普洱茶后发酵过程中微生物的研究进展

对有关普洱茶后发酵生产与微生物的关系、微生物的种类、微生物对普洱茶品质的影响以及主要微生物的生长特性等方面的研究工作进行综述。指出加强普洱茶后发酵过程中微生物基础研究的必要性,提出建立普洱茶后发酵菌物库,重视对影响普洱茶品质的菌物开展系统研究的建议。     

普洱熟茶化学成分的HPLC-DAD-MS分析

普洱熟茶以其特殊的香气、口感和保健功效,近年来受到愈来愈多消费者的喜爱,是最受欢迎的茶叶品种之一.普洱熟茶由普洱生茶经特殊的微生物后发酵过程生产而成,而普洱生茶则以大叶茶的鲜叶为原料,是一种不发酵的绿茶.本文采用HPLC-DAD-MS技术,对普洱熟茶的化学成分进行了分析,从中共检测出21个峰;通过[M+H]+、[M-H]和碎片离子峰,以及与标准品对比,其中18个峰的化学结构分别得到了鉴定.研究结果显示,去除了大量存在的咖啡因后,HPLC-DAD-MS技术可以用于快速有效地检测普洱熟茶中的化学成分.     

黑曲霉及其与普洱茶品质关系研究进展

近年来,黑曲霉菌的研究受到了国内外大量学者的重视,并取得了一系列新进展,这些进展主要集中在:黑曲霉的分离鉴定方法;黑曲霉发酵生产多酚氧化酶、果胶酶和纤维素酶等酶类的机理;黑曲霉对普洱茶色泽、滋味和香气的影响等方面。文章集中对近年来黑曲霉及其与普洱茶品质形成相关的研究进展作简要综述,以期为黑曲霉在普洱茶中研究利用提供一定的参考。     

曲霉属真菌在普洱茶后发酵中的作用

为阐明微生物在普洱茶后发酵过程中的作用及其机制,本文进行了普洱茶温湿度试验,并利用从普洱茶后发酵堆中分离鉴定的优势曲霉属真菌,进行接种试验和专用菌剂的发酵生产试验.结果提示,只有在微生物的作用下,普洱茶才具特有的感官特性,曲霉属真菌能控制后发酵的过程,改变茶叶的感官特性.曲霉属真菌的种类及组合对普洱熟茶的茶多酚组成与含量,以及没食子酸、茶氨酸、咖啡因等特征成分的含量均有显著的影响.因此,应用专用菌剂进行后发酵生产,能加快普洱茶的熟化速度,提高发酵成功率,保证产品质量的稳定性,使普洱熟茶的规范化生产成为可能.     

8-氧化咖啡因和嘧啶类生物碱在普洱熟茶中的存在

应用柱层析分离技术,从普洱熟茶中首次分离到8-氧化咖啡因,嘧啶类生物碱(胸腺嘧啶脱氧核苷、胸腺嘧啶和尿嘧啶) ,黄酮类配糖体(黄杞甙) ,以及简单酚类化合物(1 ,2 ,4-苯三酚、1 ,3-苯二酚和4-甲基-1 ,2-二苯酚)。由于普洱熟茶是由大叶茶经微生物后发酵生产的, 8-氧化咖啡因显然是茶叶中的咖啡因在微生物作用下形成的转化产物。胸腺嘧啶脱氧核苷亦可能是茶叶中的嘧啶类生物碱与微生物中的核苷类化合物在后发酵过程中缩合形成的。二者均为新发现的普洱熟茶的特征性成分。     

普洱茶渥堆发酵与堆肥渥堆发酵的比较研究

普洱茶的自然渥堆发酵工艺与农业及环保中的堆肥发酵工艺在堆垛方法、堆垛形状和大小、自然升温过程、高温发酵、翻堆工艺等方面有许多相似之处,主要差别是原料和含水量的不同。对不同原料堆肥已有详细的研究及其动态菌群和多种发酵剂的研究和应用报道,明确了高温菌在渥堆发酵过程中起重要作用,对其翻堆工艺也有较详细的参数及其机械化的应用,但普洱茶渥堆发酵基本上还停留在自然发酵、人工翻堆、常温菌的研究及老茶头作发酵剂的应用等水平上。堆肥的许多研究手段和方法甚至物质转化、脱毒、高温菌的研究等都值得普洱茶渥堆发酵研究加以借鉴。     

普洱茶的香气成分

普洱茶（普洱熟茶）是以云南特有的大叶种茶制作的晒生毛茶（普洱生茶）为原料,经特殊的后李譬过程生产而成。与其原料晒青毛茶相比较,普洱茶的各类化学物质均发生了较大变化。本文应用气相色谱（GC）及气质联用（GC／MS／DS）技术,对云南临沧市生产的普洱茶和晒青毛茶等的香气成分进行分析比较。结果表明,普洱茶香气成分中的萜类、芳香族、以及有机酸类等化合物的组成和含量均与同一产地的晒青毛茶等均有显著的差异。     

普洱茶发酵前后对PTPs靶标抑制效果的比较

用不同品种无性系茶树良种制成普洱生茶和普洱熟茶,进行PTP1B、TCPTP、SHP-1、SHP-2、HePTP、YopH的靶标对比试验,结果表明经自然渥堆发酵的普洱熟茶对六个靶标的的抑制效果明显好于普洱生茶,说明普洱茶的发酵工艺是形成其特有保健功效的关键所在;另外,普洱熟茶对靶标的抑制效果还与其原料有关,在研究的3个大叶种茶中,对六个的靶标的平均半数抑制浓度(IC50)为云抗10号<云抗14号<大黑茶。     

普洱茶后发酵中咖啡碱变化研究进展(综述)

普洱茶（熟茶）的后发酵加工工艺,是形成其独特品质特征的关键工序。咖啡碱是一种甲基黄嘌呤,是茶叶中含量比较丰富的生化成分之一,也是茶叶主要呈味物质和生理活性成分,具有促进兴奋、强心、解毒、利尿、助消化等功效。咖啡碱在普洱茶后发酵过程中呈增加趋势。文章对普洱茶后发酵过程中咖啡碱变化的相关研究进行系统综述,为普洱茶咖啡碱理论研究提供科学依据。     

核基因组微卫星标记揭示大理茶参与了普洱茶的驯化过程

利用11个核基因组微卫星标记对普洱茶3个居群、大理茶3个居群及过渡型大理茶2个居群共104株古茶树进行了遗传学分析。研究表明,普洱茶、大理茶和过渡型大理茶居群的遗传多样性相对较低,平均等位基因(Na)为4.852,平均香农多样性指数(I)为1.17,平均期望杂合度(He)和观测杂合度(Ho)分别为0.59和0.52,其中大理茶的遗传多样性水平低于普洱茶和过渡型大理茶。AMOVA分析表明,普洱茶和大理茶之间遗传分化显著(FST=0.305),遗传变异主要在居群内(分别为93.51%和89.41%),而居群间的遗传变异较低(分别为6.49%和10.59%)。主成分分析和STRUCTURE聚类分析均支持大理茶和普洱茶为不同的组,过渡型大理茶主要由大理茶驯化而来,并在栽培过程中与大理茶产生了遗传分化。在混栽的大理茶和普洱茶居群间存在由大理茶向普洱茶的明显基因渐渗,证实了大理茶参与了普洱茶的驯化过程。最后,讨论并提出了对大理茶和普洱茶古茶树资源保护的相关建议。     

普洱茶减肥、降脂机制的探讨

普洱茶(Pu-erh tea)产于云南省南部地区,具有悠久的发展历史和丰富的文化涵蕴,被认为具有减肥、降脂、降血糖、防止心脑血管疾病等代谢性疾病功效.近几年来在人、啮齿类和细胞水平的研究表明,普洱茶的确具有减肥、降脂功效,普洱茶中的茶色素、多糖、多酚和他汀类物质可能通过抑制脂肪合成、促进脂肪氧化分解而发挥其减肥、降脂功效.本文综述了目前关于普洱茶减肥、降脂的生物学功效、活性成分、以及作用机制的相关报道,同时探讨了该领域未来的一些研究方向.     

Antibacterial property and mechanism of a novel Pu-erh tea nanofibrous membrane

Pu-erh tea is made via a natural fermentation process. In this study, Pu-erh tea was used as a raw material for nanomaterials preparation and as an antibacterial agent. Antibacterial activities on Escherichia coli of Pu-erh tea, Pu-erh tea powder (PTP) of different sizes, and Pu-erh tea residual powder were firstly determined, respectively. With polyvinyl alcohol as the carrier, through an electrospinning technique, different kinds of nanofibrous membranes were obtained from the extract of Pu-erh tea and nano-PTP (NPTP), and their antibacterial properties and mechanism against E. coli were evaluated. The results showed better antibacterial activity with smaller PTP particles, the nano-sized particles had the best effects, and the MIC of NPTP was 13.5 mg/mL. When NPTP was in nanofibrous membranes, the antibacterial activity decreased slightly, but increased with modification by ZnO. Pu-erh tea in nanofibrous membranes damaged the E. coli cell membranes and caused leakage of K⁺ and enzymes. What is more is that damage of the cell walls led to the leakage of fluorescent proteins from enhanced green fluorescence protein-expressing E. coli. These results indicate that the Pu-erh tea nanofibrous membranes had good antibacterial activities against E. coli, which may provide a promising application of novel antibacterial materials.     

普洱茶减肥、降脂机制的探讨

普洱茶(Pu-erhtea)产于云南省南部地区,具有悠久的发展历史和丰富的文化涵蕴,被认为具有减肥、降脂、降血糖、防止心脑血管疾病等代谢性疾病功效。近几年来在人、啮齿类和细胞水平的研究表明,普洱茶的确具有减肥、降脂功效,普洱茶中的茶色素、多糖、多酚和他汀类物质可能通过抑制脂肪合成、促进脂肪氧化分解而发挥其减肥、降脂功效。本文综述了目前关于普洱茶减肥、降脂的生物学功效、活性成分、以及作用机制的相关报道,同时探讨了该领域未来的一些研究方向。     

普洱茶中微生物的筛选及其安全性初步评价

目的在对普洱茶中微生物筛选和鉴定基础上对蜡样芽胞杆菌毒素基因的分布、普洱茶下调毒素基因的表达和改善肠上皮细胞的损伤进行研究。方法分别采用无菌水和沸水泡制普洱茶,获得分离株,通过16SrDNA测序以及生理生化试验确定其归属;对所筛选的菌株进行耐模拟胃肠液能力评价和毒力基因的检测;采用细胞实验和荧光定量PCR技术,研究普洱茶对蜡样芽胞杆菌毒素的抑制作用。结果无菌水浸泡普洱茶获得的45株菌中44株为芽胞杆菌属,沸水浸泡获得的7株菌均为蜡样芽胞杆菌(FBCE01、FBCE06、FBCE10、FBCE14、FBCE20、FBCE26和FBCE29),多重PCR技术结果表明其分别含有毒力基因cytK、nheA和hblD的2种或3种。耐模拟胃肠液实验表明,7株菌均具有很强的耐模拟胃肠液消化能力;细胞实验结果发现,普洱茶汤能显著降低蜡样芽胞杆菌对Caco-2细胞的粘附(P0.05);MTT实验结果显示,普洱茶能有效降低蜡样芽胞杆菌对细胞的损伤;荧光定量PCR技术结果进一步说明,普洱茶使蜡样芽胞杆菌肠毒素的mRNA表达水平下调。结论普洱茶具有抑制蜡样芽胞杆菌毒素的作用。     

Black tea,green tea,and tea polyphenols

Previous studies have shown that tea consumption can impair trace element metabolism, particularly iron status, and increase the risk of anemia in humans and animals. More recently, however, evidence has been accumulating to show that, in animals, consumption of green tea or its polyphenols is associated with a reduction of the incidence and severity of a variety of experimentally induced cancers. In this study we have monitored the growth, trace element status, including hematological parameters of weanling rats given either (1) water, (2) 1% black tea, (3) 1% green, tea, or (4) 0.2% crude green tea extract as their sole drinking fluid while consuming diets containing either adequate or low amounts of iron. With the exception of manaanese, none of the trace elements studied (iron, copper, zinc, and manganese) or the hematological indices measured were affected by the type of beverage supplied, even though the polyphenol extract was shown to chelate metals in vitro and all the animals fed the low iron diet were shown to be anemic. There appeared to be an effect of black and green teas on manganese balance in, both the first and last weeks of the study. A lower level of brain managanese was associated with green tea consumption, and a higher level of this element in the kidneys of animals fed black tea. The results demonstrate that both black and green teas and a green tea polyphenol extract do not represent a risk to animals consuming the beverages as their sole fluid intake with respect to iron availability, although the interactions with manganese deserve further study.     

EUF-analysis of tea soils of Southern India and tea productivity

Summary The relationship between EUF extractable nutrients and conventional soil test extractable nutrients in the acid soils of Southern India on one hand and that between EUF values and tea productivity on the other are described. Close correlation exists between EUF-NO₃–N at 20°C and CuSO₄–Ag₂SO₄-extractable NO₃–N (r=0.98^***), EUF-N_org and Morgan's reagent extractable NH₄–N (r=0.97^***), total EUF-N and CuSO₄–Ag₂SO₄-extractable NO₃–N plus Morgan's reagent NH₄–N (r=0.96^***), EUF-P at 20°C and modified Bray II-P (r=0.93^***) and EUF-P at 20°C plus that at 80°C and modified Bray II-P (r=0.91^***). The EUF-K at 20°C shows close correlation with NH₄OAc–K (r=0.80^***), Ag-thiourea-K (r=0.86^***) and Morgan's reagent-K (r=0.84^***) whereas the EUF-K at 80°C shows close correlation with the difference in K contents of NH₄OAc–K and Ag-thiourea-K (r=0.92^***) or of NH₄OAc–K and Morgan's reagent-K (r=0.93^***) and fixed NH₄–N (r=0.89^***). EUF-Ca, EUF-Mg and EUF-Mn do not show any relationship with conventional soil test values. Tea productivity is strongly associated with EUF-N and EUF-P extracted at 20°C.     

Studies of cocoa tea, a wild tea tree containing theobromine

Camellia ptilophylla Chang is a wild tea tree containing theobromine and is caffeine-flee. Lots of researches have been conducted for its domestication since it was discovered to contain theobromine in its shoots. First, its pharmacological and physiological effects have been studied, demonstrating that it can be used as a new resource of tea as daily and healthy beverage. Cocoa tea differs from traditional tea in that it does not excite the nervous system. Second, various ways of propagation have been investigated, and sexless cutting has been the method adopted currently. Third, through selection and breeding, plantation of cocoa tea can be set up to cultivate new varieties, and cocoa tea of different flavors such as green cocoa tea, oolong cocoa tea, and black cocoa tea can be processed. Thus, cocoa tea will become a choice in the tea market.     

Plasma and lipoprotein levels of tea catechins following repeated tea consumption

Epidemiological studies suggest that antioxidant flavonoids in tea may reduce the risk of cardiovascular disease, possibly via protection of low-density lipoproteins (LDL) against oxidation. However, the extent of absorption of tea flavonoids and their accumulation in LDL during regular consumption of tea is not clear. Therefore we investigated plasma and lipoprotein levels of catechins during tea consumption and the impact on LDL oxidizability ex vivo. Eighteen healthy adults consumed, in an incomplete balanced cross-over design, green tea, black tea, black tea with milk or water, one cup every 2 hr (eight cups/day) for three days. Blood samples were obtained in the mornings and evenings of each day. Plasma total catechin concentration was determined in all blood samples, and the distribution of catechins among lipoproteins was determined at the end of the third day (t = 60 hr). The resistance of LDL to copper-induced oxidation ex vivo was assessed before tea consumption and at t = 60 hr. Repeated tea consumption during the day rapidly increased plasma total catechin levels whereas they declined overnight when no tea was consumed. There was a gradual increase in plasma levels in the mornings (respectively, 0.08 microM vs. 0.20 microM on first and last day of black tea consumption) and evenings (respectively, 0.29 microM vs. 0.34 microM on first and last day of black tea consumption). Green tea catechins were mainly found in the protein-rich fraction of plasma (60%) and in high-density lipoproteins (23%). Although present in LDL, the concentration of catechins in LDL was not sufficient to enhance the resistance of LDL to oxidation ex vivo. Addition of milk to black tea did not affect any of the parameters measured. In conclusion, the present study shows that catechin levels in blood rapidly increase upon repeated tea consumption. The accumulation of catechins in LDL particles is not sufficient to improve the intrinsic resistance of LDL to oxidation ex vivo.     

茶多酚提取方法的研究进展

茶多酚是一种理想的食品天然抗氧化剂,具有抗癌治病、防衰老、防辐射、消除人体自由基等多种生理功效,广泛用于食品、油脂、医药、化工等行业。近年来,对于茶多酚的提取方法多见于报遗,本文就国内外茶多酚提取方法的研究进展情况作以综述。