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Evaluation of 5-Hydroxymethylfurfural (HMF) Concentration and Physicochemical Properties in Fresh and Aged Tualang Honey

The quality and purity of honey are generally indicated by the physicochemical properties including 5-hydroxymethylfurfural (HMF) level, a neo-formed contaminant with genotoxic potential. The concentration of HMF in honey usually increases as storage duration prolonged. This study investigated the differences in the physicochemical properties and the HMF concentration of fresh (stored within six months) and aged (stored for four years) tualang honey (TH), as well as the correlation between these two main parameters. Each of the physicochemical properties of TH was evaluated using standard established protocols. Meanwhile, the determination of HMF concentrations was conducted using High Performance Lipid Chromatography (HPLC) method. Results obtained indicated that the HMF contents in fresh TH (27 mg/kg) was found to be lower whereas aged TH sample contained greatly higher concentration (1426 mg/kg) when compared to the international recommended value of HMF for tropical honeys (< 80 mg/kg). The physicochemical properties (pH, free acids, lactones, total acidity and moisture content) of TH showed significant correlation with HMF concentration. These parameters could be used as rapid assessments for TH quality from different storage periods. The current findings suggest that there were significant modifications in the chemical reactions between TH of different storage durations. TH stored for four years might be not suitable and safe for human consumption. 
Keywords: physicochemical properties, 5-hydroxymethylfurfural, aged honey, storage duration