Classification and adulteration detection of honey from different floral and geographical origins – case of Zambian and Botswana honey

Abstract

The physiochemical properties of three commercial and three real natural honeys from Zambia and Botswana were analysed using methods specified by the International Honey Commission. Some of the parameters were specific conductivity, water and ash contents, pH, and acidity. One commercial honey from Zambia i.e. ZAM 1 had a moisture content of 18.56% and electrical conductivity of 0.725 mS/cm. Furthermore, the honeys were also analysed for adulteration with sucrose, fructose, maltose and glucose. Partial validation of the FTIR method used for adulteration detection gave limits of quantification (LOQ) values that ranged between 1.80 and 5.12% w/v, with calibration curves that were linear indicated by R2 values that ranged between 0.9858-0.9989. The concentration ranges for the sugars were as follows (% in brackets): sucrose (LOQ-6.01), fructose (34.69-43.66), maltose (5.38-12.88) and glucose (25.52-32.57). The volatile classification of the same honeys based on geographic and floral origins was also done forthwith. Classification using gas chromatography – mass spectrometry/solid phase micro extraction (GC-MS/SPME) was accomplished on three commercial and three unprocessed organic honeys (p<0.05). The Automated Mass spectral Deconvolution and Identification System (AMDIS), Metab R, an R platform application and MINITAB version 14 were used for data processing. 17 volatile metabolites in three commercial and 42 in three unprocessed organic honeys were identified, confirmed and formed the basis for differentiation. Database search showed that, the honeys were polyfloral with major ingredients coming from common flowering plants, conifers and other gymnosperms such as Carica papaya L. (Papaya), Monstera deliciosa (Ceriman) and fruits i.e. Guava, melon and pineapple endemic in the areas from which the honeys originated from.