Fungal Colonization of Pu‐erh Tea in Yunnan

Abstract

Pu-erh tea is a popular beverage in Southeast Asia, especially in many areas of China. Natural fungal inoculation and fermentation form its special quality and function in health care. At the same time, a common assumption is that unknown fungi from natural inoculation may pose a risk for safety of drinking the beverage, leading to an urgent need for a thorough fungal survey of Pu-erh tea. The present paper reports the natural fungal colonizations isolated from 60 representative samples. The results of the survey showed that the fungal colonizations were isolated from all the samples studied, ranging from 1.6 ¥ 10 3 to 1.16 ¥ 10 5 cfu/g, and 62 isolates were identified to belong to 41 species of 19 genera, including 13 species of Aspergillus and seven species of Penicillium, and 21 species of other genera. The predominant fungi were yeasts and different species of the genus Aspergillus. The concrete species of the dominant fungi varied with environment conditions of various production places. Sample parameters such as water content, A W , pH, polyphenol content were recorded, though they appeared to have no obvious effects on the total number of fungi, whereas processing and storage methods evidently affected total number of fungi. Some species of fungi such as Aspergillus fumigatus, Penicillium spp., Trichoderma spp. and Fusarium culmorum, etc., which maybe excrete toxic metabolites, were isolated in the survey. Further evaluation on the safety of these fungi isolated from Pu-erh tea products is needed. PRACTICAL APPLICATIONSThis study investigated the fungal colonizatins exisiting in Pu-erh tea and some parameters concerning the storage of Pu-erh tea. These findings will help 3 Corresponding

A preliminary metagenomic study of puer tea during pile fermentation

“…Most researchers think that fungi, including species of Aspergillus , Fusarium , Penicillium , Rhizomucor , Trichoderma , Cladosporium and Mucor , and yeasts are likely to be key players responsible for puer tea fermentation . In comparison with those previous research data, we found significantly lower percentages of Eukaryota in the present puer tea metagenomic analysis; instead, the dominant microbes were bacteria.…”

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

“…The number of fungi detected in both raw and ripened tea declined as the aging period increased (Figure ). The piling or fermentation of the ripened Pu'er tea before it is compressed into bricks may increase fungal multiplication (Zhao and others ). The decline in fungal numbers with aging may result from a decrease in water content (Peng and Yu ) or a limited availability of nutrients as the proportion of less accessible compounds and more recalcitrant compounds increases with decomposition.…”

“…Pu'er, a unique postfermented tea produced in China, has antiobesity, hypolipidemic, and antioxidative properties (Duh and others ; Chiang and others ; Jie and others ; Wu and others ; Mo and others ). Pu'er tea is now commonly consumed in Southeast Asia and western countries as raw tea (similar to green tea) or ripened (fermented) tea (Zhao and others ). The processing of raw tea includes sun fixation, rolling, and sun drying before the tea is compressed into tea bricks.…”

“…Although Pu'er tea has been produced, fermented, and consumed for hundreds of years, its microbiological properties are not been well understood (Mo and others ). Bacteria and fungi such as Aspergillus spp., Blastobotry adeninivorans , Penicillium spp., Trichoderma spp., and Fusarium culmorum are commonly detected during the fermenting process (Xu and others ; Abe and others ; Zhao and others ), and Aspergillus niger is the dominant fungus contributing to the production of volatile compounds during fermentation (Mo and others ; Xu and others ). Previous studies have reported that the fungal community is associated with the fermenting processes (Abe and others ), and the specific fungal strains have been isolated from Pu'er tea (Xu and others ).…”

Isolation, characterization and application of theophylline-degrading Aspergillus fungi

“…and Penicillium spp. are the filamentous fungal genera commonly associated with SSF of pu-erh tea [52][53][54], particularly A. niger, A. sydowii and A. tamarii having been widely reported as the dominant fungi in the SSF of pu-erh tea. The assessment in agar mediums with theophylline as carbon source showed that six Aspergillus isolates could survive in theophylline agar mediums, which suggested that those six candidate isolates (Table 3) could utilize theophylline as potential carbon source directly in the absence of other carbon source.…”