Theaflavins analysis

There are four main theaflavins common to black teas, and a second group of minor theaflavins, including the isotheaflavins (55) and neotheaflavins (57) (Table 5). The total theaflavin concentration in black tea leaves does not usually exceed 2% and can be as low as 0.3%. At most, only 10% of the catechins in tea flush can be accounted for as theaflavins in black tea and the fate of the remaining catechins is less clear. Theaflavins can be readily determined by direct hplc analysis of tea beverages (48,58,59). 

LEE B L and ONG c N (2000) Comparative analysis of tea catechins and theaflavins by high-performance liquid chromatography and capillary electrophoresis , J Chromatog A, 881 (1-2), 439-47. 

RP-HPLC has also been used for the analysis of flavan-3-ols and theaflavins during the study of the oxidation of flavan-3-ols in an immobilized enzyme system. Powdered tea leaves (20Qmg) were extracted with 3 X 5 ml of 70 per cent aqueous methanol at 70°C for lQmin. The combined supernatants were filtered and used for HPLC analysis. Flavan-3-ols were separated in a phenyl hexyl column (250 X 4.6 mm i.d. particle size 5 /im) at 30°C. Solvents A and B were 2 per cent acetic acid in ACN and 2 per cent acetic acid in water, respectively. Gradient elution was 0-lQmin, 95 per cent B 10-4Qmin, to 82 per cent B to 40-5Qmin 82 per cent B. The flow rate was 1 ml/min. Theaflavins were determined in an ODS column (100 X 4.6 mm i.d. particle size 3pm) at 30°C. The flow rate was 1.8 ml/min and solvent B was the isocratic mobile phase. The data demonstrated that flavan-3-ols disappear during the oxidation process while the amount of theaflavins with different chemical structures increases [177],... 

Menet, M.C. et al., Analysis of theaflavins and thearubigins from black tea extract by MALDI-TOF mass spectrometry, J. Agric. Food Chem., 52, 2455, 2004. 

Mulder, T.P., van Platerink, C.J., Wijnand Schuyl, P.J., and van Amelsvoort, J.M., Analysis of theaflavins in biological fluids using liquid chromatography-electrospray mass spectrometry, J. Chromatogr. B Biomed. Sci. AppL, 760, 271, 2001. 

Flavan-3-ols are key precursors of the quality-determining black tea pigments known as theaflavins, theafulvins, and thearubigins (139). The stability of major theaflavins (theaflavin, theaflavin-3-gallate, theaflavin-3 -gallate, theaflavin-3, 3 -digallate) during automated HPLC analysis was also evaluated due to the concern about the instability of aqueous extract of black... 

CM Temple, MN Clifford. The stability of theaflavins during HPLC analysis of a decaffeinated aqueous tea extract. J Sci Food Agric 74 536-540, 1997. 

Robertson, A. and Bendall, D. S. 1983. Production and HPLC analysis of black tea theaflavins and thearubigins during in vitro oxidation. Phytochemistry 22 883-87. 

Wright, L. R, Mphangwe, N. I. K., Nyirenda, H. E., and Apostolides, Z. 2002. Analysis of the theaflavin composition in black tea Camellia sinensis) for predicting the quality of tea produced in Central and Southern Africa. J. Sci. Food Agric. 82 517-25. 

Friedman, M., Levin, C. E., Choi, S. H., Kozukue, E., and Kozukue, N. 2006. HPLC analysis of catechins, theaflavins, and alkaloids in commercial teas and green tea dietary supplements Comparison of water and 80% ethanol/water extracts. J. Food Sci. 7LC328-37. 

Chen, C. W., Chang, Y. W., and Hwang, L. S. 1998. Rapid analysis of theaflavins by high performance liquid chromatography atmospheric pressure chemical ionization mass spectrometry. 7. Food Drug Anal. 6 713-18. 

As an example, the results obtained by E-Vision studies on tea liquor colour coupled with chemical analysis may assist remarkably the E-Tongue and E-Nose studies/developments. As discussed earlier, golden yellow coloured Theaflavins and... 

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