基质水活度对冠突散囊菌生物转化茶叶成分的影响

Effects of Substrate Water Activity on Tea Components by Eurotium cristatum Biotransformation

为茯砖茶的加工及质量控制提供参考,以甘油调节培养基的水活度(aw),参照国家标准分析水活度对冠突散囊菌发酵后游离氨基酸、可溶性糖和茶多酚代谢的影响;并采用顶空固相微萃取和GC-MS相结合,分析不同基质水活度条件下真菌发酵后茶叶香气成分的变化。结果表明:冠突散囊菌在低水活度下生长良好,基质水活度为0.95时生物量最大,为0.258g;冠突散囊菌发酵10d后,不同水活度条件下,发酵液中可溶性糖、氨基酸和茶多酚的含量差异明显;在水活度为0.99~0.83,随着培养基水活度的进一步降低,发酵液中可溶性糖、氨基酸和茶多酚的含量逐渐上升;培养基水活度明显影响发酵液香气物质种类及其含量,随着基质水活度下降,冠突散囊菌发酵后茶叶香气化合物总数和各类物质相对含量均呈下降趋势。基质水活度是冠突散囊菌发酵绿茶过程中重要的影响因子,对发酵液品质成分和香气物质有显著的调控作用,实际应用中,基质水活度控制在0.95比较合适。

The effects of substrate water activity(a w)on free amino acids,soluble sugar and tea polyphenol content of the fermented Eurotium cristatum broth were analyzed under different substrate a w condition by adding glycerinum according to the national standard analysis method and the aroma components of fermented Fuzhuan Brick Tea were detected by headspace solid phase microextraction and GC-MS methods under different substrate a w condition to provide a reference for processing and quality control of Fuzhuan Brick Tea.Result:E.cristatum grows well under low a w and the biomass reaches 0.258 g(the maximum)when the substrate a w is 0.95.There is an obvious significance in content of soluble sugar,amino acid and tea polyphenol in the E.cristatum broth after 10 d fermentation under different a w condition.The content of soluble sugar,amino acid and tea polyphenol in the fermented E.cristatum broth rises gradually with reduction of the substrate a w within 0.99-0.83.The substrate a w has the effects on kind and content of aroma substance in the fermented E.cristatum broth and the relative content of total aroma’compounds and various substances in Fuzhuan Brick Tea after E.cristatum fermentation shows a declining trend with reduction of substrate a w.The substrate a w is the important influencing factor during the E.cristatum fermentation process of Fuzhuan Brick Tea and has the significant regulating effects on quality components and aroma substances of the fermented E.cristatum broth.The suitable substrate a w should be controlled at 0.95 in practical application.