Quality aspects of coffees and teas: Application of electron paramagnetic resonance (EPR) spectroscopy to the elucidation of free radical and other processes.

Bernard A. Goodman, Chahan Yeretzian, Klaus Stolze, Deng Wen

Department of Physics, Guangxi University, Nanning, China.
Institute of Pharmacology and Toxicology, Dept. Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria.
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, China.
Zurich University of Applied Sciences, Institute of Chemistry and Biological Chemistry, W?denswil, Switzerland.

DOI: 10.4236/as.2013.48058                

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.

Keywords

Coffee; Tea; Free Radicals; Antioxidants; EPR Spectroscopy; Quality

Conflicts of Interest

The authors declare no conflicts of interest.

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