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Yunnan Pu-erh Tea
Abstract
For quite a long time, all the authoritative tea books and dictionaries list Pu-erh tea into category of brick tea. Pu-erh tea is made from the sun dried green tea, and then is fermented into remanufactured tea with significant differences in form and quality. According to theoretical tea classification, Pu-erh tea should be listed as one specific category, Pu-erh tea.
The fermentation course is slow naturally in traditional Pu-erh tea, the modernization of the process lies in the acceleration of the course of fermentation in the so-termed new craft Pu-erh tea. Through work in product development, both traditional and new craft are said to possess the similar quality characteristics.
In conclusion, Pu-erh tea should not be classified as a brick tea, but should belong to the post-fermented tea, which is a type of reprocessed tea.
... A dozen fungi, including Aspergillus, Penicillium and Eurotium, had been identified from CDTs using culture-dependent method or denaturing gradient gel electrophoresis (DGGE) technology [5,8]. Some of these microorganisms are known to secrete some enzymes such as hydrolases, which may promote tea fermentation [16,17]. In contrast to the knowledge about the fungal community of CDTs, little, if anything, is known about the composition of bacterial community in CDTs. ...
Chinese dark teas (CDTs) are now among the popular tea beverages worldwide due to their unique health benefits. Because the production of CDTs involves fermentation that is characterized by the effect of microbes, microorganisms are believed to play critical roles in the determination of the chemical characteristics of CDTs. Some dominant fungi have been identified from CDTs. In contrast, little, if anything, is known about the composition of bacterial community in CDTs. This study was set to investigate the diversity and variation of bacterial community in four major types of CDTs from China. First, the composition of the bacterial community of CDTs was determined using MiSeq sequencing. From the four typical CDTs, a total of 238 genera that belong to 128 families of bacteria were detected, including most of the families of beneficial bacteria known to be associated with fermented food. While different types of CDTs had generally distinct bacterial structures, the two types of brick teas produced from adjacent regions displayed strong similarity in bacterial composition, suggesting that the producing environment and processing condition perhaps together influence bacterial succession in CDTs. The global characterization of bacterial communities in CDTs is an essential first step for us to understand their function in fermentation and their potential impact on human health. Such knowledge will be important guidance for improving the production of CDTs with higher quality and elevated health benefits.
Pu-erh tea is a unique microbial fermented tea produced from the sun-dried leaves of large-leaf tea species (Camellia sinensis (Linn.) var. assamica (Masters) Kitamura) in the Yunnan province of China. Pu-erh tea has become increasingly popular in Southeast Asia may be due to its multiple health benefits. The special sensory characteristics of Pu-erh tea arise from the multitudinous chemical changes and transformations of the chemical constituents of the sun-dried green tea leaves that occur during the post-fermentation process. Many functional components have been isolated from Pu-erh tea and identified. In this paper, modern processing techniques and their effects on the transformation of the chemical constituents and the major chemical components of Pu-erh tea are reviewed and discussed.
Samples of Haipao from three cities of Taiwan were analyzed for their microbial population. Two species of acetic acid bacteria and three species of yeast were isolated from tea fungus Haipao using appropriate isolation media. The isolated bacteria were identified asAcetobacter acetiandAcetobacter pasteurianus, based on their biochemical properties, and compared with those of the type strains of the genusAcetobacter. The yeasts wereSaccharomyces cerevisiae, Zygosaccharomyces bailii, andBrettanomyces bruxellensisaccording to conventional phenotypic characterization combined with the Yeast Identification Program. The brew broth analyzed by high−performance liquid chromatography (HPLC) was shown to contain glycerol, acetic acid and ethanol. The symbiosis phenomenon between the yeast andAcetobacterwas studied. It was found that the autoclaved yeast cells and ethanol produced by yeasts were helpful forAcetobacterto grow or produce acetic acid. The acetic acid produced byAcetobactercould stimulate the yeast to produce ethanol. The ethanol and acetic acid produced by yeasts andAcetobactermight prevent the competition from other micro-organisms.
Two commercial Pu-erh teas, 15-year-old Ta-Huang-In and 25-year-old Ta-Hon-In, were used for screening some species of fungi, yeasts, and bacteria, and six of them were isolated and identified as Actinoplanes aurantiacus, Actinoplanes pallidoaurantiacus, Actinoplanes purpeobrunneus, Streptomyces bacillaris, Streptomyces cavourensis subsp. cavourensis, and Streptomyces cinereus. They were selected for inoculated into the tea leaves (Yun Nan from China, TTES-12 and C. S. Oolong from Taiwan) and fermented for 180 days. The total polyphenols and GABA content, and DPPH radical scavenging effects were determined to examine the tea infusion quality. The samples inoculated with S. cinereus had the highest total polyphenols content and maximum capacity to scavenge DPPH radicals; the highest GABA content was obtained while the sample inoculated with S. bacillaris. Further comparison of these samples with two commercial Pu-erh teas of different ages (Ta-Huang-In, 15-year storage and Ta-Hon-In, 25-year storage) showed that DPPH radical scavenging activity and GABA content of S. bacillaris and S. cinereus fermented tea leaf were higher than these two commercial teas. Sensory evaluation also demonstrated that the taste, flavor, and overall acceptance did not had significant differences between the experimental tea leaves and commercial samples. The present studies revealed that the fresh tea leaves inoculated with the suitable microbes in short period of time will possess a high-quality tea infusion as long-term storage Pu-erh tea.
Pu'er brick tea and Bianxiao brick tea are both compressed types of tea. Fluorine analysis was carried out on samples of Pu'er brick tea produced at different times in Yunnan Province and on samples of Bianxiao brick tea made in Hunan and Sichuan Province for supply especially to minority ethnic groups in border areas of China. The levels of water-soluble and water-insoluble fluorine were measured in the tea samples using an ion-specific electrode potentiometer. The concentration of water-soluble fluorine was much greater in Bianxiao brick tea than in Pu'er brick tea (mean levels 441 and 77 mg/kg, respectively). According to these figures, the fluorine intake associated with consuming an infusion of 30 g Pu'er brick tea/person/day is safe because it does not exceed the maximum recommended daily allowance (RDA) of up to 4.0 mg for adults. In contrast, the almost six times higher intake of fluorine from Bianxiao brick tea greatly exceeds the 4 mg RDA and is unsafe. The difference in the fluorine levels of the two types of brick tea can be attributed to differences in the materials used to make them: Pu'er brick tea is made from tender leaves whereas Bianxiao brick tea is made from old tough leaves in which fluorine has accumulated. We conclude that consumption of Pu'er brick tea is unlikely to induce fluorosis, which has been associated with consumption of Bianxiao brick tea.
Bacillus subtilis, Escherichia coli, Proteus vulgaris, Pseudomonas fluorescens, Salmonella sp. and Staphylococcus aureus were used to test the antimicrobial activity of tea flush extract and extracts of various tea products. Among the six test organisms, P. fluorescens was the most sensitive to the extracts, while B. subtilis was the least sensitive. In general, antimicrobial activity decreased when the extents of tea fermentation increased. The antimicrobial activities of tea flush extract and extracts of tea products with different extents of fermentation varied with test organisms. Tea flush and Green tea, the unfermented tea, exerted the strongest antimicrobial activity followed by the partially fermented tea products such as Longjing, Tieh-Kuan-Ying, Paochung, and Oolong teas. On the other hand, Black tea, the completely fermented tea, showed the least antimicrobial activity. It was also noted that extracts of Oolong tea prepared in summer exhibited the strongest antimicrobial activity, followed by those prepared in spring, winter and fall.
China is the only country that produces brick tea, and more than 90% of the brick tea is consumed in the western minority nationality regions of China. The high fluorine content of brick tea is possibly associated with the special processing procedures, but no investigation has been conducted in this field. To explore the characteristic features of brick tea manufacturing and the alterations in fluorine content during the processing procedures, we performed a field survey involving two brick tea factories and the nearby tea plantations. For the fluorine contents of the initial, intermediate and final processing products, altogether eight types of specimens were collected and determined by using the ion-selective electrode standard curve technique. It was found that the raw material tea leaf for brick tea processing was old, coarse and not the tender delicate tea leaf used for ordinary green or black tea processing. For the fluorine content of the raw material tea leaf, the intermediate and the final products showed that the fresh raw leaf contained a fluorine content as high as 489.31-512.68 mg/kg. During one fermentation-like processing procedure, the fluorine content rose by 4.67% and 1.88% in the specimens from the two factories, respectively, which revealed no statistical significance (P>0.5). These results suggest that the high fluorine content in brick tea might be due to the high content in the raw material and not related with the processing procedures.