Analysis of caffeine and flavan-3-ol composition in the fresh leaf ofCamellia sinesis for predicting the quality of the black tea produced in Central and Southern Africa

Integrating satellite images and spectroscopy to measuring green and black tea quality

“…The formation of theaflavin requires a reaction between a trihydroxyflavan-3-ol and a dihydroxyflavan-3-ol (Nakagawa & Torii, 1965;Robertson, 1983). The correct balance and amount of the trihydroxyflavan-3-ols and dihydroxyflavan-3-ols are therefore necessary to ensure maximum formation of the theaflavins, one of the key chemical quality parameters of black tea (Deb & Ullah, 1968;Hilton & Ellis, 1972;Hilton & Palmer-Jones, 1975;Wright, Mphangwe, Nyirenda, & Apostolides, 2000;Wright et al, 2002). Although, in the two clones used in this study, their levels were higher, they could be the limiting factor in theaflavins formation as they run out faster.…”

Bioactive compound retention in Echium amoenum Fisch. & C. A. Mey. petals: Effect of fluidized bed drying conditions

“…[16,17] A mass concentration of 10 mg/mL of extract was mixed with 1.0 mL of Folin-Ciocalteu's reagent, 0.8 mL of Na 2 CO 3 was added and the volume was then increased to 10 mL using water/methanol (4:6) mixture as diluting fluid. Absorbance was read at 740 nm after 30 min using a UV/Vis spectrophotometer (type 108, Systronics, Ahmedabad, Gujarat, India).…”

Effects of extraction solvents on concentration and antioxidant activity of black and black mate tea polyphenols determined by ferrous tartrate and Folin–Ciocalteu methods

“…In addition, in this study two spectrophotometric methods based on different reactions were tested for determination of polyphenols. One is the Folin-Ciocalteu method widely used in routine analysis (Atoui et al, 2005;Wright, Mphangwe, Nyirenda, & Apostolides, 2000) and other is the method (Caffin, D Arcy, Yao, & Rintoul, 2004;Li, Wang, Ma, & Zhang, 2005;Liang et al, 2003) which has been used especially for analysis of tea polyphenols.…”