三株散囊菌发酵茶叶的初步研究

散囊菌属真菌(Eurotium spp.)能赋予发酵茶独特的口感和香味。本研究利用前期从广西某六堡茶中筛选并鉴定的三株散囊菌属真菌Aspergillus chevalieri E2、Aspergillus chevalieri E3与Aspergillus cristatus E6,探讨在不同温度下以优化察氏液体培养基培养的生长状况,发酵前不同灭菌条件下的茶叶品质,以及所得茶汤中茶多酚含量、总抗氧化能力和DPPH·自由基清除能力。结果显示:三株真菌在优化的察氏液体培养基中31℃～34℃下都能良好生长。茶叶发酵温度为28℃,三株真菌在发酵初始含水量为20%以上生长良好,其中E3和混合发酵组的生长速度最快。E2在茶叶表面生长出大量金黄色子囊果以及大量浅绿色分生孢子梗; E3几乎只有浅绿色分生孢子梗; E6几乎只有金黄色子囊果。发酵茶叶制作的茶汤内茶多酚含量比未发酵低,抗氧化性指标也有所下降,说明本实验真菌发酵促进了茶内抗氧化物质的氧化。本研究对源于六堡茶不同散囊菌属真菌的茶叶发酵有重要参考价值。

Preliminary study on fermentation of tea by three Eurotium spp. fungi

The Eurotium spp.can give special flavor and aroma to the fermented tea.In this research three Eurotium spp.fungi Aspergillus chevalieri E2(E2),Aspergillus chevalieri E3(E3)and Aspergillus cristatus E6(E6)were used,which were previously isolated and identified from the Liupao tea produced in Guangxi.The experiments were conducted including their growth conditions on optimized liquid Czapek medium at different temperature,the quality analysis of tea under different sterilization methods before being fermented by these fungi,the polyphenols content,the total antioxidant capacity and the DPPH·free radical scavenging ability of their tea soup.The results showed that the growth conditions for three fungi were good in optimized liquid Czapek medium at 31℃~34℃.When the temperature for tea fermentation was at 28℃,three fungi grew well with the initial fermentation water content more than or equal to 20%.Among them,E2 set and hybrid fermentation set had the fastest growth speed.On the surface of the tea leaves,E2 produced large amount of golden ascocarp and olivine conidiophores;E3 nearly just produced olivine conidiophores;and E6 almost only produced golden ascocarp.The content of polyphenols in fermented tea soup was lower than that in unfermented tea soup and their antioxidative indexe was also decreased,this explained the fermentation accelerated the oxidation of antioxidants in tea.This research had an important reference value to the fermentation of tea by different Eurotium fungi from Liupao tea.