Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/24/2007
Publication Date: 6/30/2007
Citation: Jham, G.N., Winkler, J.K., Berhow, M.A., Vaughn, S.F. 2007. Gamma-Tocopherol as a marker of Brazilian coffee (Coffea arabica L.) adulteration by corn. Journal of Agriculture and Food Chemistry. 55:5995-5999.
Interpretive Summary: Adulteration of coffee, a valuable commodity, is considered to be one of the most serious problems affecting coffee quality. Methods of detection are limited due to the highly complex chemical composition of coffee. Corn is considered to be one of the common adulterants of coffee used in Brazil. The profiles of various tocopherols (Vitamin E compounds) in several Brazilian coffee varieties, in commercial coffee samples and in six corn varieties were analyzed by high-performance liquid chromatography. This analysis demonstrated that there were significant differences in the tocopherol profile between coffee and corn. These differences could be applied to detect corn in a pure coffee sample intentionally contaminated with corn. With this methodology, one of the six popular commercial coffee brands evaluated was likely adulterated with 8.9% corn. Tocopherol fingerprinting offers potential to detect adulteration of coffee with corn or with other adulterants. In addition, the overall methodology of tocopherol fingerprinting may be useful for detecting adulteration in many types of commodities.
Technical Abstract: Percentages of alpha-, beta-, gamma-, and delta-tocopherol determined by high-performance liquid chromatography in six coffee varieties were 29.0, 61.7, 3.3, and 6.0, respectively. Similar values were obtained in six popular coffee brands. The percentages of alpha-, gamma- and delta-tocopherol in six corn samples were 3.6, 91.3, and 5.1, respectively. These differences could be applied to detect corn in a pure coffee sample intentionally contaminated with corn, with the best result obtained with gamma-tocopherol. With this methodology, one out of the six popular commercial coffee brands evaluated was likely adulterated with 8.9% corn. Tocopherol fingerprinting offers potential to detect adulteration.