Identification of volatile compounds in solvent extracts of honeys produced in South Africa

Abstract

Volatile organic compounds in honey are derived from numerous biosynthetic pathways and contribute in the organoleptic and aromatic properties of honey as well as aid in its floral and geographical origin determination. They are usually extracted from the sugar matrix using various methods associated with varying degree of selectivity and effectiveness. In this study, the volatile composition of three local South African honeys was explored by solvent extraction and identified by a gas chromatograph equipped with a mass spectrometry detector. Thirty-two volatile compounds were identified and classified as hydrocarbons (3), acids (3), aldehydes (3), ketones (3), benzene derivatives (4), terpenes and its derivatives (3), alcohols (6), furans (2) and pyran (1) derivatives and others (4). The compounds found in the relatively highest percentage of area were hexane, methanamine hydrochloride, butanal and acetic acid. Astoundingly, thiophene and N-methyl-D3-Aziridine, essential precursors used for the synthesis of natural products and pharmaceuticals with vital biomedical properties, plus methanamine hydrochloride were the additional compounds identified in these honeys. However, the botanical identification of a honey is based on plant-derived metabolites such as norisoprenoids, terpenes, benzene compounds and their derivatives. Further studies are needed to characterize the aroma constituents as well as to determine the botanical and geographical origins of these honeys in a bid to standardize their quality, to avoid fraud and to authenticate them. Key words: Solvent extraction, volatile compounds, honey, South Africa.