Optimization and modeling of the chlorogenic acid extraction from a residue of yerba mate processing

Abstract

Chlorogenic acid (CGA) and its hydrolysis products, quinic and caffeic acids are considered as fine chemicals and have a high commercial value. Yerba mate stems, useless residue from yerba mate processing, contains significant amounts of CGA. The goal of this study was to determine the best conditions for maximizing the CGA aqueous extraction from residues of yerba mate processing and to fit the extraction kinetics to empirical models. The effect of single factors such as solid-liquid ratio, numbers of extraction, temperature and time were studied for two particle sizes, using one factor at a time method and Response Surface Methodology (RSM). The highest and almost instantaneous CGA extraction (1.051 ± 0.015 gCGA L−1) was obtained using Ø particle size < 500 μm, at 65 °C, solid-liquid ratio of 1:20 and double stage extraction. For the largest particle size (2.5 × 5 mm > particle size >1 × 5 mm) the optimized conditions were 85 ± 5 °C and 25 ± 5 min, solid-liquid ratio of 1:20 and double stage extraction. For these last particles, the applied models of Pilosof et al. and Spiro and Jago showed a good agreement with the experimental and model calculated data. In the present study, it was possible to optimize the CGA extraction conditions for two particle sizes of yerba mate stems, in order to obtain extracts with high content of CGA that can be used in the production of others fine chemicals of interest in pharmaceutical industries.