Analysis and Identification of Major Organic Acids in Wine and Fruit Juices by Paper Chromatography

A simple and inexpensive paper chromatography experiment that separates and identifies major organic acids in wine and fruit juices has been developed for introductory organic undergraduate students to teach the basics of chromatography. This experiment reinforces several concepts for students such as compound separation via extraction and chromatography, intermolecular forces and acidity, and a comparison of organic acid polarities related to structure. In addition, the separation of acids within wine and/or fruit juices enhances student understanding of real-world organic acids present in foods. Citric, malic, tartaric, and lactic acids, all potential components of fruit juices and wine samples, are the focus of this experiment that includes a description of the malolactic fermentation occurring in wine samples. A mobile phase mixture of n-butanol, formic acid, acetone, and ethanol along with bromocresol green indicator allows for fast separation and visualization of the acids of interest. Retention fac...