Extraction of phenolic compounds from organic dried apples: comparison between conventional, microwave- and ultrasound-assisted extraction methods

Summary

The aim of this study was to compare a conventional assay with microwave- (MAE) and ultrasound- (UAE) assisted extraction methods on the extraction of phenolic compounds from organic dried apples by evaluating the content in catechin, epicatechin, chlorogenic acid and quercitrin. Samples from two apple varieties (Golden Rush and Topaz) were analyzed. Methanol/water (70:30, v/v) was selected as the solvent mixture for the phenolic compounds extractions. The High Performance Liquid Chromatography coupled to diode array detection (HPLC-DAD) were used for the identification and quantification of the respective phenolic compounds. Qualitative analysis revealed similar phenolic profiles in both apple varieties. Whatever extraction method is used, in both apple varieties chlorogenic acid and epicatechin were present in higher contents compared to catechin and quercitrin with chlorogenic acid being the major contributor. It was found a better extraction of chlorogenic acid, catechin and quercitrin (only for Topaz apple) using conventional process in comparison with MAE and UAE. A higher content of quercitrin was obtained with MAE and UAE compared to conventional method. The content of phenolic compounds in Golden Rush apple was higher than in Topaz apple. Results from this study indicated that conventional extraction can be a more efficient process than MAE and UAE for the extraction of phenolic compounds from organic dried apples.