Journal
FOOD CHEMISTRY
Volume 150, Issue -, Pages 438-447Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.foodchem.2013.11.009
Keywords
DPPFI* free-radical; Kinetic behavior; Second-order model; Green tea; Black tea; Coffee; DPPFI* scavenging efficiency comparison
Funding
- Al Akhawayn University in Ifrane University's seed Research Fund
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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'-dipheny1-2-picrylhydrazyl (DPPI-1(.)). 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 DPPH. using 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 K-2'((mol/L)(-1) s(-1)) and K-max ((mol/L)(-1) s(-1)) exhibited similar and correlated values; we suggest the variation in k(2)' as a function of time is more informative about antioxidant properties than reaction with DPPH. alone. We also used IC100 to test the reliability of the relative stoichiometry using a new comparative parameter n, which was calculated as: n = coDPPH/IC100 (mol/L (mol/L)(-1), (mol/L) ml mg(-1) or mol g(-1) (C) 2013 Elsevier Ltd. All rights reserved.
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