龙眼果肉发酵红茶菌饮料

以龙眼果肉和茶糖水为原料,探讨了发酵温度、初始可溶性固形物和接种量等因素对龙眼果肉红茶菌发酵的影响,并以总酸、D-葡糖糖二酸1,4-内酯和D-葡萄糖二酸为响应值,利用响应面设计进行工艺优化,得出佳的发酵条件为:温度29.6℃,初始TSS为14.7°Brix,接种量为14.1%,发酵时间6 d,所得发酵液总酸含量为26.87 g/L,D-葡糖糖二酸1,4-内酯为5.51 g/L,D-葡萄糖二酸为18.01 g/L。     

红茶菌A4发酵功能饮料的研制

以红茶茶汤(质量分数0.5%)、蜂蜜(质量浓度6.54%)作为发酵底物,接种本课题组前期分离纯化,并拥有知识产权的红茶菌葡糖酸醋酸杆菌(Gluconacetobacter sp.,A4)10%进行发酵,而研发出一款新的功能性饮料。这株菌代谢产出具有保肝护肝功效的功能因子D-葡萄糖二酸-1,4-内酯(D-Saccharic acid 1,4-lactone monohydrate,DSL)。静置于30℃环境下4~5 d得到发酵液,再将发酵液经离心、抽滤、调配、罐装、密封、杀菌等一系列工序,制成有功能性和独特风味的、可以进行工业生产的饮料。经过感官评价确定最终饮料配方为:87.35%发酵原液,12.24%白砂糖,0.16%柠檬酸,0.25%苹果酸。最终通过抗氧化能力的测定,与市售红茶菌发酵饮料进行比较,评定本产品的抗氧化性最佳。     

4种特色红茶菌发酵液感官品质、理化特性及菌群结构比较研究

目的 揭示不同红茶菌发酵液品质差异的内在原因。方法 以4种特色的红茶菌发酵液为研究对象(标记为A、B、C、D), 比较分析其在感官品质、理化特性和群落结构的差异。结果 4种红茶菌发酵液的香味、滋味差异较大, 色泽差异较小, 其中B在发酵第2 d具有独特发酵风味与茶香, 色泽橙黄, 口感清爽, 综合评分最高, 为74.2分; 4种红茶菌发酵液的菌体浓度、pH、总糖、乙酸、D-葡萄糖二酸-1,4-内酯(D-saccharic acid-1,4-lactone, DSL)及葡萄糖酸变化趋势相似, 但含量差异较大; 宏基因组测序及相关性分析表明, 4种红茶菌的优势真菌为Starmerella(暂无中文名称)和酒香酵母属(Brettanomyces), 优势细菌为驹形杆菌属(Komagataeibacter)和葡糖杆菌属(Gluconobacter), 其中Starmerella相比Brettanomyces更有利于乙酸生成, Gluconobacter相比Komagataeibacter利用碳源更高效。结论 4种红茶菌的菌群结构不同, 影响其对碳源的利用率和有机酸的形成,进而导致其发酵液感官品质上的差异。     

红茶菌主要功能菌株发酵糖茶水条件的研究

葡糖酸醋酸杆菌(Gluconacetobacter sp.A4)作为红茶菌中的主要功能菌株具有很强的产D-葡萄糖二酸1,4内酯(DSL)能力.本实验探讨了温度、pH、叶酸、木糖醇和发酵时间对A4生长及代谢产DSL的影响,得出最佳培养工艺:培养液组成为红茶0.5%(W/V)、葡萄糖5%(W/V)和木糖醇3%(W/V),接种量10%(V/V):在发酵过程中维持pH为4.0、发酵温度30℃,静止培养8d.发酵结束后,葡萄糖利用率达82%,DSL产量为4.69mg/ml.     

营养成分对红茶菌液中D-葡萄糖二酸-1，4-内酯和总酸含量的影响

采用纯化的酵母菌和木醋酸菌菌株培养红茶菌液,利用高效毛细管电泳法(HPCE)测定培养液中D-葡萄糖二酸-1,4-内酯(DSL)的含量,考察不同配方对DSL产量的影响。用HPCE法在培养10 d的红茶菌液中稳定检测到DSL;采用麦芽糖与绿茶培养的红茶菌液中的DSL含量达1.09 g/L,远高于乌龙茶和蔗糖培养液中的0.28 g/L。发现有利于DSL合成的糖类依序是:麦芽糖>葡萄糖>蔗糖;茶叶依序是:红茶≥绿茶>乌龙茶;较高浓度的糖不利于DSL的合成。测定发酵液中还原糖、总酸的含量,计算得率(酸/糖耗),发现葡萄糖和麦芽糖、绿茶和红茶有利于红茶菌液的成熟,高浓度的糖抑制红茶菌液的成熟。DSL浓度约占总酸的6.5%～7.3%,与总酸显著相关(α=0.01)。     

红茶菌菌种主要代谢产物的试验研究

本文介绍了红茶菌中几种主要代谢产物的生成特性,不同菌种及其不同组合所产生的代谢产物的种类和数量都各不相同。结果表明,菌种A22具有很强的代谢葡萄糖生成酸的能力,它可以产生大量的D-葡萄糖二酸1,4内酯,它是红茶菌中的主要功能因子,另外,A22还可产生较多的其它有益成分,如葡萄糖酸、葡萄糖醛酸和葡萄糖二酸等,而乙酸的含量适中。因此,该菌种是生产具有解毒、抗癌作用的红茶菌功能性饮料的理想菌种。     

HPLC法检测红茶菌中葡萄糖代谢曲线及培养基的优化研究

本实验室从红茶菌中分离出可以产生高含量的功能因子-葡萄糖二酸1,4内酯的菌株--葡糖酸醋酸杆菌(Gluconacetobactersp.A22)。本文利用高效液相色谱法检测葡萄糖,通过对葡萄糖代谢曲线的测定,确定了发酵时间为126h(30℃,160r/min振荡培养)。发酵结束时,残糖量与初始葡萄糖浓度呈线性关系:y=40.254x-35.862(R2=0.9999)。对A22培养基的优化进行了研究,结果表明,葡萄糖浓度5%(w/v)、茶叶浓度0.5%(w/v)时最适合A22发酵生产功能性饮料。     

国内外红茶菌研究进展

红茶菌是用含糖茶水通过接种醋酸菌和酵母,进行发酵生产的一种广受欢迎的健康饮料。近年来,国内外对红茶菌的研究主要集中在其制作工艺优化方面,小部分研究着重在红茶菌发酵动力学模型、抗氧化与抑菌活性的分子作用机理等方面,同时,国外还对红茶菌中的功能因子——葡萄糖二酸-1,4-内酯(D-Saccharic acid 1,4-lactone,DSL)对肝脏等器官的保护作用进行了研究;并且对红茶菌的一种副产物——细菌纤维也进行了深入研究,特别是在细菌纤维的纳米化等方面。本文主要从红茶菌的菌种组成、相关工艺进展和益生功效方面进行阐述,对比国内外红茶菌的研究进展,同时提出一些个人的见解。     

高效液相色谱法测定红茶菌中的功能因子

建立了一种利用高效液相色谱法同时分析红茶菌中2种主要功能因子(D-葡萄糖二酸1,4内酯和D-葡萄糖二酸)的方法。采用AgilentSB-Aq色谱柱(4.6mm×250mm,5μm),色谱条件:流动相为0.025mol/LKH2PO4(pH2.5),流速0.5mL/min,柱温30℃,进样量10μL,紫外检测波长为210nm。在此检测条件下,红茶菌中的2种主要功能因子能够得到较好分离,回收率为99.7%～102.3%,RSD<3%,精密度较高,重现性较好。     

红茶菌发酵工艺优化及菌液主要成分变化分析

对红茶菌发酵工艺进行了优化,以发酵液pH值和感官评分为衡量指标,得到红茶菌发酵最佳工艺条件为茶叶浓度0.6g/100mL、酵母菌接种量3%、蔗糖浓度8%,此时,红茶菌发酵液pH值为3.23,感官评分为92分,红茶菌饮料呈淡黄色,口味酸甜适中。对不同发酵条件下红茶菌发酵液主要成分进行了分析,结果表明蔗糖较适合于红茶菌发酵饮料的制作,发酵液蛋白质和多酚含量相对较高;相对于乌龙茶和黑茶,绿茶和红茶也较适合于红茶菌发酵饮料的制作;红茶菌发酵主要在前4d完成,发酵期间,多酚含量、糖度和pH明显下降,而酸度、蛋白质含量和酵母菌数量则明显增加,在发酵的后期阶段,主要成分的变化不明显。     

5种莲副产物中活性成分及其抗氧化、α-葡萄糖苷酶抑制活性比较

每年大量的莲叶、莲蓬壳、莲壳和莲衣因被丢弃而没有得到有效利用,因此,本研究旨在通过比较莲叶、 莲蓬壳、莲壳、莲衣和莲心提取物中主要活性成分的含量及其抗氧化和α-葡萄糖苷酶活性抑制能力,探讨其高值化 利用潜力。结果表明：莲蓬壳提取物中的总酚含量（232.50 mg GAE/g）和总三萜含量（423.75 mg OAE/g）最高, 而莲叶和莲衣提取物分别具有最高的总黄酮含量（41.48 mg QuE/g）和总缩合单宁含量（36.13 mg CaE/g）。同 时,莲蓬壳提取物具有最高的抗氧化和α-葡萄糖苷酶活性抑制能力,其1,1-二苯基-2-苦基肼自由基、2,2’-联氮基-双 （3-乙基苯并噻唑啉-6-磺酸）自由基清除能力和α-葡萄糖苷酶活性抑制能力分别为阳性对照的2.64、1.17、85 倍。 莲衣的抗氧化能力次之,莲叶、莲蓬壳、莲壳和莲衣的α-葡萄糖苷酶活性抑制能力均高于阿卡波糖。相关性分析显 示,多酚类和缩合单宁类化合物为莲副产物中主要的自由基清除剂和α-葡萄糖苷酶抑制剂,而黄酮类化合物对铁离 子还原能力的贡献最大。因此,莲蓬壳具有很好的抗氧化和抑制α-葡萄糖苷酶活性的能力,多酚、黄酮和缩合单宁 为其主要活性成分,具有进一步研究其体内降血糖、抗糖尿病及其并发症的价值。     

茶多酚对α-淀粉酶的抑制作用及分子机理

探究茶多酚对α-淀粉酶的抑制特性并分析其分子作用机制。采用抑制动力学的方法评价茶多酚对α-淀粉酶的抑制作用;通过荧光色谱法及圆二色谱法观察茶多酚对α-淀粉酶空间结构和稳定性的影响;利用分子对接技术,探究茶多酚与α-淀粉酶之间的分子相互作用。结果表明,茶多酚对于α-淀粉酶的活性具有明显的抑制作用,竞争类型为非竞争性抑制,半抑制浓度为1.35 mg/mL;茶多酚对α-淀粉酶具有荧光猝灭效应,其最大发射波长（λ_max）出现红移,α-淀粉酶的二级结构由层状结构向螺旋结构转变,其稳定性显著降低;茶多酚通过氢键、疏水相互作用等与α-淀粉酶形成稳定复合物,从而降低了酶的催化活性。研究结果表明,茶多酚具有作为α-淀粉酶抑制剂的潜在价值。     

Effects of tea polyphenols on the activities of α-amylase,pepsin, trypsin and lipase

Tea polyphenols (TP) possess many beneficial properties, such as reducing the risk of cancer and heart diseases, and acting as natural antioxidants for the food industry. At the same time, tea polyphenols might inhibit digestive enzymes and reduce food digestibility. To explore this possible antinutritional property, the effects of tea polyphenols on the activity of four typical digestive enzymes were investigated. HPLC analysis of the tea polyphenols extracted from Chinese green tea indicated that their catechin content was 93.6% (w/w), and that the content of ester bond-containing polyphenols was more than 82%. Measurement of the interaction of gelatin with tea polyphenols was first carried out, in order to model enzyme protein–TP interaction. It proved that tea polyphenols were capable of binding and precipitating protein, suggesting a potential ability of TP to denature digestive enzymes. In addition, the inhibitory effects of tea polyphenols on α-amylase, pepsin, trypsin and lipase were studied. In the presence of 0.05 mg/ml tea polyphenols, the inhibition ratios of α-amylase, pepsin, trypsin and lipase were, respectively, 61%, 32%, 38% and 54%, suggesting that TP might possess antinutritional properties.     

黑曲霉发酵牛蒡根的化学成分及对α-葡萄糖苷酶和α-淀粉酶抑制作用

为明确黑曲霉(Aspergillus niger)发酵对牛蒡(Arctium lappa)根的化学成分及其降糖活性的影响,本文采用黑曲霉发酵牛蒡根,分析不同发酵时间不同的发酵品对α-葡萄糖苷酶和α-淀粉酶抑制作用和化学成分的变化.酶抑制实验结果表明,牛蒡根对α-葡萄糖苷酶和α-淀粉酶的抑制作用随发酵时间延长而增强,牛蒡...     

Inhibition of the in vitro activities of α-amylase, α-glucosidase and pancreatic lipase by yellow field pea (Pisum sativum L.) protein hydrolysates

The aim of this work was to produce yellow field pea protein-derived peptides as inhibitors of α-amylase, α-glucosidase and pancreatic lipase activities. A pea protein concentrate was hydrolysed with alcalase, chymotrypsin, pepsin or trypsin and the hydrolysates separated into different fractions (<1, 1–3, 3–5, 5–10 kDa) by membrane ultrafiltration. Peptide sequence analysis showed that the alcalase hydrolysate had higher levels of di- and tripeptides when compared with the chymotrypsin, pepsin and trypsin hydrolysates. The peptide fractions inhibited α-amylase and α-glucosidase activities at levels that were similar to the unfractionated hydrolysates. The peptides were more active against α-amylase (inhibition at μg level) than α-glucosidase (mg level). In contrast, the fractionated peptides had reduced ability (IC₅₀ >4.2 mg mL⁻¹) when compared with the unfractionated hydrolysate (IC₅₀ <4.2 mg mL⁻¹) to inhibit lipase activity. Enzyme kinetic studies revealed that the peptides reduced α-amylase activity through competitive inhibition. However, inhibition of α-glucosidase activity was non-competitive.     

不同菌发酵紫薯制品对降血糖相关酶的影响及活性成分分析

以抑制降血糖相关的α-淀粉酶和α-葡萄糖苷酶活性为指标,以植物乳杆菌、保加利亚乳杆菌亚种、嗜热链球菌、低糖面包酵母、白酒酵母、葡萄酒酵母的单菌或其混合菌为发酵剂,分别对比以紫薯泥或紫薯汁为底物进行无氧或有氧发酵的发酵紫薯制品的抑制效果,并分析制品中的多糖、多酚、黄酮含量的变化。结果表明:发酵可提高制品对α-淀粉酶、α-葡萄糖苷酶的活性抑制效果,单一菌优于混合菌发酵制品,紫薯汁优于紫薯泥发酵制品。同时,发酵紫薯制品中非淀粉多糖、总酚、总酮含量对比未发酵紫薯均有提高。而其中以紫薯汁为底物,以低糖面包酵母为发酵剂的发酵紫薯制品对降血糖相关酶的活性抑制率最高,对α-淀粉酶的活性抑制率达到63.5%,对α-葡萄糖苷酶的活性抑制率达到70.9%,制品中的非淀粉多糖含量为3.52%,总酚含量为10.68 mg/10 g,总酮含量为0.78 mg/10 g。     

高粱原花青素对α-淀粉酶和蛋白酶活力影响的DSC研究

为了探讨高粱原花青素(SPC)对α-淀粉酶和蛋白酶活力的影响,采用差示扫描量热法(Differential Scanning Calorimetry简称:DSC)研究了SPC与这2种酶的相互作用。结果显示,不同浓度的SPC分别与α-淀粉酶和蛋白酶相互混合后,导致2种酶的相变温度和热焓都发生变化。表明SPC与2种酶都发生了相互作用,并影响了其活力。     

红茶菌酒的研制

该研究采用红茶菌和葡萄酒酵母发酵红茶糖水,制备红茶菌酒。通过单因素试验和正交试验对红茶菌酒的发酵条件进行优化,得到其最优发酵条件为：红茶糖水糖度16 °Bx,红茶菌发酵时间48 h,葡萄酒酵母接种量20%,红茶菌液pH值4.5,葡萄酒酵母的发酵温度30 ℃和发酵时间8 d。     

Hypocholesterolaemic and antioxidant effects of kombucha tea in high‐cholesterol fed mice

BACKGROUND: Traditional kombucha tea (TKT) is produced by mixed tea fungus. We previously proposed Gluconacetobacter sp. A4 as the key functional strain in kombucha culture, because it had strong ability to produce D ‐saccharic acid‐1,4‐lactone (DSL, a crucial functional component in KT). This study investigated the hypocholesterolaemic and antioxidant activities of TKT and modified KT (MKT, tea broth fermented by single Gluconacetobacter sp. A4). RESULTS: In vitro, TKT and MKT, but not DSL equally increased the radical scavenging effects and inhibited low density lipoprotein (LDL) oxidation. In vivo, the total cholesterol and LDL‐cholesterol (LDL‐C) lowering effects were not different between MKT and TKT. Compared with TKT, MKT showed a significantly elevated effect on the increase of antioxidantive enzymes activities (total antioxidant capacity and superoxide dismutase) and the decrease of malondialdehyde. Meanwhile DSL demonstrated an enhanced activity in lipid profile and antioxidant activities. CONCLUSION: KT had the hypocholesterolaemic and antioxidant effects. These effects were largely attributed to DSL. MKT was similar to or even more powerful than TKT in antioxidant and hypocholesterolaemic effects. Thus, Gluconacetobacter sp. A4 was further established as the main functional microorganism in kombucha culture. Moreover, KT may be useful in treating obesity. Copyright © 2008 Society of Chemical Industry     

Inhibitory activities of extracts from Cleistocalyx operculatus flower buds on pancreatic lipase and α-amylase

In this work, we investigated the inhibitory activities of aqueous extract (Eaq), 30, 60, and 95?% ethanol extracts (E₃et, E₆et, and E₉et), petroleum ether extract (Epe), ethyl acetate extract (Eae), and 2′,4′-dihydroxy-6′-methoxy-3′,5′-dimethylchalcone (DMC) from Cleistocalyx operculatus flower buds on pancreatic lipase and α-amylase, which were closely related to body weight and obesity. The inhibition effect of various extracts was determined by the Lineweaver–Burk plots. The results showed that the IC₅₀ values of DMC, Epe, Eae, and E₉et against pancreatic lipase were 101.5?μM, 38.65, 76.62, and 109.76?μg/ml, respectively, which were much lower than that of E₃et and E₆et. Eaq, E₃et, E₆et, and DMC strongly inhibiting the pancreatic α-amylase, with IC₅₀ values of 73.10, 165.93, 231.23?μg/ml, and 69.35?μM, respectively. Furthermore, the kinetic analysis suggested that the inhibition mode of crude extract against pancreatic lipase was noncompetitive, while that against pancreatic α-amylase was competitive. The content of DMC and total polyphenols in each extract were determined by HPLC and spectrophotometric method, respectively. It was interestingly found that the DMC content had profound influence on pancreatic lipase activity, and the total polyphenols content significantly affected the pancreatic α-amylase activity. The findings in this work suggested that extracts from C. operculatus flower buds possess potent inhibitory activity against pancreatic lipase and α-amylase, and provided some new ideas for the prevention and treatment for obesity.