The Rate of Decolorization of a Radical Ion Reagent Was Used to Determine the Phenolic Content of Various Food Extracts

Polyphenols are among the most valuable and widely studied food components. In the laboratory, they are readily extractable with aqueous alcohol. An aliquot rapidly decolorizes a measured portion of ABTS, a stable deep blue radical ion. The semilog plot of light absorption versus time is typically a straight line, and an immediately evident slope provides rapid classification in terms of gallic acid equivalents. Experimental data are presented to show general agreement with the literature. The disproportionate concentration of antioxidant in the skins and peels of fruits, vegetables, and nuts is given special attention. 1. Introduction Despite our efforts to keep fit, eat sensibly, and avoid accidents, we inevitably succumb to age-related diseases. Cells cannot reproduce indefinitely, presumably due to the unavoidable accumulation of DNA errors. To achieve longevity, we are urged (among many other precautions) to avoid ionizing radiation and choose foods that neutralize free radicals. These “antioxidants” represent a new positive note in advertising. They are touted on the labels of fruit juices and green tea, and they are improving the image of dark chocolate. Cosmetic manufacturers have put these beneficial ingredients in hair conditioners and wrinkle creams. Do antioxidants really neutralize the free radicals that kill cells and shorten life span? A skeptic might suggest that thousands of transient free radicals are present in every living cell at all times due to normal chemical activity. Nevertheless, determining which foods provide antioxidant activity, and to what extent, is an important current concern in the field of nutrition. A parallel development has been an increasing interest in a class of food chemicals that contain multiple hydroxyl groups on the same aromatic ring. They are referred to as polyphenols (or “phenolics”) and have gained a reputation for promoting health [1]. Polyphenols are radical scavengers and are often assumed to be responsible for antioxidant activity (AOA) in food. The theory is persuasive. When a phenolic hydrogen is removed, the extra electron would be shared around the aromatic ring—especially if there are other electrophilic substituents—and thereafter be rendered a spent force. However, not all investigators are comfortable identifying AOA with polyphenols, and some reports avoid this sideline aspect. Without necessarily claiming that they prevent cell damage, it is still reasonable to urge the consumption of foods that neutralize free radicals (and, by extension, peroxides). As it happens, this property also