EFFECTS OF BACTERIAL STRAINS ON SENSORY QUALITY OF PU-ERH TEA IN AN IMPROVED PILE-FERMENTATION PROCESS

The aim of this study was to evaluate the sensory quality differences between microbe-inoculated and noninoculated tea infusions. Fifteen strains isolate from samples of the 15-year Ta-Huang-In and 25-year Ta-Hon-In of Pu-erh tea were inoculated into the tea leaves and then an improved pile-fermentation process under 60-70% relative humidity at 37C for 42 days was commenced. The results showed that there were significant effects on tea infusion mustiness, floral aroma, caramelness, sweetness, grassiness, fullness and sweet aftertaste. The sensory evaluation of odor, flavor and aftertaste of tea infusions inoculated with strains R8, R9, R15, Y11 and Y21 achieved higher scores than that of the blank. Thus, these strains governed the better performance in the overall acceptability of tea infusion. This was also demonstrated in the principal component analysis score plot. Furthermore, the tea infusion color of inoculated samples was similar to the commercial Pu-erh tea product. By this indicated way of using isolated microbe with shortened fermentation time (6 weeks), the sensory quality of tea infusions may be the same as that of old commercial Pu-erh tea. PRACTICAL APPLICATIONS In this report, we studied the effects of isolated microbes on the sensory quality (i.e., mustiness, floral aroma, caramelness, sweetness, grassiness, fullness and sweet aftertaste) differences between microbe inoculated and non-inoculated tea infusions for Pu-erh tea in an improved pile-fermentation process. By using the results from this study, the tea infusion color of inoculating sample was also similar to the commercial Pu-erh tea product. By this indicated way of using isolated microbe with shortened the fermentation time (6 weeks), the sensory quality of tea infusion may be the same as that of old commercial Pu-erh tea. What is crucial in this study is isolation of useful strains that governed a remarkable action in improving tea-leaf quality in a pile-fermentation process. The results of the research developed herein could effectively reduce fermentation time and could be suitably applied to the field of tea technology for large-scale commercial purposes.