Determination of some heavy metals and selected phenolic compounds in commercial honeys obtained from Northwestern States of Nigeria

Abstract

Natural honey is one of the highly needed products because of its exclusive, high nutritive and medicinal properties, it is among the most adulterated products globally. Honey adulteration is a global concern, it has negative effects on the nutrition and health of consumers and has become a common practice because of the high demand and limited availability of the product. This research aims to evaluate the heavy metals concentrations and the phenolic compounds in honey samples obtained from local sellers and compare the levels with honeys from credible beekeepers in Northwestern states of Nigeria (Kano, Kaduna, Jigawa, Katsina, Sokoto, Zamfara and Kebbi) in order to detect possible adulteration of the products. Results indicated that most of the heavy metals detected Cd (ND-0.10±0.16 μg/g), Pb (0.20±0.11-1.62±1.60 μg/g), Ni (0.03±0.04-0.53±0.46 μg/g), Cu (0.47±0.23-2.61±2.11 μg/g), Zn (5.75±4.04-7.63±131.74 μg/g) and Fe (6.74±1.92-61.43±98.12 μg/g) in honeys from local sellers were above the permissible range set by the International Honey Commission (IHC) and NAFDAC while the levels in samples obtained directly from beekeepers closely complied with the standards. The non-compliance of the metal levels with IHC standards in locally sold honeys could possibly be due to adulteration of the products using metal-contaminated adulterants. However, lower values were recorded for Phenolic compounds: flavonoids (154.5- 521.7 mg/kg) and Phenolic acids (399.6-1075.0 mg/kg) in most of the honeys from local sellers except in honeys from Zamfara state. Generally, results from this study indicate that large percentage of the honey products sold locally in the Northwest Nigeria are suspected to be adulterated mostly with sweeteners while honeys obtained directly from beekeepers were found to agree with IHC standards. It is therefore recommended that pure honeys should be obtained directly from credible beekeepers.