Preliminary Study for Yunnan Tea Fermentation

Abstract

A process for tea fermentation and fermented-type tea products are not widely known in Thailand.Technology for producing green tea and semi-fermented tea has been entirely imported and used withoutapplied fermentation technology. Therefore, Thai fermented tea traditionally produced without usingmodern processing finds inconsistent and low quality. This study on preliminary tea fermentation was anattempt to use starter culture isolated from Puerh tea of Yunnan Province, P.R. China. Among three fungalstrains, two white molds were selected after capably producing amylase, protease, lipase and pectinase.Two factors, i.e. temperature (25, 30, 37 oC) and initial moisture content (30, 40, 50 %) affecting teafermentation were investigated with 9 experiments designed by Taguchi method. The highest solublepolysaccharides (PS) and total soluble solid (TSS) contents, which are important variables of qualifyingfermented tea, were obtained with tea fermented at 30 oC and 30 % initial moisture content. Bothcalculated values from Taguchi model are fitting very well with those experimental results of 0.062 g PS/g dry tea and 0.38 g TSS/g dry tea, respectively. Tea extracts from 9 experiments found aroma and colorfairy acceptable with 70 test panels by sensory evaluation. However, taste and overall likeness of teaextract need to be further improved, as well as any additional physico-chemical factors affecting teaquality during tea fermentation, to develop a modern tea processing and to meet high approval of teaconsumers.

Keywords : Tea Fermentation / Puerh Tea / Starter Culture / Taguchi Method