Changes in content of organic acids and tea polyphenols during kombucha tea fermentation

Kombucha tea is a fermented tea beverage produced by fermenting sugared black tea with tea fungus (kombucha). Tea polyphenols which includes (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCG) and theaflavin (TF) have been reported to possess various biological activities. The present study focused on changes in content of organic acid and tea polyphenols in kombucha tea prepared from green tea (GTK), black tea (BTK) and tea manufacture waste (TWK) during fermentation. Concentration of acetic acid has reached maximum up to 9.5 g/l in GTK on 15th day and glucuronic acid concentration was reached maximum upto 2.3 g/l in BTK on 12th day of fermentation. Very less concentration of lactic acid was observed during the fermentation period and citric acid was detected only on 3rd day of fermentation in GTK and BTK but not in TWK. When compared to BTK and TWK very less degradation of EGCG (18%) and ECG (23%) was observed in GTK. TF and thearubigen (TR) were relatively stable when compared to epicatechin isomers. The biodegradation of tea catechins, TF and TR during kombucha fermentation might be due to some unknown enzymes excreted by yeasts and bacteria in kombucha culture.     

Changes in free-radical scavenging ability of kombucha tea during fermentation

Kombucha tea is a fermented tea beverage produced by fermenting sugared black tea with tea fungus (kombucha). Free-radical scavenging abilities of kombucha tea prepared from green tea (GTK), black tea (BTK) and tea waste material (TWK) along with pH, phenolic compounds and reducing power were investigated during fermentation period. Phenolic compounds, scavenging activity on DPPH radical, superoxide radical (xanthine–xanthine oxidase system) and inhibitory activity against hydroxyl radical mediated linoleic acid oxidation (ammonium thiocyanate assay) were increased during fermentation period, whereas pH, reducing power, hydroxyl radical scavenging ability (ascorbic acid–iron EDTA) and anti-lipid peroxidation ability (thiobarbituric assay) were decreased. From the present study, it is obvious that there might be some chances of structural modification of components in tea due to enzymes liberated by bacteria and yeast during kombucha fermentation which results in better scavenging performance on nitrogen and superoxide radicals, and poor scavenging performance on hydroxyl radicals.     

Characteristics and upregulation of antioxidant enzymes of kitchen mint and oolong tea kombucha beverages

Kombucha is a healthy traditional beverage which is made by fermenting products with a symbiotic culture of acetic acid bacteria and yeasts. In present study, leaves of kitchen mint (Mentha cordifolia Opiz. Ex Fresen) and leaves of oolong tea (Camellia sinensis) were fermented in kombucha formula. After fermentation, titratable acidity contents and ethanol of kitchen mint, oolong tea, and mixtures of oolong tea and kitchen mint kombucha samples gradually increased with a period of fermentation time. At day 14 of fermentation, phenolic compounds and flavonoids were increased in all kombucha samples. The numbers of acetic acid bacteria and yeast in kombucha had gradually raised during 7–14 days of fermentation. DPPH and ABTS scavenging activities of these kombucha increased over a period of fermentation time and shown the highest antioxidant capacity on day 14 of fermentation. In addition, all kombucha samples exhibited the antioxidant effects by attenuating H₂O₂-induced ROS production, increasing mRNA expression of catalase, glutathione reductase (GRe), and Mn-SOD, and inducing GRe enzymatic activity in HEK-293 cells. Kombucha beverage can be used as the healthy beverages for attenuation of oxidative stress in many diseases.     

A Review on Kombucha Tea—Microbiology,Composition, Fermentation,Beneficial Effects,Toxicity, and Tea Fungus

Fermentation of sugared tea with a symbiotic culture of acetic acid bacteria and yeast (tea fungus) yields kombucha tea which is consumed worldwide for its refreshing and beneficial properties on human health. Important progress has been made in the past decade concerning research findings on kombucha tea and reports claiming that drinking kombucha can prevent various types of cancer and cardiovascular diseases, promote liver functions, and stimulate the immune system. Considering the widespread reports on kombucha, we recognized the need to review and update the research conducted in relation to kombucha tea, its products and tea fungus. Existing reports have suggested that the protective effects of kombucha tea are as good as those of black tea, however, more studies on kombucha tea and its composition are needed before final conclusions can be made.     

红茶菌的研究和应用进展

红茶菌是具有悠久历史的功能性饮料,是由酵母菌、醋酸菌和乳酸菌以糖茶水为原料的微生物发酵饮料。近年来在许多国家兴起了红茶菌应用和研究的新高潮。本文综述了目前国内外有关红茶菌的菌种类型、功能成分及其作用、菌液抑菌及抗氧化活性、发酵产品的研制等方面的研究进展,并对红茶菌的应用前景进行了展望。     

三种砖茶品质生化成分的研究

通过比较三种砖茶中各种生化成分含量的差异,分析了不同加工工艺对砖茶生化成分以及成茶品质风味的影响。实验结果表明,黑砖茶的水浸出物、茶多酚、咖啡碱、游离氨基酸及三种色素的含量均为最高,茯砖茶次之,青砖茶最低,而可溶性糖的含量是黑砖茶最低,青砖茶最高。三种砖茶生化成分的差异主要是由不同的加工工艺造成的,茯砖茶有独特的"发花"工序,其品质表现为有菌花香,滋味醇和;黑砖茶的原料较嫩,加工过程比较简单,内含成分高,滋味表现为纯厚微涩;青砖茶的原料最为粗老,自然发酵时间长,可溶性糖含量高,其品质表现为香气纯正,滋味甘甜。     

发酵条件对红茶菌发酵品质及风味的影响

探究发酵条件对红茶菌发酵品质及发酵液风味的影响。以发酵产酸率、感官评分为指标,考察红茶品种、茶叶浸提方式、糖添加量、茶叶添加量及红茶菌膜接种量的影响;同时,对发酵过程中风味物质的变化进行分析。结果表明:将水煮沸后,加0.5%醇香红茶浸提15 min,加入7%糖,冷却后加8%红茶菌膜于30℃条件下发酵10 d,得到的产品感官品质好,发酵液呈清澈淡黄色,酸甜适中,微酸,口味纯;茶汤经发酵后风味物质显著改变,共检测到19种风味成分,其中醇类7种、酯类6种、酸类4种、酚类1种、烷烃类1种,即风味物质多为醇类、酯类和酸类。醇类的含量为25.09%,其中乙醇含量为21.51%;酸类的含量为46.40%,其中正辛酸含量为19.41%;酯类的含量为15.91%,其中乙酸乙酯含量为9.47%。     

酵母工程菌S.pombe yAS56的构建及魔芋红茶菌发酵工艺的研究

为研究利用魔芋精粉制备魔芋红茶菌的可行性,从约氏梭菌（Clostridium josui）中克隆β-葡聚糖酶基因cel9C,构建粟酒裂殖酵母（Schizosaccharomyces pombe）重组表达质粒p ESP-2-2-cel9C,转化构建酵母工程菌,利用工程菌进行魔芋红茶菌发酵。采用析因实验设计和中心组合实验设计方法,以总酸为响应值,优化发酵条件,从7个因素中筛选出2个显著因素:装液量和时间。最佳条件为:绿茶0.4%、蔗糖7.5%、魔芋精粉0.25%、接种量10%、酿酒酵母/酵母工程菌接种细胞浓度比=0.5、装液量98.7 m L、时间124 h。在此条件下红茶菌总酸为（27.88±0.26）g/kg,与预测值相近,较优化前提高41.45%,表明利用魔芋精粉和酵母工程菌制备魔芋红茶菌具有可行性。      

红茶菌发酵荞麦浆醋饮的工艺优化及品质分析

本文以荞麦浆为原料,采用红茶菌发酵荞麦浆制备荞麦浆醋饮。以荞麦浆发酵液总酸含量及感官评分为指标,探究不同荞麦浆可溶性固形物含量、红茶菌接种量、发酵温度对发酵液品质的影响,确定发酵最佳工艺条件;在最佳工艺条件下制备荞麦浆醋饮,探究发酵过程中荞麦浆pH、总酸、总酚、总黄酮及有机酸含量的变化。结果表明,红茶菌发酵荞麦浆醋饮最佳工艺条件为可溶性固形物含量13%,红茶菌接种量15%,发酵温度30 ℃;在此优化条件下,发酵过程中,荞麦浆pH降低、总酸升高,还原糖含量先升高后下降,总酚含量升高、黄酮含量先下降后升高,乙酸、乳酸、琥珀酸含量增加,苹果酸和丙二酸含量先增加后降低;发酵9 d后得到的荞麦浆醋饮总酸含量32.96 g/L,总酚含量1.72 g/L,总黄酮含量2.55 g/L,酸度适宜,口感柔和,具有浓郁的荞麦香气和保健功能。     

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)。     

姬松茸和双孢蘑菇固态发酵对小米蛋白质和多酚的影响

采用姬松茸和双孢蘑菇对小米进行固态发酵,并对发酵产物的蛋白质含量和氨基酸组成以及多酚含量进行了测定。结果显示:与未发酵的小米对照相比,姬松茸小米发酵产物和双孢蘑菇小米发酵产物中的粗蛋白、水溶性蛋白和氨基酸态氮含量均得到了显著提高（P<0.05）,其中粗蛋白含量分别提高了6.13%和12.25%,水溶性蛋白含量分别提高了10.37和4.64倍,氨基酸态氮含量分别提高了12.31和1.01倍,且两种小米发酵产物蛋白质的氨基酸评分、必需氨基酸指数（双孢蘑菇小米发酵产物除外）、营养指数以及与鸡蛋蛋白之间的贴近度均高于对照,这说明小米发酵产物的蛋白质质量高于对照;两种小米发酵产物中的游离态多酚和总酚含量显著高于对照（P<0.05）,游离态多酚含量达到3.91和1.57 mg GAE/g DW,分别是对照的4.55和1.82倍,总酚含量达到4.03和1.73 mg GAE/g DW,分别是对照的3.87和1.66倍。本实验结果表明,采用姬松茸和双孢蘑菇对小米进行固态发酵,可以提高小米的蛋白质质量和多酚含量。本实验可以为开发利用小米资源,增加小米附加值提供一定的理论依据,也可为开发利用食用菌资源提供一定的参考。     

Monitoring tea fermentation/manufacturing by direct analysis in real time (DART) mass spectrometry

Factors such as fermentation methods, geographical origin and season can affect the biochemical composition of tea leaves (Camellia sinensis L.). In this study, the biochemical composition of oolong tea during the manufacturing and fermentation process was studied using a non-targeted method utilising ambient ionisation with a direct analysis in real time (DART) ion source and mass spectrometry (MS). Caffeine dominated the positive ionisation spectra throughout the manufacturing process, while the negative ion spectra collected during manufacturing were rich in ions likely to be surface lipids. Correlation analyses on the spectra revealed two volatile compounds tentatively identified as indole and geranic acid, along with ammonium and caffeine clusters/adducts with geranic acid that increased in concentration during the fermentation stages of the process. The tentative identifications were assigned using a combination of DART-ion-trap MSⁿ and DART-accurate mass MS¹ and MS² on tea samples and standard compounds. This study highlights the potential of DART-MS to rapidly monitor the progress of complex manufacturing processes such as tea fermentation.     

茶菌人工复合菌剂构建和发酵性能分析

利用从茶菌中分离纯化的4个优势菌株构建人工复合菌剂。通过单独培养和不同复合方式培养的比较，确定菌株在茶菌发酵和菌膜形成中的作用；采用高效液相色谱、顶空固相微萃取和气相色谱-质谱联用等方法分析茶菌发酵过程中主要生化成分变化；经历多次传代接种后，采用人工分离和宏基因组分析相结合分析菌群组成和稳定性。结果表明：供试的4个菌株中，葡糖醋杆菌J5(Gluconacetobacter sp. J5)是产生纤维素和菌膜的核心菌株。混合菌株组合C3C5C6J5发酵后在菌体生长、糖利用、发酵液pH值、总酸度和茶多酚含量等指标与自然发酵相似。经历6代转接后菌群稳定，复配的菌株在人工菌群中均为优势菌株。表明从天然茶菌饮料中分离纯化功能菌株，通过菌株复配构建稳定的人工发酵剂可行，为茶菌的标准化工业生产打下基础。     

灰树花固体发酵茶青的研究

以茶青为发酵培养基质,对灰树花固体发酵过程中的各种内含物含量的变化及其品质进行了研究。结果表明,灰树花的最佳发酵培养基成分及培养条件:中叶茶,2%大豆粉,接种量1%,培养温度25℃,培养时间9d。发酵后其菌质的有效成分为:茶多酚1.78%,游离氨基酸0.77%,酚氨比2.3,多糖4.69%。与发酵前比较其多糖含量增加了31.7%,茶多酚降解了77.8%,游离氨基酸降低了26.7%,酚氨比降低了69.9%,茶叶品质得到很大改善。     

冠突散囊菌发酵杜仲茶的工艺优化

以杜仲叶为主要材料,探索冠突散囊菌发酵杜仲茶的最佳工艺条件。以发酵天数、接种量、含水量、渥堆温度、渥堆时间为单因素进行试验,并选取主要因素进行正交试验,并以孢子数、绿原酸含量及发花情况为评价指标,确定冠突散囊菌发酵杜仲茶的最佳工艺。研究表明:其最佳工艺条件为接种量20%、含水量35%、渥堆温度45 ℃、渥堆时间3 h、发酵时间为8 d,在此条件下,所制得的冠突散囊菌发酵杜仲茶金花茂盛,颗粒饱满,孢子数为1.13×10⁶ CFU/g干茶,绿原酸含量为0.478 mg/g,有金花独特香气且气味浓郁。     

微生物固态发酵和酶解工艺处理棉粕的研究

研究了微生物和蛋白酶共同作用下棉粕中毒性因子和营养成分的变化。在枯草芽孢杆菌GJ00141、酿酒酵母GJ00079和中性蛋白酶等参与的固态发酵和酶解体系中,检测棉粕中游离棉酚、粗蛋白质、酸溶蛋白质、粗纤维、氨基酸组成、益生菌活菌数等指标。结果发现,相比原棉粕,60 h的固态发酵与酶解后,棉粕中游离棉酚含量降低40%以上,酸溶蛋白质提高了108.7%,粗纤维降低约12.7%,枯草芽孢杆菌和酿酒酵母活菌数分别为7.75、7.00 lg(CFU/g),粗蛋白质、氨基酸总量基本没有变化。由此可见,经过发酵和酶解后棉粕的营养价值和饲料品质有所提高。     

淡竹叶茶营养成分分析

目的:研究淡竹叶茶的营养成分。方法:仿照茶叶加工工艺制备淡竹叶茶,按相关国标与方法测定其总黄酮、粗蛋白质、总糖、维生素、氨基酸及矿质元素等含量。结果:淡竹叶茶中总黄酮、粗蛋白、总糖及粗纤维含量分别为5.76%、36.1%、11.7%、17.9%。其含有8种必需氨基酸,谷氨酸含量最高,为1.168g/100g,必需氨基酸占总氨基酸的44.5%。淡竹叶茶中所含维生素以VC含量最高,为123.87mg/100g。矿质元素含量丰富,尤其是Mg、Mn,其含量分别为402.87、118.87μg/g,且含有一定量的Se。结论:淡竹叶茶有较高的营养价值,在医药食品行业有很好的运用前景。      

Effects of origins and fermentation time on the antioxidant activities of kombucha

Effects of kombucha origins and fermentation time on their antioxidant properties were investigated using in vitro free radical scavenging assays. Kombucha from various sources demonstrated different antioxidant activities, and most showed the time-dependent characteristics. The average antioxidant potentials of kombucha after fermenting for 15 days were raised to about 70%, 40%, 49% determined, respectively, by the assays of DPPH, ABTS radical scavenging, and inhibition of linoleic acid peroxidation, while the ferrous ion binding ability was inversely diminished by 81%. The total phenol content increased up to 98% which implied that thearubigin might be subjected to biodegradation during fermentation, resulting in the release of smaller molecules with higher antioxidant activities.     

冠突散囊菌对发花黑毛茶品质呈味成分的影响

目的探索湖南农业大学长安教学基地湘妃翠、碧香早和茗丰3个品种制成的黑毛茶经冠突散囊菌发花后其呈味品质成分的差异变化,对黑毛茶进行冠突散囊菌发花优化实验。方法采用国标检测方法对发花前黑毛茶及发花后成品茶其水浸出物、茶多酚、游离氨基酸、可溶性糖等呈味成分进行分析,对所测数据进行组间和组内方差分析。结果湘妃翠经发花后其水浸出物、茶多酚、游离氨基酸和生物碱在发花成品茶中下降幅度最大;碧香早经发花后其成品茶中茶多酚、游离氨基酸与其原料茶相比显著下降;茗丰经发花后其茶多酚、氨基酸和生物碱与其原料茶相比显著下降,而可溶性多糖显著增加。结论在三个发花成品茶中,以湘妃翠化学品质表现最为突出,湘妃翠较碧香早、茗丰更适制发花黑茶,其次为茗丰。     

广西三个产区虫茶主要茶特征成分、挥发性成分分析及氨基酸营养评价

对广西三个主产区虫茶的主要茶特征成分、挥发性成分及氨基酸组成进行了分析,并采用氨基酸比值系数法对其氨基酸特性及营养价值进行评价。结果表明:广西虫茶内含物丰富且具有低咖啡碱高氨基酸的特性,不同产区虫茶的水浸出物、氨基酸、茶多酚均存在极显著差异（P<0.01）。三个产区虫茶共检测出36种挥发性成分,不同产区挥发性成分差异较大,融安以醇、酮类为主,龙胜以醛、酯类为主,三江以酸、酯类为主。此外,不同产区虫茶氨基酸各组分差异较大,其中组氨酸（His）、甘氨酸（Gly）有显著性差异（P<0.05）,精氨酸（Arg）、天门冬氨酸（Asp）等其他14类氨基酸均有极显著差异（P<0.01）;必需氨基酸/总氨基酸（EAA/TAA）与必需氨基酸/非必需氨基酸（EAA/NEAA）达到了WHO/FAO提出的理想蛋白质人体必需氨基酸模式;三个产区虫茶均含有9种药用氨基酸（MAA）,MAA/ TAA均值高达62.26%。氨基酸比值系数法评定可知三个产区虫茶的第一限制氨基酸均为蛋氨酸（Met）+胱氨酸（Cys）,赖氨酸（Lys）为龙胜、三江两个产区的第二限制氨基酸,其他必需氨基酸均接近或高于模式蛋白;同时,三个产区氨基酸比值系数分（SRCAA）在71.33~77.96之间,必需氨基酸指数（EAAI）均大于1,由此可见广西虫茶是一种优质蛋白质资源的选择,有作为保健饮料进行开发的潜力。