三株散囊菌属真菌的茶叶液态发酵与其成分分析

散囊菌属真菌(Eurotium spp.)又称“金花菌”,能在六堡茶表面生长出金黄色的子囊果而得名,是一类对发酵茶叶的品质有积极影响的真菌。本研究前期从广西梧州六堡茶中筛选到的三株散囊菌属真菌Aspergillus chevalieri E2(简称E2),Aspergillus chevalieri E3(简称E3)与Aspergillus cristatus E6(简称E6),将菌株接种于自制液体茶粉培养基中培养,检测发酵液中产生的色素物质;测定发酵液中纤维素酶、果胶酶、淀粉酶的酶活力、总糖和还原糖糖含量、氨基酸含量、总抗氧化能力、自由基清除能力和茶多酚含量。结果表明:三株真菌在液体茶粉培养基中生长良好,E3生长尤其迅速。在8 d的培养期限内,E2、E3和E6的最高果胶酶活力分别为2.52、3.44和5.15 U/mL;最高纤维素酶活力分别为0.57、0.82和1.10 U/mL;最高淀粉酶活力分别为0.31、0.35和0.49 U/mL。三株真菌的发酵后培养液中还原糖含量大幅增加,增幅分别达到131.70%、627.02%和459.12%;总糖含量同样呈上升趋势,增幅分别达到6.84%、35.25%和2.07%;E2与E3的氨基酸含量分别下降了17.43%与32.68%,E6则上升了0.52%;E3的总抗氧化活性提升最大,达65.87%;DPPH·自由基清除能力提升最大的是E2,达128.33%;茶多酚含量都显著提升,增幅分别为50.85%、51.58%和53.06%。本研究对改善六堡茶的品质及茶叶的发酵的研究有一定意义和参考价值。

Liquid fermentation of tea by three Eurotium spp. fungi and their corresponding content analyses

Eurotium spp.,a type of golden-ascomata producing fungi that grow on its surface,hence named as“golden flower fungi”,have positive effects on the quality of the fermented tea.This research used three previously isolated Eurotium strains,Aspergillus chevalieri E2(E2),Aspergillus chevalieri E3(E3)and Aspergillus cristatus E6(E6).The strains were inoculated into the self-made liquid tea powder medium and cultured,the pigments produced during the culturing was examined;the enzyme activities of cellulase,pectinase and amylase were assayed;the total sugar content,reducing sugar content,the amino acids content,the total antioxidant activity,the free radicals removing abilities and the tea polyphenols content were measured.The result showed:three strains adapted well in the liquid tea powder medium,for which E3 had the quickest growth speed.In the 8 d culturing,the highest pectinase activities from E2,E3 and E6 were 2.52 U/mL,3.44 U/mL and 5.15 U/mL,respectively;the highest cellulase activities were 0.57 U/mL,0.82 U/mL and 1.10 U/mL,respectively;the highest amylase activities were 0.31 U/mL,0.35 U/mL and 0.49 U/mL,respectively.In the fermented liquids of three strains,the reducing sugar contents increased drastically,the increase percentages were 131.70%,627.02%and 459.12%,respectively;the total sugar contents also increased,the increase percentages were 6.84%,35.25%and 2.07%,respectively;the amino acids content of E2 and E3 dropped 17.43%and 32.68%respectively,while E6 rose 0.52%;for the total antioxidant activity,E3 had the sharpest increment of 65.87%;E2 had the sharpest increment of DPPH·free radicals removing activity,128.33%;the tea polyphenols contents rose by 50.85%,51.58%and 53.06%,respectively.This research had certain significance and referential value for the improvement of the Liupao tea and the tea fermentation.