The physicochemical and pasting properties of purple corn flour ground by a novel low temperature impact mill

Purple corn flour (PCF) was prepared by a low temperature impact mill (LTIM) with various air classifier speeds (300, 600, 1200 and 1800 rpm). The effects of processing speed on physicochemical and pasting properties of PCF were investigated. Particle size (D[4,3]) of PCF decreased from 442 μm to 35 μm. The color of PCF became redder supported by increased a* values (from 2.12 to 6.90). As compared with untreated sample, the bioactive component content and antioxidant properties of LTIM-treated PCF increased at low speed (300–600 rpm), then kept constant with further increasing speed. Furthermore, LTIM distinctly changed the pasting properties of PCF, which was demonstrated by lower viscosities, pasting temperature, retrogradation tendency. This change was related to decreased particle size, increased damage starch content, improved hydration properties and promoted destruction of crystal and microstructure. The information obtained may enhance the high-value utilization of functionally superfine ingredient in food applications. Poor palatability and processing characteristics of whole cereal flour limited its utilities in food industries. Superfine grinding is regarded as one of the effective ways to reduce these problems. However, some superfine grinding technology have some problems such as temperature rise and large dust. A low temperature impact mill (LTIM) recently designed overcame the drawbacks. The present research provided information that LTIM was a good method to pulverize cereals and could be used for the manufacture of functionally superfine ingredient.