Chemical composition in varieties of rapeseed and turnip rapeseed, including several samples of hull and dehulled seed

Varieties of spring rapeseed ( n = 10), winter rapeseed ( n = 12), spring turnip rapeseed ( n = 11) and winter turnip rapeseed ( n = 3) were analysed for contents of dietary fibre (DF) constituents, crude fat, crude protein and ash. Most of the varieties were of the double‐low type but four single‐low winter rapeseed varieties and seven yellow‐seeded (triple‐low) varieties were also investigated. Principal component analysis (PCA) made it possible to divide the varieties into different groups. One group, including winter rapeseed varieties and the winter turnip rapeseed variety Kova, generally had high crude fat contents (432‐492 g kg −1 whole seed, DM), low crude protein (181‐221 g kg −1 ) and ash contents (32‐38 g kg −1 ). Another group, consisting of the yellow‐seeded spring turnip rapeseed varieties, had a lower mean content of DF (150 g kg −1 ), due to low content of Klason lignin, than the other categories of varieties (mean contents: 176‐183 g kg 1‐ ). Spring rapeseed varieties generally exhibited lower values of neutral polysaccharide residues than the other varieties studied. It was shown—using PCA—that the individual neutral polysaccharide residues primarily varied in unison. In addition, the presence of fucose‐containing xyloglucan, pectin and galacto‐glucomannan in the seeds was indicated. DF content in manually prepared hulls and dehulled seeds was determined for 10 varieties. The content of dietary fibre polysaccharide residues (DFPR) in the dehulled seeds of spring rape was low (range: 59‐71 g kg −1 ) compared with the other varieties analysed (76–87 g kg −1 ). The content of Klason lignin in yellow hulls was considerably lower (48–63 g kg −1 ) than in dark hulls (224–330 g kg −1 ). Yellow hulls instead had a higher DFPR content (491‐497 g kg −1 ) than dark hulls (341–401 g kg −1 ).