Rapid Separation on Activated Charcoal of High Oligosaccharides in Honey

Abstract

A method using different proportions of water/ethanol solutions and activated charcoal was optimised to fractionate honey carbohydrates. Samples (0.5g) were treated with 3g of activated charcoal and monosaccharides were removed using 90/10 water/ethanol solution (v/v). Oligosaccharides with a degree of polymerization (DP) from 3 to 14 were recovered using 50/50 water/ethanol solution (v/v) and analysed by High Performance Anion-Exchange Chromatography coupled with Pulse Amperometric Detection (HPAEC-PAD). Molecular weight distribution of these fractions was determined by size exclusion chromatography (SEC) and matrix-assisted laser desorption/Ionisation time-of-flight (MALDI-TOF) mass spectrometry. Oligosaccharides were analysed in ten honey samples. Although tri- and tetrasaccharides were the main constituents, noticeable variations in higher oligosaccharide contents were observed. The sample preparation treatment proposed here is simpler and less time-consuming than the charcoal/celite columns used in the official method. Moreover, the results obtained here contribute to knowledge of the oligosaccharide fraction of honey, which could be relevant for determining honey nutritional properties and to control honey authenticity.