THE USE OF CHEMICAL MARKERS AND MODEL STUDIES TO ASSESS THE IN VITRO PRO- AND ANTIOXIDATIVE PROPERTIES OF METHYLXANTHINE-RICH BEVERAGES

Abstract

Chemical markers and model studies are useful in predicting the stability and shelf life of foods and beverages in food technology and chemistry. Chemical modification induced by food processing has an impact on the reactivity and chemical properties of the food constituents, frequently giving rise to new molecules with enhanced antioxidative activity and potential health benefit. In the case of coffee, tea, and cocoa, these positive characteristics are often associated with dietary polyphenols. In particular, the often referred to “paradox” behavior of endogenous polyphenols to act as anti- and/or prooxidants is demonstrated with the aid of in vitro model studies. Furthermore, in-situ chemical markers such as 8-oxocaffeine are described in methylxanthine-rich beverages that reflect oxidative reactions. Such chemicals can be employed to help assess the impact of processing conditions on food quality as well as to predict the stability of the final product.

ACKNOWLEDGMENTS

The author thanks Dr. Miriam Richelle for valuable discussions and comments.

Notes

^*AC is defined as the inhibitory effect of various antioxidants on lipid peroxidation and calculated as follows: AC (%) = 100[(M_i − M_min)/(M_max − M_min)], where M_i corresponds to the TBARS formation at 30 min in the presence of antioxidant. M_max represents TBARS formation in the absence of antioxidants, and M_min corresponds to “background” peroxidation when lipid peroxidation is fully inhibited by the addition of EDTA and BHT.