The IC50 values for the raspberry juice and vitamin C solution were 4.18 and 1.88
mg/mg DPPH, respectively. The raspberry juice with addition of 0.60 μg/mL of GSE
showed the antioxidant activity of 39.2%. The same juice with the threefold concentration
of vitamin C (1.81 μg/ml) exhibited similar activity (33.9%) on DPPH radical.
Antioxidant activity of the same amount of juice without any addition of antioxidants was
15.7%.