Physicochemical Characterization of Honey from Selected Counties in Kenya

Abstract

Honey is a natural product with unique flavour and is highly nutritious. It is produced by honeybees and consumed by many. It contains sugars, proteins, water and minerals just to mention a few. There is growing interest in the food industry to characterize food samples for mineral content, in particular. The main objective of this study was to characterize local honey based on physicochemical analysis and mineral content. The parameters that were used in characterization of honey, in this study include determining physicochemical parameters like pH, sugars, Hydroxymethylfurfural (HMF) and trace elements. This was achieved by the measurements of pH, free acidity using titration, HMF and sugars using HPLC and trace metals using EDXRF and ICP-OES. A total of sixty (60) samples of refined honey from two regions; Baringo and Kitui were studied. Sixteen (16) elements, namely Fe, Cu, Mn, Zn, Cr, Ba, Mo, Ni, Ti, As, Cd, Co, Hg and Sn were assessed. The most abundant elements were Fe and Zn with mean concentrations of 19.82 ± 2.74 μg/g and 2.89 ± 0.77 μg/g, respectively for Baringo samples and 24.49 ± 3.38μg/g and 1.92 ± 0.41 μg/g for Fe and Zn, respectively for Kitui samples. Cu levels averaged 1.99 ± 0.38μg/g for Baringo samples and 1.04 ± 0.16 μg/g for Kitui samples. Cr and Ba levels were less than 0.25 μg/g in all samples from both regions. The other elements; Mo, Ni, Ti, As, Cd, Co, Hg and Sn were below their detection limits. The pH average values averaged 3.64 ± 0.28 and 3.46 ± 0.31 μg/g for honey samples from Baringo and Kitui, respectively. These levels are within the EU recommended limits and are consistent with most studies. Naturally, honey is acidic and thereby allows for self-preservation. In general, free acidity averaged 29.67 ± 5.38 milliequivalents/Kg for Baringo and 30.85 ± 4.27 milliequivalents/Kg for Kitui, all values below the KEBS recommended limits of a maximum of 50 milliequivalents/Kg. The total sugars were found to be 65.29% and 59.9% for Baringo and Kitui, respectively. The average HMF levels were 30.05 ± 3.55 mg/Kg and 3.91 ± 0.18 mg/Kg for Kitui and Baringo, respectively. A few samples from Kitui had elevated levels of sucrose (> 5%) and HMF (> 100 mg/Kg), an indication of adulteration or prolonged storage periods. After subjecting the results to statistical analysis (student’s t-test), all parameters of the samples from Baringo and Kitui had significant difference, except for free acidity, Fe, Mn and Cr levels. Maltose were not present in Kitui samples, and uniquely distinguishes between the honeys from the two regions. In general, these results indicate good quality honey free of toxic heavy metals.