Related Experiment Video
Updated: Jun 23, 2025

Using Capillary Electrophoresis to Quantify Organic Acids from Plant Tissue: A Test Case Examining Coffea arabica Seeds
Published on: November 12, 2016
Alterations in pH of Coffee Bean Extract and Properties of Chlorogenic Acid Based on the Roasting Degree
Yi Kyeoung Kim1, Jae-Min Lim2, Young Jae Kim3
1Department of Plant Biotechnology, Korea University, Seoul 02841, Republic of Korea.
Abstract:
Factors influencing the sour taste of coffee and the properties of chlorogenic acid are not yet fully understood. This study aimed to evaluate the impact of roasting degree on pH-associated changes in coffee bean extract and the thermal stability of chlorogenic acid. Coffee bean extract pH decreased up to a chromaticity value of 75 but increased with higher chromaticity values. Ultraviolet-visible spectrophotometry and structural analysis attributed this effect to chlorogenic and caffeic acids. Moreover, liquid chromatography-mass spectrometry analysis identified four chlorogenic acid types in green coffee bean extract. Chlorogenic acid isomers were eluted broadly on HPLC, and a chlorogenic acid fraction graph with two peaks, fractions 5 and 9, was obtained. Among the various fractions, the isomer in fraction 5 had significantly lower thermal stability, indicating that thermal stability differs between chlorogenic acid isomers.
More Related Videos
Related Concept Videos
Extraction: Effects of pH
pH
Substituent Effects on Acidity of Carboxylic Acids
Loss of Carboxy Group as CO2: Decarboxylation of Malonic Acid Derivatives
Mixtures of Acids
A Mixture of a Strong Acid and a Weak Acid
In a mixture of a strong acid and a weak acid, the strong acid dissociates completely and becomes a source of almost all the hydronium ions...
Loss of Carboxy Group as CO2: Decarboxylation of β-Ketoacids

