Evaluation of microbial toxins,trace elements and sensory properties of a high-theabrownins instant Pu-erh tea produced using Aspergillus tubingensis via submerged fermentation

Theabrownins (TB) are polymeric phenolic compounds associated with the multiple bioactivities of Pu-erh tea, a post-fermented Chinese dark tea. High-TB instant Pu-erh tea was produced via a novel submerged fermentation (SF) using Aspergillus tubingensis and compared with samples produced commercially via the conventional solid-state fermentation (SSF). Viable microorganisms and microbial toxins, especially aflatoxins B₁, G₁, B₂, G₂, cyclopiazonic acid, fumonisins B₁, B₂, B₃ and ochratoxin A, were below the detection limit in all samples. Fewer microbial metabolites were found in SF instant tea compared with the SSF teas. Based on an adult consuming 1 g of instant Pu-erh tea daily, the dietary intake of investigated elements was below the safe limits recommended by various authorities. Tasters viewed the instant tea infusions as very mild, smooth, mellow and full. This suggested that submerged fermentation using A. tubingensis offers a speedy and safe alternative to commercial production of instant Pu-erh tea.     

Effects of enzymatic action on the formation of theabrownin during solid state fermentation of Pu-erh tea

BACKGROUND: Theabrownin (TB) is a main bioactive component in Pu‐erh tea, and the total amount is between 100 and 140 g kg^?1. However, reports on the mechanism of formation of TB are sparse because it has a high molecular weight and complex composition. Hence, the mechanism of formation of TB in Pu‐erh tea during solid state fermentation was investigated using an exogenous enzyme method. RESULTS: It was found that, in the presence of exogenous enzymes, the tea liquor prepared from the resulting leaves changed considerably in colour. In addition, the TB, total carbohydrate, polysaccharide, amino acid and protein contents were all increased, while the tea polyphenol content decreased sharply; the surfaces of leaves before fermentation appeared to be smooth and intact, and the structures of the cell, cellulose and lignin were complete, while after fermentation their surfaces were covered by microorganisms and the structures of the cells were largely disrupted. CONCLUSION: The enzymatic actions are closely related to the compositional changes occurring during Pu‐erh tea manufacture, and its quality. Enzymes produced by microorganisms were found to be the main cause of TB formation during the fermentation of Pu‐erh tea. Copyright © 2011 Society of Chemical Industry     

发酵方法对普洱茶茶褐素样品组成的影响

采用水提醇沉法从塔宾曲霉液态发酵普洱茶粉和传统固态发酵工艺所产普洱熟茶中提取茶褐素。应用居里点热裂解气相色谱-质谱联用技术及比色法研究液态发酵茶褐素样品和固态发酵茶褐素样品的化学组分。结果显示,液态发酵样品中的茶褐素、总多酚、总黄酮、总儿茶素和氨基酸显著高于固态发酵样品（P＜0.05）;液态发酵样品中的总糖、多糖、茶黄素显著低于固态发酵样品（P＜0.05）;液态发酵样品与固态发酵样品的蛋白质含量差异不显著（P＞0.05）。在不同居里点热裂解温度下,固态发酵样品与液态发酵样品的裂解产物分别有12?种（380?℃）和9?种共同成分（600?℃）,两者在不同温度下的裂解产物中,酚类种类最多,含量最高的化合物是咖啡因。     

Quality identification and evaluation of Pu‐erh teas of different grade levels and various ages through sensory evaluation and instrumental analysis

To develop an objective, effective, flexible and cost‐saving method to assess Pu‐erh tea quality, Pu‐erh tea samples of different grade levels and various ages were analysed using sensory evaluation and various instrumental techniques, including chemical analysis and electronic tongue (ET). Results showed that taste profile analysis as a sensory evaluation method can meticulously describe and distinguish different Pu‐erh tea samples. Chemical analysis combined with hierarchical cluster analysis can cluster Pu‐erh ripened and raw tea both in compressed and scattered forms. However, no obvious variation tendency was observed in the chemical composition parameters of Pu‐erh tea of different grade levels or various ages. ET combined with principal components analysis (PCA) is effective in classifying Pu‐erh tea samples of different grade levels and various ages. ET followed by linear discriminant analysis (LDA) performs well in identifying Pu‐erh tea samples of various ages by establishing a discriminant model.     

人工接种真菌固态发酵对普洱茶品质和功能的影响

本实验以人工接种黑曲霉、青霉、酵母三种真菌固态发酵和自然渥堆发酵加工而成的普洱茶为材料,对比研究其感官品质、理化品质、香气成分和微生物安全指标,并探讨其在降糖和抗癌等保健功能方面的异同。结果表明：人工接种黑曲霉、青霉和酵母三种真菌固态发酵普洱茶能保持自然渥堆发酵普洱茶的基本品质,其产品汤色、滋味、香气等感官品质优良,水浸出物、茶多酚二项理化指标较自然渥堆发酵的茶样（对照）优越,大肠杆菌含量低于30MPN/100g,致病菌未检出,符合云南省地方标准DB53/103-2006的安全指标要求;在活性功能方面,人工接种黑曲霉、青霉和酵母三种真菌固态发酵的普洱茶在防治胃癌和努南氏综合症上效果较好,对于降糖和减肥、免疫缺陷疾病和白血病、血液疾病的防治效果来看,则稍次于自然渥堆发酵的普洱茶,二者表现出大同小异,各有优势,各具特色。     

酵母菌纯种发酵普洱茶初探

酵母菌是普洱茶发酵过程中的优势菌种之一,含有极丰富的对人体有益的营养物质、丰富的酶系统和生理活性物质,此外还能代谢产生VB1、VB2、Vc等物质,是形成普洱茶甘、滑、醇品质风格的重要因子。对从普洱茶渥堆发酵样品中分离出的5株优势酵母菌进行纯菌接种发酵试验,并对发酵后的茶样进行化学成分检测和感官评价,结果发现,酵母菌株Y5能将生茶的多酚值由28.33%降至14.54%,将茶褐素值由2.45%增至6.86%,在5株酵母菌发酵的茶样中,其茶褐素增幅最为显著。另外Y5发酵的茶样有香甜味,其滋味略苦,生津,有回甘,可以用来提高普洱茶的香气和滋味。     

冠突散囊菌固体发酵铁观音茶的主要活性成分及其抗氧化性分析

为提高铁观音茶青的利用率,采用冠突散囊菌固体发酵铁观音茶,检测发酵前后茶叶中化学成分和抗氧化性的变化。结果表明,铁观音茶叶经发酵后,与未发酵的对照组茶叶相比,多酚、表没食子儿茶素没食子酸酯（EGCG）、表儿茶素没食子酸酯（ECG）、茶黄素,游离氨基酸、麦芽糖、蔗糖和果糖等物质的含量显著性降低（P<0.05）,尤其EGCG和ECG分别下降了92.2%和88.1%,而总黄酮、表没食子儿茶素（EGC）、儿茶素（+C）、表儿茶素（EC）、总糖、葡萄糖、三萜类物质、茶红素和茶褐素等物质的含量显著性增加（P<0.05）,尤其茶褐素增加了68.4%。经过冠突散囊菌发酵过的茶叶与对照茶叶相比总还原力和Fe3+还原能力,清除DPPH自由基、ABTS+自由基、羟基自由基能力仍然很强。综上,冠突散囊菌的固体发酵降低了茶叶中具有苦涩味道的茶多酚,增加了总糖、茶红素、茶褐素、EGC、+C、EC等含量,研究为铁观音茶青的发酵利用提供了实验依据。     

Production of yellow wine from Camellia Oleifera meal pretreated by mixed cultured solid‐state fermentation

Camellia oleifera meal was evaluated to be a potential feedstock for the production of yellow wine (YW), and process conditions were investigated. In this study, C. oleifera meal was firstly pretreated using mixed cultured Bacillus subtilis and Aspergillus niger under solid‐substrate fermentation to degrade the tea saponin (TS) for the following YW fermentation. Response surface methodology helped evaluate the effects of the selected operating parameters, and the optimal condition at a fixed time of 4 days, which gave a 67.84 ± 0.23% degradation rate of TS, was reached as inoculum concentration of 16%, initial moisture content of 55% and temperature of 30 °C. Finally, 7‐day fermentation was harvested to be the most suitable pretreatment for producing YW from C. oleifera meal, and the twice‐feeding fermentation for YW was obtained as wheat koji 12% and active yeast 1.2%. In addition, ample amino acids, phenolic components and the trace TS endowed the C. oleifera wine, the more nutritional characteristics.     

泾渭茯砖茶发酵过程中霉菌的变化

茯砖茶发源于陕西泾阳,属于后发酵茶,霉菌是其发酵过程中起重要作用的菌,泾渭茯砖茶是茯砖茶的代表.本研究分析了泾渭茯砖茶发酵过程中的12个不同阶段(0、2、4、6、8、10、12、14、16、18、23、28 d)可培养霉菌的变化,结果表明,发酵过程中参与的霉菌有8种,分别为冠突曲霉(Aspergillus crista...     

Metabolic Changes during the Pu‐erh Tea Pile‐Fermentation Revealed by a Liquid Chromatography Tandem Mass‐Spectrometry‐Based Metabolomics Approach

In the current study, liquid chromatography‐mass spectrometry combined with multivariate statistical analyses was employed to investigate the time‐varying biochemical changes during the pile‐fermentation process with the emphasis on the active ingredients to clarify the manufacturing process of ripened pu‐erh tea as a whole. The metabolite profiles of different manufacturing processes were unique and could be distinguished with the aid of principal component analysis. Furthermore, partial least‐squares discriminant analysis revealed a pairwise discrimination between the raw material group and pile‐fermentation process groups or the final product group, and 48 differential metabolites with variable importance in the projection value greater than 1 were identified, which was confirmed by the subsequent hierarchical cluster analysis. These results highlight our current understanding of the exact changing process of the bioactive compounds during the pile fermentation, and the global change of these bioactive compounds provides the special flavor, taste, and health promoting effects of ripened pu‐erh tea.     

六堡茶渥堆过程中可培养微生物的分离与鉴定

采用传统微生物分离和分子鉴定技术对六堡茶渥堆过程的样品中微生物多样性进行研究。从不同渥堆阶段的样品中分离出细菌13个属、27个种,放线菌7个属、8个种,真菌11个属、23个种,其中黑曲霉、塔宾曲霉、Blastobotrys adeninivorans和芽孢杆菌属在整个渥堆过程中都检出。本研究所有分离鉴定得到的细菌22种、放线菌7种和真菌9种均为六堡茶中首次发现与报道。本研究有利于了解六堡茶渥堆工艺的微生物作用,并对六堡茶的纯种发酵和微生物安全性分析提供理论依据。     

茯砖茶优势菌株分离鉴定及发酵低级绿茶分析

对湖南白沙溪茯砖茶中的优势菌株进行分离、纯化,并通过形态学分析和ITS序列比对进行鉴定.以云南大叶种低级绿茶为原料进行纯菌发酵,分析发酵液主要成分含量的变化.结果表明:从湖南白沙溪茯砖茶中分离得到的4株优势菌株,其中J1被鉴定为谢瓦曲霉(Aspergillus chevalieri);J2、J3和J4均被鉴定为冠突曲霉...     

高效降解茶皂素菌株的分离鉴定及其发酵优化研究

从自然发酵的油茶饼粕中筛选到一株对油茶饼粕中茶皂素具有较强的降解能力的菌株L-2。通过菌株的形态学鉴定和ITS rDNA序列分析确定该菌株的系统发育地位。研究固态发酵中发酵时间、发酵温度、初始含水量和初始加酸量对该菌株降解油茶饼粕中的茶皂素的影响。结果表明:菌株L-2为黑曲霉(Aspergillus niger),经过单因素实验和响应面实验优化后的最适降解条件为发酵温度31.3℃,发酵时间103.5 h,初始加酸量4.57 mL,初始含水量80%,此时黑曲霉L-2对油茶饼粕中茶皂素的降解率为93.96%。     

Quality Characteristics of a Pickled Tea Processed by Submerged Fermentation

There is a traditional pickled tea fermented under anaerobic condition in many Asian countries, but its quality characteristics are still unclear. The dynamic qualities, chemical components, and volatile components of pickled tea processed by submerged fermentation were investigated. The results showed that the sensory qualities of the pickled tea gradually improved with increasing fermentation time. Sensory qualities decreased gradually after 7 d of fermentation, and the change was extremely significant (p < 0.01). Correspondingly, biochemical indicators (except for soluble extract) decreased continuously and significantly (p < 0.01) within 5–7 d of fermentation, but the decrease was much slower in the later stage. The proper control of fermentation time is a key step for obtaining the desired quality of pickled tea. By submerged fermentation for 7 d, the best sensory quality of pickled tea was obtained: the taste of pickled tea was less bitter and astringent, but certainly acidic; the flavor of pickled tea was sour with sweet and floral tastes; the tea had low caffeine content, high gamma-amino butyric acid content, and high contents of special volatile components, such as hotrienol and 2,6-bis (1,1-dimethylethyl)-4-methyl-phenol. Results indicated that submerged fermentation is potentially a new method of processing pickled tea to obtain the desired quality. Our results contribute to the understanding of the microbial transformation of tea components under anaerobic conditions.     

Preparation of an Alcoholic Beverage from Tea Leaves

The preparation of a fermented tea beverage from a Sri Lankan Broken Orange Pekoe (BOP) tea type is reported. The tea beverage was produced using 1–2.5% (w/v) Broken Orange Pekoe and was brewed using boiling sucrose sweetened (5–25°Brix) water (100°C for 3 min), followed by fermentation at 25°C, utilizing an 8.5% (v/v) inoculum of Saccharomyces cerevisiae G. A maximum ethanol of 14.91% (v/v) was obtained from an initial 25°Brix substrate with a 2.67°Brix drop per day. The tea beverage with an initial 15°Brix and 1.5% (w/v) tea yielded the best sensory score and was stable over a test period of 6 weeks at 15°C.     

普洱茶中转化茶多酚的优势菌株筛选与鉴定

普洱茶是以晒青毛茶为原料,采用独特工艺加工而成的一种发酵性茶叶,其中微生物的发酵对普洱茶的品质形成起着决定性作用。为了提高普洱茶品质和缩短发酵周期,本研究对普洱熟茶样品中转化茶多酚的微生物进行筛选与鉴定。经过固体平板初筛和液体茶汤培养复筛,得到3株氧化茶多酚形成茶褐素能力较强的菌株。将这3株菌回接普洱茶固态发酵,明显促进了茶多酚转化为茶色素,并改善了3种茶色素的比例。分子生物学鉴定结果表明,这3株菌分别为黑曲霉(Aspergillus niger)、布朗克假丝酵母(Candida blankii)和泡盛曲霉(Aspergillus awamori)。     

黑茶优势菌对绿茶浸提液发酵过程多酚类化合物的影响

利用从普洱茶中分离出的黑曲霉、根霉和从茯砖茶中分离出的冠突散囊菌接种云南大叶种晒青毛茶茶汤,进行单一菌株发酵,对发酵过程茶多酚类化合物的含量变化进行分析。结果表明：随着发酵时间的延长,茶多酚含量显著降低,黄酮类化合物总量在黑曲霉、冠突散囊菌作用下分别减少72%、31.76%,在根霉作用下增加了94.92%;儿茶素各组分的含量变化较大,其中表没食子儿茶素、表没食子儿茶素没食子酸酯、表儿茶素、表儿茶素没食子酸酯均呈现显著的下降趋势,而儿茶素、没食子酸在不同菌株作用下表现出不同的变化规律;茶黄素在黑曲霉、根霉作用下先增加后减少,冠突散囊菌则相反;茶红素总体呈下降趋向,茶褐素在根霉、冠突散囊菌作用下显著增加。     

Bacterial and Fungal Communities in Pu'er Tea Samples of Different Ages

Pu'er is a major kind of postfermented tea and is made with a “large leaf” variety of Camellia sinensis (C. sinensis assamica), whose distribution is limited to the mountains of southern Yunnan, China. The quality of Pu'er tea is believed to increase with storage (aging, maturing) because of postfermentation by microbes. The effect of storage period (from < 1 to 192 mo) on the bacteria and fungi in Pu'er tea was investigated by a culture‐dependent and a PCR‐DGGE method. The individual numbers of fungi and bacteria decreased with increasing storage time and were significantly greater in ripened tea than in raw Pu'er tea. Both methods indicated that yeast, Aspergillus spp., and Penicillium spp. were the dominant fungi in almost all the samples. However, the common bacteria detected by the culture‐dependent method were species of Pseudomonas, Achromobacter, Alcaligenes, Sporosarcina, and Bacillus, whereas those detected by PCR‐DGGE were species of Staphylococcus, Arthrobacter, and Streptomyces. According to ordination analysis, bacterial community structure differed between ripened and raw Pu'er tea. Bacterial diversity was positively correlated with aging time, while fungal diversity in both raw and ripened tea increased during the first 60 mo of aging and then decreased. Changes in polyphenol content were correlated with the changes in fungal diversity. These results suggest that the relationship between storage time and the quality of Pu'er tea is complex and involves changes in polyphenol content and microbial abundance and diversity.     

不同潮水量条件下普洱茶渥堆过程化学成分的变化

通过设置不同潮水量进行实验室模拟普洱茶渥堆过程,系统地研究堆表与堆芯主要理化成分含量的变化规律,找出普洱茶快速模拟发酵的潮水量。结果表明：至渥堆结束,茶坯的茶多酚、儿茶素、茶黄素、茶红素、氨基酸的含量均呈减少趋势,水溶性糖、茶褐素、咖啡碱的含量则呈增加趋势。不同潮水量条件下渥堆茶样的堆温以及参与发酵的微生物的差异,显著地影响普洱茶的品质。结合感官评价得出,潮水量为45%的普洱茶表现出较佳的品质。     

Analysis of characteristic aroma of fungal fermented Fuzhuan brick‐tea by gas chromatography/mass spectrophotometry

Fuzhuan brick‐tea is a popular fermented Chinese dark tea because of its typical fungal aroma. Fungal growth during the production process is the key step in achieving the unique colour, aroma and taste of Fuzhuan brick‐tea. To further understand the generation of the characteristic aroma, changes in the main volatile compounds of Fuzhuan brick‐tea during the fungal growth stage were studied by gas chromatography/mass spectrophotometry. The results showed that the content of volatile compounds, especially aldehyde compounds with stale aroma such as (E)‐2‐pentenal, (E)‐2‐hexenal, 1‐penten‐3‐ol, (E, E)‐2,4‐heptadienal and (E, Z)‐2,4‐heptadienal, increased significantly in fermented tea samples. The concentration of terpene alcohols with flower aroma also increased notably during the fermentation process. The compounds with stale and flower aromas in combination with some volatile components of the raw material contributed to the characteristic ‘fungal/flower’ aroma of Fuzhuan brick‐tea. Microbial metabolism during the fermentation process probably played the key role in the generation of characteristic aromatic compounds of Fuzhuan brick‐tea. Copyright © 2007 Society of Chemical Industry