Antioxidant capacity, total phenolics, glucosinolates and colour parameters of rapeseed cultivars.

The antioxidant capacity of twenty nine rapeseed varieties was determined by using ferric reducing antioxidant power (FRAP) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) methods. Mean FRAP (3190-6326μmol Trolox/100g) and DPPH (3194-6346μmol Trolox/100g) values for methanolic extracts of rapeseed cultivars did not differ significantly. Moreover, the total content of phenolics (756-1324mg sinapic acid/100g), glucosinolates (4.2-87.5μmol/g, respectively), erucic acid (0.0-56.1%) and colour parameters of the studied rapeseed cultivars were analysed. Antioxidant capacity determined by FRAP and DPPH methods correlated significantly with total phenolic content (TPC) in rapeseed cultivars (r=0.9332, 0.9339, p<0.001). Also, significant, inverse correlations were found between antioxidant capacity, total phenolics and luminosity (L(∗)) or red colour intensity (a(∗)) of rapeseed cultivars. Principal component analysis (PCA) allowed the rapeseed varieties to be differentiated based on their antioxidant capacities, total amounts of phenolics, glucosinolates, erucic acid and colour parameters.