TITLE:
Quality aspects of coffees and teas: Application of electron paramagnetic resonance (EPR) spectroscopy to the elucidation of free radical and other processes.
AUTHORS:
Bernard A. Goodman, Chahan Yeretzian, Klaus Stolze, Deng Wen
KEYWORDS:
Coffee; Tea; Free Radicals; Antioxidants; EPR Spectroscopy; Quality
JOURNAL NAME:
Agricultural Sciences,
Vol.4 No.8,
August
9,
2013
ABSTRACT: Coffees and teas are
beverages that are both exceptionally rich in antioxidant molecules, and are
also both associated with beneficial health effects. Thus although the quality
characteristics of these beverages are conventionally assessed on the basis
of their sensory properties, their antioxidant contents represent an additional
and increasingly valued attribute of quality based on their contributions to
healthy diets. Both beverages are
prepared by hot water extraction of a pure plant-derived product, and thus their
compositions can potentially change quite rapidly as a result of oxidation in
contact with air. Oxidative processes often proceed via free radical
intermediates, and sometimes also result in the formation of stable radical
end-products; thus EPR spectroscopy is a convenient technique for
investigating some of the various free radical reactions that occur in these
beverages. This paper reviews progress that has been made in elucidating free
radical processes that occur during the preparation and storage of coffees and
teas, and the results are discussed in terms of quality criteria of the
beverages.