenols in passion fruit peels and increase the total polyphenols content, thus having a promising application in enhancing polyphenols bioactivity.

Tank fermentation is a novel approach to fermenting teas; however, the species of microorganisms present remain unclear. The microbial community composition of Liupao tea at various stages of tank fermentation was analyzed using high-throughput sequencing. Sphingomonas, Aquabacterium, Pelomonas, Acinetobacter, Blastobotrys, Aspergillus, Debaryomyces, and Aureobasidium were the predominant genera, which is different from pile fermentation. Fifteen genera (including Lactobacillus, Debaryomyces, Candida, Allobaculum, Flavobacterium, Caulobacter, Blastobotrys, Aspergillus, and Rasamsonia) were identified as biomarkers. PICRUSt analysis predicted that the most abundant functional genes were related to metabolism of carbohydrates, amino acids, cofactors, vitamins, and other secondary metabolites. Using the pure culture method, 283 strains were isolated at various stages of fermentation, representing 20 genera and 29 species of bacteria, and 11 genera and 18 species of fungi. Most of the dominant Sphingomonas, Staphylococcus, Aspergillus, and Blastobotrys identified by sequencing were also isolated. Of these, Sphingomonas olei, Aspergillus luchuensis, Aspergillus niger, Aspergillus aculeatus, Aspergillus amstelodami, Blastobotrys adeninivorans, Candida metapsilosis, and Candida blankii were beneficial strains that might be used to ferment Liupao tea. This study provides a basis for the development of processing technologies and utilization of microbial strains in the production of dark teas. PRACTICAL APPLICATION: Microbial diversity in tank-fermented Liupao tea was reported for the first time. 8 microorganisms were the predominant genera. The species, functions and potential risks of microorganisms was revealed. We clarified the differences between tank and pile fermentation.

Polyphenols and isoflavones are the main bioactive components of soybean. During traditional processing, many active compounds are lost because of filtration and discard of okara. However, reports on changes in phenolic compounds, especially bound phenolic compounds (BPC), during the fermentation of whole soybean milk (WSM) are few. In this paper, three lactic acid bacterias (LABs) with different 8-glucosidase activities were used to evaluate the effect of 8-glucosidase and different okara contents in soybean milk on the conversion of extractable and non-extractable polyphenols during fermentation. The results showed that the action of 8-glucosidase improved the release of BPC and isoflavones. During WSM fermentation, the 8-glucosidase-producing capacity of LABs strongly correlated with both the decrease in conjugated phenolic compounds and isoflavone glycosides, and the increase in free phenolic compounds and isoflavone aglycones. With the increase of okara content, the acid tolerance of Lactobacillus delbrueckii b8 was enhanced and the viability increased. During L. delbrueckii b8- mediated fermentation, the 8-glucosidase activity of soy milk with high okara content (59.07 +/- 1.48 U/mL) was 1.62 times that of soy milk with low okara content (36.43 +/- 1.38 U/mL). As the okara concentration increased, the release of soybean polyphenols increased. Moreover, high okara content and high 8-glucosidase activity mutually promote polyphenol conversion in soy yogurt. Therefore, WSM fermentation by 8-glucosidase-pro-ducing LAB is a method for increasing the phenolic compound content in soymilk. This approach can offer a theoretical guide for efficiently utilizing soybean polyphenols and developing phenolic compound-rich soymilk.

Liupao tea is a dark tea with unique quality. Semi-finished Liupao tea with two different fermentation processes (traditional/tank) was analyzed to explain the chemical characteristics and taste quality. The content change rate of polyphenols, flavonoids, and theabrownin in traditional fermentation was approximately twice that in tank fermentation. Electronic tongue revealed that bitterness and astringency increased, whereas aftertasteastringency decreased after fermentation. 36 compounds were identified as the biomarkers responsible for the metabolic changes caused by fermentation with significant decrements in catechins, catechin gallate, and alpha, alpha-trehalose, and significant increments in gallic acid content (VIP > 3; P < 0.05). In addition, 26 metabolites were identified to distinguish between tank and traditional fermentation, with correlation analysis indicating that catechin gallate, epicatechin and gallic acid accounting for the differences in taste between the two processes. This study provides a comprehensive insight into the chemical composition and sensory quality of different Liupao tea fermentations.

BACKGROUND: The targeted biological activity of a natural product is often the result of the combined action of multiple functional components. Screening for predominant contributing components of targeting activity is crucial for quality evaluation. RESULTS: Thirteen and nine phenolic compounds inhibiting alpha-glucosidase and alpha-amylase, respectively, were identified in the ethanol extracts of passion fruit peel through liquid chromatography-tandem mass spectrometry and multivariate analysis. Considering the different concentrations of components and their interactions, the role of the semi-inhibitory concentration (IC50) in the dose-effect relationship is limited. We proposed the active contribution rate (ACR), which is the ratio of a single component concentration to its IC50 in the whole, to assess the relative activity of each compound. Luteolin, quercetin, and vitexin exhibited a minimum IC50. Before the simulation of gastrointestinal digestion, quercetin, salicylic acid, and luteolin were identified as the dominant contributors to alpha-glucosidase inhibition according to ACR, while salicylic acid, 2,3-dihydroxybenzoic acid, and quercetin were identified as dominant contributors to alpha-amylase inhibition. After simulated digestion, the contents of all polyphenolic compounds decreased by various degrees. Salicylic acid, gentisic acid, and vitexin became the dominant inhibitors of alpha-glucosidase based on ACR (cumulative 57.96%), while salicylic acid and 2,3-dihydroxybenzoic acid became the dominant inhibitors of alpha-amylase (cumulative 84.50%). CONCLUSION: Therefore, the ACR evaluation strategy can provide a quantitative reference for screening the predominant contributor components of a specific activity in complex systems. (C) 2022 Society of Chemical Industry.

Summary Baking treatment is commonly used to improve the aroma and taste of tea but its effects on Liupao tea are unknown. The quality, nonvolatile and volatile compounds of the stale‐aroma type Liupao tea (CX) and its baked tea (HB) were investigated. After baking, the bitterness and aftertaste‐bitterness of the tea infusion were reduced, the aroma of grass was increased, and the stale was weakened. Caffeine, (−)‐epigallocatechin, (−)‐epigallocatechin gallate, (−)‐epicatechin gallate, and gallic acid content decreased significantly. Significant lipid content down‐regulation was observed in the differential metabolites, but phosphatidylcholines accumulated after baking. According to GC–MS, the reduction of methoxy compound content after baking was critical in the reduction of CX stale aroma. HB newly generated 2,4‐decadienal and (E, E)‐2,4‐heptadienal, which may be related to linoleic and linolenic acid lipid oxidation. This study contributes to a better understanding of Liupao tea and the impact of baking treatment on improving Liupao tea quality.

Consumption and emission reduction has become an inevitable trend in the development the food processing industry. While liquid-state osmotic pretreatment can save energy effectively in freeze-dried fruit processing, there is still a need to explore the effect of solid-state osmotic pretreatment. The effects of solid- and liquid-state osmotic pretreatment on waste liquid, resource consumption and product quality in the processing of freeze-dried mango were compared in this study. Results showed that compared with liquid-state infiltration (sucrose concentration of 60%, and solid-to-liquid ratio of 1:1; designated as L60), solid-state infiltration with sucrose concentration of 30% and 40% (designated as S30 and S40, respectively) significantly reduced the waste liquid discharge by 61.00% and 51.71%, the consumption of sucrose by 50.01% and 33.24%, and the total chemical oxygen demand of waste liquid by 60.13% and 41.83%, respectively. Compared with non-osmosed samples, the carbon emission of S30, S40 and L60 during processing was reduced by 10.59%, 12.21% and 8.80%, respectively. Compared with the liquid-state osmosis group, the solid-state osmosis group had lower nutrient retention (total phenolics and VC) during osmosis, but higher nutrient retention during lyophilization. After freeze-drying, the structure of the solid-state osmosis group was shrunk without collapse. In the trend of sustainable development, solid-state osmosis is superior to liquid-state osmosis in energy conservation and emission reduction, which is worthy of further research and exploration.