QUALITY CHARACTERISTICS OF YELLOW-SEEDED BRASSICA SEED MEALS - PROTEIN, CARBOHYDRATES, AND DIETARY FIBER COMPONENTS

A comprehensive evaluation of the nutritive profiles of the meals derived from 26 Brassica seed meals of yellow-seeded B. napus, B. rapa, B. juncea, and B. carinata genotypes and 7 samples of conventional brown-seeded canola was undertaken. The evaluation involved the analyses of sucrose, galactooligosaccharides, protein, total dietary fiber, ash, and residual fat. The fiber components determined included nonstarch polysaccharides, lignin and polyphenols, cell wall protein, and minerals. On average, in comparison to brown-seeded, yellow-seeded types contained more sucrose (8.7% vs 7.5%) and protein (44.5% vs 42.7%) but similar amounts of oligosaccharides (2.3% vs 2.5%), ash (6.9% vs 7.0%), and nonstarch polysaccharides (20.4% vs 19.7%). Dietary fiber averaged 28% for yellow-seeded samples (minimum 22%, maximum 32%) and 33% for brown-seeded samples (minimum 28%, maximum 36%) and was negatively correlated (r -0.71) with protein content. Lower dietary fiber content in yellow-seeded samples as compared to brown-seeded samples was reflected in a lower content of lignin with associated polyphenols (4.3% vs 8.2%) and less wall-inserted protein (2.3% vs 3.3%) and minerals (0.7% vs 2.4%) associated with the fiber fraction. It may be surmised that future cultivars of yellow-seeded Brassica oilseed crops will have improved nutritive value.