| According to the previous studies on the processing and healthy functions of dark tea, in the present experiments, a method for determining ten organic acids simultaneously by high liquid chromatograph was investigated firstly, then the changes of main chemical components of Fuzhuan brick tea during the processing were analyzed. After that, the actions of the chemical components in Fuzhuan brick tea on the pancreatin activities were studied too. The main results were showed as follows:First, the analysis conditions for 10 kinds of organic acids (Oxilic acid, Pyruvate, D-malic acid, a-keto-glutaric acid, Ascorbic acid, Lactic acid, Acetic acid, Citric acid, L-malic acid, and Succinic acid) in the Fuzhuan brick tea were analyzed simultaneously using a Shimadzu LC-2010 HPLC equipped with a Diamonsil C18 column (4.6 x 250 mm, 5 μm particle size) and a UV detector. Wave length was set at 210 nm. Mobile phase was 0.1 mol/L KH2PO4 (pH value was adjusted to 2.8 by phosphoric acid). The flow rate was 0.6 mL/min and 15 μL sample was injected into the column. The column temperature was 30 ℃. The recoveries of the spiked organic acids and the relative standard deviations of the organic acids were 92.5% ~ 1013%, and 0.62%~2.73%, respectively. All of the correlation coefficients between the concentration of the organic acids and the HPLC response areas were higher than 0.94, which indicated that the method was simple, rapid and accurate.Second, five samples were collected from the major processing of Fuzhuan tea, including the raw materials, piling tea sample, fungus-growing tea sample, drying sample and made tea. The changes of the main chemical components including tea polyphenol, protein, amino acid, catechins, water extracts, tea polysaccharide and organic acids in the five processing were measured. The contents of amino acid, protein, tea polyphenols, catechins and caffeine were 29.86 mg/g, 22.05 mg/g, 82.82 mg/g, 39.76 mg/g and 8.52mg/g respectively in the piling processing, and decreased to 24.38 mg/g, 20.95 mg/g, 70.16 mg/g, 33.42 mg/g and 8.06 mg/g after 5 days' fungus-growing separately. The contents of tea polysaccharide and the organic acidchanged significantly in the fungus-growing processing, the contents changed from 74.74 mg/g, 42.63 mg/g to 63.98 mg/g, 52.03 mg/g, respectively. We suggested that the temperature and humidity in the steaming, piling and the pressing processing and the fungus in the fermenting processing effected on the quality of the Fuzhuan brick tea.Third, the chemical compositions in the processing of the Fuzhuan brick tea and their activation to the pancreatin were analyzed, the results indicated that the Fuzhuan brick tea had a good activation to the pancreatic amlyase and protease, however, no effect on the pancreatic lipase. The activation reflection value was defined as the activation rate in each gram of the dry tea. The parameters correlating significantly with the activation reflection value were classified into two groups. Group 1 was polyphenols, group 2 organic acids. For constructing regression equations two principal components were screened from the two groups as independent variables, it was easy to estimate the activation reflection value by principal component analysis. The results showed that the contents of total catechins and L-malic acid had a highly significant relationship with the activation reflection value of the pancreatic amlyase, and the contents of total catechins and oxalic acid had a significant relationship with the activation reflection value of the pancreatic protease. The equations were: The activation reflection value (amylase) = 23.025+0.572 TC +0.742 L—malic acid;The activation reflection value (protease) = 10.192+0.386 TC+4.189 Oxilic acid. Therefore, we suggested that the catechins and organic acids in the brick tea had positive actions on the protein and starch digestion for human being, whatever, to drink Fuzhuan brick tea is no effect on the absorbance of lipid in the dairy life.
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