Study On The Ferulic Acid And Its Antioxidation In The Fermented Tea

Fermented tea is one of the Chinese traditional tea with distinctive local features. The unique favor is particularly popular with people. This paper focuses on the ferulic acid and the antioxidation in the fermented tea. Results are as follows.1. Liquid chromatography was applied to determine the ferulic acid content. The chromatographic condition of this method is the chromatographic column of Shimpack VP-ODS C18(150mm×6mm,5μm). Mobile phase is 0.2% glacial acetic acid-100%carbinol (28:72); determine wavelength is 314nm; column tempeture is 30℃,flow velocity is 1.0 mL/min. The ferulic acid content measured in this condition was between 20～100μg/mL with good liner(correlation coefficient R2=0.9995). The average recovery rate was 98.73%; RSD was 1.71%. The ferulic acid content in the fermented tea of nine manufactures was in the range of 22.559-30.286μg/g, among which the Fuzhuan tea of Yiyang, Hunan was the highest, with the content of 30.286 μg/g.2. The screening of bacterial strain producing feruloyl esterase and the optimization of enzyme-producing conditions. A strain of active bacterial strain was selected after preliminary screening and secondary screening, and it was defined as the eurotium cristatum according to the form and the strain characteristics. Taking the enzyme activity of feruloyl esterase as measurement index, taking the moisture content of the tea, incolulum size, fermentation temperature and incubation time as the unit factor variable, the enzyme-producing conditions of the solid state fermentation of raw dark green tea was optimized. Results showed that in the test of solid state fermentation of raw dark green tea, the moisture content was 26%; inoculums size was 1‰ (amount of spore was 108CFU/g). The enzyme activity could be up to 142mU when incubated in 30℃ for 4 days.3. The optimization of the extraction process of ferulic acid in the fermented tea. The extraction process was optimized by RMS with 4 factors 3 levels. Results were that digesting the 8% sodium hydroxide with 100% methanol solution with the volume ratio of 1.35:1, combined with the ultrasonic temperature of 60℃, making the ferulic acid in the tea dissociate out, adjusting the pH of the leach liquor to 4 and being extracted by ethyl acetate, and then measuring the ferulic acid content with HPLC, the extraction capacity could be 44.79μg/g in this condition.4. Measurement of the antioxidant ability of the ferulic acid in the fermented tea. In the test, optimized extraction condition was used to measure the ferulic acid content of 11 samples, among which the content in the fermented tea with optimized process and the Xiangyi Fuzhuan Tea were the highest, up to 44.8742μg/g and 42.0651μg/g respectively. Three measurement methods--ABTS, DPPH and FRAP were applied to determine the antioxidant abilities of different fermented tea and raw dark green tea included in 11 tea samples. Results showed that the fermented tea with optimized process has the strongest antioxidant ability, followed by Xiangyi Fuzhan Tea. It can be concluded that the higher the ferulic acid content is, the stronger the antioxidant ability will be, which further indicates that the extracted ferulic acid from the fermented tea is with strong antioxidation, and its content is positively associated with the antioxidant ability of the tea.