Evaluating the antioxidant activity and the level of 5-hydroxymethylfurfural in honey

Honey is one of the richest sources of antioxidants due to a variety of phenolic acids and flavonoids. Another prime chemical indicator of assessing honey quality is 5-hydroxymethylfurfural (HMF) which indicates the freshness of honey as well as exposure to heat. Increasing HMF above the permissible limit could cause cytotoxic and mutagenic effects. In this study, we evaluate the antioxidant activity and radical scavenging capacity of forty samples of natural and commercial Iranian honey. Also, we determine the HMF content in these samples. This aim was achieved through ferric reducing antioxidant power (FRAP), 1, 1-diphenyl-2-picrylhydrazyl (DPPH) assay, and white methods. Results of DPPH (in the range of 3.13% to 66.61%) revealed there was no significant difference between natural and commercial honey in terms of radical scavenging activity (p˃0.05). On the other hand, the results of FRAP showed that natural honey had a significantly higher total antioxidant capacity than commercial honey (p˂0.05). There was a significant difference between honey samples from different plants, too. Furthermore, there was a significant difference between natural and commercial honey in terms of radical scavenging activity and HMF levels (p˂0.05). The result of HMF content was in the range of 8.64 to 98.48 mg/kg. Eventually, it could be concluded that climate, plant source, process of production and storage have an impact on these parameters. Also, some honey samples have high HMF content due to heat-treated processes or dated products.