Using Capillary Electrophoresis to Quantify Organic Acids from Plant Tissue: A Test Case Examining <em>Coffea arabica</em> Seeds

Abstract

Carboxylic acids are organic acids containing one or more terminal carboxyl (COOH) functional groups. Short chain carboxylic acids (SCCAs; carboxylic acids containing three to six carbons), such as malate and citrate, are critical to the proper functioning of many biological systems, where they function in cellular respiration and can serve as indicators of cell health. In foods, organic acid content can have significant impact on taste, with increased SCCA levels resulting in a sour or "acid" taste. Because of this, methods for the rapid analysis of organic acid levels are of particular interest to the food and beverage industries. Unfortunately, however, most methods used for SCCA quantification are dependent on time-consuming protocols requiring the derivatization of samples with hazardous reagents, followed by costly chromatographic and/or mass spectrometric analyses. This method details an alternate method for the detection and quantification of organic acids from plant material and food samples using free zonal capillary electrophoresis (CZE), sometimes simply referred to as capillary electrophoresis (CE). CZE provides a cost-effective method for measuring SCCAs with a low limit of detection (0.005 mg/ml). This article details the extraction and quantification of SCCAs from plant samples. While the method provided focuses on measurement of SCCAs from coffee beans, the method provided can be applied to multiple plant-based food materials.

Recent advances in the application of capillary electromigration methods for food analysis and Foodomics

“…The optimal sheath liquid composition consisted on 70:30 isopropanol/water ( v/v ) containing 7.5 mmol/L acetic acid at a flow rate of 6 μL/min . Besides, CE‐UV has been employed for the determination of the organic acids composition and quantification of 31 wine samples and for the classification of 38 samples of commercial wine from four wine‐producing provinces of Argentina according to the grape variety applying the Tucker3 algorithm , as well as for the measure of the changes in organic acids levels in coffee seeds as function of different fermentation treatments . Moreover, CE has shown an interesting application as a tool for the downstream process monitoring by the detection of organic impurities in the process of lactic acid purification from 15‐s generation renewable feedstock .…”