CONDENSED TANNINS IN CANOLA HULLS

The total content and the biological activity of tannins in canola hul ls were determined in several samples of hulls of Westar, Cyclone, Exc el, and Delta canola varieties. The contents of condensed tannins in c anola hulls ranged from 14 to 1556 mg of catechin equivalents/100 g of hulls as determined by vanillin assay, up to 8 times more condensed t annins than reported previously. Both cultivar differences and the env ironmental growing conditions may have significant effects on the cont ents of condensed tannins in canola hulls. Statistically significant l inear correlations (P less than or equal to 0.001) were found between the tannin content determined by the vanillin and the 4-(dimethylamino )cinnamaldehyde and the proanthocyanidin assays. Canola tannins had si gnificant biological activity, as determined by the blue BSA assay. Th e results obtained using the proanthocyanidin and biological assays di ffered to a lesser extent than those obtained by the vanillin test. Th is suggests that condensed tannins isolated from low- and high-tannin hulls may differ in molecular weight.