Proanthocyanidin contents
Proanthocyanidin determination was carried out by the
vanillin method4. 1 mL of the aqueous extract was mixed
with 2 mL of a freshly prepared vanillin solution (1 g/
100 mL of 70% H2SO4) and maintained 15 min at 20 °C.
The absorption was measured at 500 nm. Calibration was
performed with catechin aqueous solutions (2 μg - 40
μg mL-1) and a molar absorbance of 34.3 x 103 was attained
in our conditions.