Botanical origin of monovarietal dark honeys (from heather, holm oak, pyrenean oak and sweet chestnut) based on their chromatic characters and amino acid profiles

An early optimisation of the o-phthaldialdehyde (OPA) method for the HPLC-fluorimetric analysis of amino acids in honey and bee-pollen made feasible the quantifi- cation of 23, which included five infrequently searched for. Forty samples of monovarietal dark honeys, from four botanical origins, were analysed for their amino acids’ profile (which included proline) and their colour. In order to test for their botanical classification stepwise linear discriminant analysis was applied to a number of variables made from a selection of analytical results and simple mathematical functions of them. This allowed, firstly, distinguishing honeys from these four botanical sources with 85.0% cross-validated grouped cases correctly classified. A second application was made for the group of honeydew honeys—a matter of particular interest since no chemical or microscopic method exists for the honeys from holm oak and oak. Ninety-five percent of the cross-validated samples were correctly classified, only one sample was misclassified.