The impact of α-amylase of normal mature wheat grain on starch pasting properties of wheat flour

Starch pasting, one of important starch properties, has a strong correlation with nutritional and processing properties of cereal grains. α -Amylase activity is one of the most important factors that affect the pasting properties of starch. However, there are few studies on the effect of α -amylase activity on the pasting properties of normal mature wheat grains in China. In this study, a total of 30 wheat cultivars were used for the determination of the falling number (FN), total α -amylase activity, pasting properties of wheat flour with and without AgNO 3 , and SDS-PAGE separation of α -amylase protein. The analyzed wheat accessions showed wide variation in the total α -amylase activity (OD value) and FN, with a range of 0.12–2.87 and 62–524 s, respectively. According to the FN and total α -amylase activity, these accessions could be subdivided into three categories: FN was 122.40 (± 20.25) s, 373.67 (± 13.81) s, and 452.00 ( ± 3.39) s for categories I, II, and III, and the total α -amylase activity (OD value) was 2.35 (± 0.21), 0.74 (± 0.06), and 0.22 (± 0.00) for I, II, and III, respectively, each of them showed significant variations in the total α -amylase activity and had obvious differences in the intensity of SDS-PAGE α -amylase bands. The differences in starch pasting properties among the wheat accessions were mainly controlled by genotypes. Late maturity α -amylase significantly decreased pasting parameters of wheat flour, including peak viscosity, trough viscosity, and final viscosity, and enlarged the pasting differences among the wheat accessions. The total α -amylase activity in wheat significantly negatively correlated with FN ( r = -0.97, P < 0.01) and with Δ PV (difference between peak viscosities with and without AgNO 3 ) ( r = 0.84, P < 0.01). both FN and Δ PV predicted the difference in the total α -amylase activity among the wheat accessions. The wheat accessions under study showed significant variation in the total α -amylase activity, which significantly decreased the starch pasting parameters. The activity of α -amylase should be evaluated in a wheat breeding program or wheat food processing.