The correlation data between total polyphenols content and
antioxidant activity also account for the interference from
reducing compounds, such as ascorbic acid, occurring in the
hydrophilic extract tested by Folin–Ciocalteu method. In any event,
in recalculating total polyphenols content by subtraction of a
correction factor for ascorbic acid (data not shown), no correlation
was found between polyphenols content and antioxidant activity.
Thus it was hypothesized that ascorbic acid was the most powerful
compound exerting antioxidant activity in the hydrophilic fraction.
This does not exclude an additive or synergistic action between
hydrophilic and lipophilic bioactive molecules in expressing the
overall antioxidant capacity of kiwifruit.