Determination of polyphenols in the pear pulp matrix by solvent extraction and liquid chromatography with UV-Vis detection

Abstract

A new analytical method for the determination of polyphenolic compounds in pear pulp was developed here. The procedure consisted of solvent extraction for the recovery of analytes and further quantification by reversed-phase high-performance liquid chromatography with multidetection by UV-Vis molecular absorption spectroscopy. Preliminary studies were focused on establishing a straightforward extraction procedure for soluble compounds using organic and hydro-organic media. Dimethylsulfoxide was selected as the most efficient extraction solvent for the diverse polyphenol families. The chromatographic separation relied on a methanol gradient which was optimized by experimental design. Figures of merit were established under the selected experimental conditions using synthetic standards and pear extracts. In general, repeatabilities of peak areas were better than 3%, detection limits were in the order of magnitude of 0.1 mg L⁻¹ and quantitative recoveries were about 100%. The method was applied to analyze commercial pears of various origins with chlorogenic, neochlorogenic and gallic acids, arbutin and catechin being some of the most abundant compounds. Differences in the polyphenol composition among pear varieties were found to be relevant. As a result, such compounds may result in potential descriptors of varietal characteristics.