Insoluble condensed tannins of canola/rapeseed

The contents of soluble, SDS-extractable, and insoluble condensed tannins were determined in canola/ rapeseed hulls from several varieties by utilizing the proanthocyanidin assay. The total amount of tannins in rapeseed/canola hulls ranged from 1913 to 6213 mg per 100 g of oil-free hulls. Insoluble tannins predominated in canola/rapeseed hulls and comprised from 70 to 95.8% of total tannins present. The amounts of SDS-extractable tannins were comparable to those of soluble tannins but constituted only 4.7-14.1% of insoluble tannins present.