Antioxidant activity of different grades of maple syrup as determined by the hydrophilic oxygen radical absorbance capacity method

Abstract

Maple syrups are prepared by thermally concentrating maple sap. Based on their clarity, density and characteristic taste, they are divided into 5 grades: extralight, light, medium, amber and dark. This study aimed to evaluate differences in antioxidant activities among grades by the hydrophilic oxygen radical absorbance capacity (H-ORAC) method. The results demonstrated that H-ORAC values varied widely depending on the degree of brown coloration; darker-colored maple syrups showed stronger antioxidant activity. The darker-colored grades of maple syrup also contained more reducing sugars (fructose and glucose) than the lighter-colored ones; however, the grade had little impact on the content of free amino nitrogen in the syrup samples. The present study suggests that the brown pigments (melanoidins) produced by condensation of amines and reducing groups may contribute significantly to the antioxidant activity of maple syrups.