Antioxidant properties and phenolic content of different floral origin honeys
J. Piljac-Žegarac, T. Stipčević, A. Belščak
Twenty six honey preparations of different floral origin (11 monofloral, 7 heterofloral, 8 special) were tested for total phenol (TP) content and antioxidant/antiradical properties. Commonly employed analytical techniques used to quantify plant antioxidants were used for analysis of various floral origin honeys. The Folin-Ciocalteu test was used to determine the TP content, ferric reducing antioxidant power (FRAP) assay for reducing capacity and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) assays for radical scavenging capacity. The colour intensity measure, ABS450, was used to approximate the contribution of coloured phytochemicals (carotenoids, flavonoids) to the overall antioxidant capacity of honey. Phenolics were most concentrated in Velebit forest honey (116.97 mg ascorbic acid equivalents (AAE)/100 g) and honey with added sour cherry juice (109.81 mg AAE/100 g), which also exhibited the highest FRAP value (459.21 μm Fe(II)) as well as DPPH· and ABTS·+ radical scavenging capacities (43.04 and 65.24 mg AAE/100 g, respectively). Overall, heterofloral honeys exhibited the highest mean TP content (58.75 mg GAE/100 g), the highest mean reducing capacity (57.66 μM Fe(II)) and the best mean radical scavenging properties with respect to both DPPH· (16.66 mg AAE/100 g) and ABTS·+ radicals (35.27 mg AAE/100 g).