Influence of genotype on chemical composition and rheological properties of flaxseed gums

Flaxseed gums extracted from different genotypes of flaxseed varied in chemical composition of their constituent polysaccharides. This difference in polysaccharide composition was responsible for their broad diversity in rheological behaviours as measured by small strain oscillatory rheological tests. Twelve flaxseed cultivars from two colour groups (yellow and brown, six of each) were examined in detail. The chemical composition and structure of flaxseed gums were determined by C-13 NMR spectroscopy and monosaccharide analysis. Flaxseed gums appeared to follow a general rule that those containing higher amounts of arabinoxylans (neutral polysaccharides) exhibited shear thinning flow behaviour and 'weak gel'-like properties. Those containing a higher amount of acidic polysaccharides (rhamnose, galacturonic acid) exhibited weaker rheological properties typical of viscoelastic fluid. Gums extracted from yellow seeds exhibited stronger rheological properties than those from the brown group. Of all the cultivars examined, aqueous dispersions of gum extracted from breeding line 84495 exhibited the highest apparent viscosity and storage modulus G'.