PHYSICOCHEMICAL PROPERTIES OF COMMON AND TARTARY BUCKWHEAT STARCH

Physicochemical properties of starch of three common (Fagopyrum escule ntum) and three tartary (F. tataricum) buckwheat varieties from Shanxi Province, China, were compared. Starch color, especially b, differed greatly between tartary (7.99-9.57) and common (1.97-2.42) buckwheat, indicating that removal of yellow pigments from tartary buckwheat flo ur may be problematic during starch isolation. Starch swelling volume in water of reference wheat starch (2.8% solids and 92.5 degrees C) wa s 20.1 mt; for the three common buckwheat starches it was 27.4-28.0 mt ; and for the three tartary buckwheat starches it was 26.5-30.8 mt. Pe ak gelatinization temperature (T-p) in water was 63.7 degrees C for wh eat starch, 66.3-68.8 degrees C for common buckwheat and 68.8-70.8 deg rees C for tartary buckwheat. T-p Of all samples was similarly delayed (by 4.0-4.8 degrees C) by 1% NaCl. Enthalpy of gelatinization (Delta H) was higher for all six buckwheat starches than it was for wheat sta rch. However, one common buckwheat sample had significantly lower Delt a H than the others. Starch pasting profiles, measured by a Rapid Visc o-Analyzer, were characteristic and similar for all six buckwheat star ches, and very different from the reference wheat starch. A comparison of pasting characteristics of common and tartary buckwheat starches t o wheat starch indicated similar peak viscosity, higher hot paste visc osity, higher cool paste viscosity, smaller effect of NaCl on peak vis cosity, and higher resistance to shear thinning. Texture profile analy sis of starch gels showed significantly greater hardness for all buckw heat samples when compared to wheat starch.