Free amino acids, oxalate and sulphate for honey characterization

Brunella Carratù, Marco Ciarrocchi, Maurizio Mosca and Elisabetta Sanzini

The purpose of this study was to assess the usefulness of free amino acid profile and sulphate and oxalate content in order to characterize the floral origin of honey. Fifteen Italian honey samples from ten different floral types and three honeydew samples were analysed. Amino acids were determined by an automatic precolumn derivatization with fluorenylmethyl-chloroformate (FMOC-Cl) and by reversed-phase liquid chromatography with fluorescence detector.The anions were separated by an anionic column using a conductimetric detection. The  results obtained show that glutamic acid, proline and tyrosine were major components  in floral honeys. However, the overall amino acid profile did  not enable the botanical origin of honey samples to be distinguished as a rather high variation among honeys from the same botanical source and between honey types from different floral origin was found. It was observed that all the samples contained sulphate and oxalate, and that differences of medium values between the honeydew and floral honeys group were significant. Anion analysis could allow the distinction of honeydew from floral honeys  in combination with results of other physicochemical parameters. However, the number of samples must be increased in order to obtain more significant results.

 honey, floral origin, free amino acids, oxalate, sulphate