Physicochemical Properties of A- and B-type Granules of Wheat Starch and E. fects on the Quality of Wheat-Based Noodle

This work fractionated native wheat starches into A- and B-type granules fractions to accurately assess granules physicochemical properties and effects on water distribution, storage modulus (E ') and loss modulus (E '') of two type noodles with A- and B-type granules. Pasting viscosity and starch crystallization of A- and B-type granules were determined by Rapid Visco Analyzer (RVA) and X-ray diffraction (XRD) respectively. The noodles were prepared from wheat flour, which 20 % was replaced with the A or B starch fractions, respectively. The water distribution and dynamic mechanical properties of noodles were characterized through Low-field Nuclear Magnetic Resonance (LF-NMR) and Dynamic Mechanical Analysis (DMA). The results demonstrated that A- and B-type granules almost had a round shape with smooth surface. The crystal models of A- and B-type granules were the same but the relative crystallinity were different. A-type granules contained higher starch content, higher ratio between amylose and amylopectin and less damaged starch than B-type granules. B-type granules easily aggregated into clump in deionized water. A- and B-type granules were different in swelling properties and pasting viscosity under the same conditions. A-type granules possessed lower swelling power and water-binding capacity, higher solubility and pasting viscosity than B-type granules. A-noodles (relative to B-noodles) had higher ratio of immobilized water, E ' and E ''.