Title
A comparative study of the antioxidant scavenging activity of green tea, black tea and coffee extracts: A kinetic approach
Author
Jaouad Anissi, Mohammed El Hassouni, Abdelkrim Ouardaoui, Khalid Sendide
Year
2013
Journal
Food Chemistry
Abstract
The antioxidant activities of three beverages, coffee, black tea and green tea, along with their major components, were investigated in terms of their reaction with the stable radical 2,2′-diphenyl-2-picrylhydrazyl (DPPHradical dot). We used a kinetic approach in parallel with quantification methods based on a fixed end-point to determine the scavenging efficiency of compounds abundant in these beverages during their reaction with DPPHradical dotusing a stopped-flow spectrophotometer-based method. Ascorbic acid, (+)-catechin, (−)-epigallocatechin, tannic acid, and caffeic acid were selected as model antioxidants to study in coffee, black tea and green tea. We applied a second-order model to demonstrate similarities in the kinetics behavior of beverages and related compounds. Our findings showed the slopes View the MathML source and View the MathML source exhibited similar and correlated values; we suggest the variation in View the MathML source as a function of time is more informative about antioxidant properties than reaction with DPPHradical dot alone. We also usedIC100 to test the reliability of the relative stoichiometry using a new comparative parameter “n ”, which was calculated as: View the MathML source (mol/L (mol/L)−1, (mol/L) ml mg−1 or mol g−1).
Instrument
J-815
Keywords
Circular dichroism, Food science