The alcohol insoluble residue (AIR) preparation was based on
the method by with some modifications. 100 g of milled peels were washed three times with ethanol, to remove any alcohol soluble phenolics (the first time with
600 mL of boiling 70% v/v ethanol solution for 5 min, the second
time with 600 mL of boiling absolute ethanol for 5 min, the third
time with 600 mL of absolute ethanol at room temperature for
5 min), then washed in 200 mL acetone. Between washings, the
material was filtered through a 10 lm nylon mesh. The AIR was
air dried at room temperature.