Paper Chromatography and UV-Vis Spectroscopy To Characterize Anthocyanins and Investigate Antioxidant Properties in the Organic Teaching Laboratory

A variety of fruits and vegetables, including raspberries, blueberries, Concord grapes, blackberries, strawberries, peaches, eggplant, red cabbage, and red onions, contain flavonoid compounds known as anthocyanins that are responsible for the blue-red color and the astringent taste associated with such foods. In addition, anthocyanins exhibit a wide range of chemical properties, such as radical scavenging, metal chelation, pH-dependent color changes, and intramolecular stabilization. Two experiments have been developed for anthocyanin-containing extracts isolated from freeze-dried berries to teach students the skills of solid liquid extraction, paper chromatography, UV vis spectroscopic characterization, and detection and evaluation of radical scavenging properties.