| Green brick tea is a kind of tea which is mainly consumed by the minority who live in western China. Currently, more attentions have been paid in microbes in Fuzhuan other than microbes in green brick tea, Kangzhuan and other teas.In January,2007, we investigated microbes in 20 various samples such as the materials made in the process or in different stages of the process.156 fungal strains were obtained with a ration of 70.58%, together with 30 bacterial strains (13.57%),14 strains of yeasts (6.33%) and 21 strains of actinomycetes (9.50%). Meanwhile, methods such as plate diluting and colony counting were used to get the exact amount communities of microbes in each process stage. In summary, fungi in green brick tea were superior to bacteria, antinomies, yeasts in number. The fungal isolates from green brick tea were purified to investigate the population and importance.Morphological characteristics such as colony and the sizes of cleistothecia, ascus, ascospore, conidia were investigated for these 156 fungi strains. During the producing process of tea, ten types of fungi such as Aspergillus, Penicillium and other fungi species were check out. Aspergillus niger was dominant with a ratio of 57.8%, secondly, A. glaucus was with a ratio of 17.02%. Meanwhile, the morphologies and the sizes of cleistothecia, ascus, ascospore conidia and other fungi of Eurotium were found out too.Sequences of tubB and ITS of 16 strains including 5 type Eurotium strains and 11 strains isolated from different stages and places were analyzed. tubB and ITS squences among these isolates exhibited high similarities. In addition, phylogentic tree based on tubB and ITS sequences supported that the isolates were Eurotium cristatum.In order to investigate whether the fungi isolates play a role in the development of the quality of green brick tea or not, raw materials of green brick tea were inoculated with the fungal isolates and then incubated at 25℃for about 5 days. Through analyses of the content of water extracted, tea polyphenols, amino acids, caffeine and flavone glycosides, the role of the fungal isolates inoculated played was investigated. The content of caffeine was almost constant during the treatments, while other substances listed above decreased significantly. This was also observed on green brick tea. These indicated that the fragrance of green brick tea was possibly resulted by the fungi isolated. The resource and stability of yellow pigment were also investigated. Yellow pigment was successfully extracted from plates and liquid cultures of Eurotium cristatum through the method of organic solutions and supersonic waves. Furthermore, lights, temperatures and other factors influenced on this pigment were studied. The results showed that high temperatures affected yellow pigment's stability, and so do sunlight and UV. The yellow pigment was more stable in acidic condition. Many kinds of metal ions had different influences on this pigment. Phosphate affected the stabilization of the pigment greatly, while H2O2, NaHSO3 and citric acid destroyed it less obviously. Sodium benzoate's destruction against this pigment was stronger than potassium sorbate; EDTA-Na2 and Vc might protect the pigment because EDTA-Na2 might bind proteins that would, perhaps, disrupt the stability of the pigment. And, carbohydrates, sodium chloride, oxalate and lactic acid had no evident effect on the pigment. |
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