Study of the ball milling condition effect on physicochemical and structural characteristics of wheat flour

An investigation of the changes in the properties of starch due to mechanical and thermal effects was taken. The milling temperature and time were strictly controlled, and the particle size, relative crystallinity, damaged starch content, pasting characteristics, and thermal properties of the ground sample from different feed sizes were determined. The results showed that the feed particle size had a significant influence on the particle size distribution, peak viscosity, and final viscosity of the milled product at the initial milling stage. Minimum feed particle size (3.75 ~ 623 μm) flour has the largest peak viscosity (2,881.5 ± 58.7 cP & 2,895.0 ± 38.2 cP) after milling 15 min. The sieving results showed that better breakage effect for coarser particle size after same milling time, particularly under normal temperature. The data of relative crystallinity indicating that keeping a lower temperature range (<25℃) during the milling process may be beneficial to the protection of the starch crystallization. In addition, the difference of thermal properties of the milled products may be caused by the different degrees of starch exposure in endosperm granules and the change of surface protein properties during milling. Novelty impact statement The feed particle size has a significant effect on the peak and final viscosities of the short-time ball milling flour. Cryo-milling can protect the relative crystallinity of wheat granules. The degree of starch granule exposure affects the impact of mechanical force during milling.