FUNGAL COLONIZATION OF PU‐ERH TEA IN YUNNAN

Abstract

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 × 103 to 1.16 × 105 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, AW, 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 to evaluate the safety of Pu‐erh tea products, and also facilitate the formulation of microbiologically sound methods for the manufacture and storage of Pu‐erh tea, especially for the supervision of microbic fermentation during the process of ripe Pu‐erh tea manufacture, thus contributing to avoid the contamination from toxigenic or potentially toxic fungi, and to ensure the safety of drinking Pu‐erh tea.