Antioxidant activity and phenolic composition of herbhoneys

A study of 10 herbhoneys of various origin revealed differences in their antioxidant activity and profiles of phenolic acids and flavonoids. The total phenolic content of herbhoneys determined spectrophotometrically varied between 21.7 and 75.3 mg gallic acid equivalents per 100 g product, and the total flavonoid content ranged from 6.9 to 28.5 mg quercetin equivalents per 100 g. Dark herbhoneys, such as raspberry, thyme, hawthorn and black chokeberry, exhibited a high antioxidant activity and contained high total levels of polyphenols and flavonoids. There was a significant linear correlation between total phenolic and flavonoid contents and antioxidant activity in the reactions with DPPH and ABTS+ free radicals. The profiles of phenolic acids and flavonoids determined by HPLC depended on the variety of herbhoney. Among the products studied, raspberry and thyme herbhoneys were the richest in phenolic acids and flavonoids. The dominant phenolic acid in most samples was p-coumaric acid; the herbhoneys contained also a considerable amount of gentisic acid. The dominant flavonoids were hesperetin and naringenin. Thyme herbhoney had an especially high quercetin content.