Structure and physicochemical properties of two waxy wheat starches

The objective of this study was to determine the primary influences of amylopectin (AP) on starch properties using two waxy wheat starches with different pasting properties. Compared with Yang Nuo Mai 1 (YNM1) starch, Ning Nuo Mai 1 (NNM1) starch had a greater average granule diameter, hot water solubility, gelatinization enthalpy, higher pasting viscosity, but lower retrogradation enthalpy. NNM1 starch had a greater proportion of AP long chains, and lower proportion of AP short chains. Therefore, NNM1 starch had a greater degree of crystallinity as well as stronger resonance intensities at the C1, C2, C3, C5, and C6 by solid-state ¹³C CP/MAS NMR. These results suggested that the proportion of long AP chains (DP ≥ 37) is the main influencing factor in determining waxy starch physicochemical properties. In addition, the proportion of short AP chains (DP 13-24) plays a role in promoting retrogradation of waxy wheat starch.