Effect of water-soluble and insoluble non-starch polysaccharides isolated from wheat flour on the rheological properties of wheat starch gel

Water-soluble (WSP) and insoluble non-starch polysaccharides (WIP) were isolated from wheat flour to evaluate the effects of WSP and WIP on starch gel properties. Isolated WSP and WIP were added to two types of isolated wheat starch with different amylose content at a concentration of 3% based on the dry weight of starch. 30% starch gels were prepared and stored at 5 °C for 1, 8, or 24 h. The dynamic viscoelasticity of 30% starch gels mixed with WSP and WIP was measured using parallel plate geometry, showing that WSP and WIP affected the elastic component of starch gels in opposite ways. Adding WIP increased the storage shear modulus (G′) of starch gels, while adding WSP decreased G′ and dramatically increased the loss tangent (tan δ=G″/G′).