Significance of composition and particle size on the shear flow properties of wheat flour

BACKGROUND: Size-based fractionation of flour particles is an important process in wheat milling. Inter-particle cohesion could affect the dynamic separation process and result in loss in throughput. This study quantifies the effect of particle properties that includes physical and chemical characteristics on the shear flow behavior of wheat flour. RESULTS: The cohesion and flow function values of wheat flour at three moisture contents (10%, 12%, and 14%), three particle sizes (75-106, 45-75, and < 45 mu m) and three sifter loads (0.5, 1.0, and 1.0 kPa) were significantly different (P < 0.05). The triggering moisture content and particle size where the flowability shifts from 'easy flowing' to 'very cohesive' were found to be 12% (wet basis) and 45 mu m, respectively. CONCLUSION: The high correlation observed between the chemical composition (damaged starch, protein, and fat) on the physical (bulk and tapped densities) and flow properties (cohesion, flow function, and angle of internal friction) demonstrates that chemical composition significantly contributes towards the differences in dynamic flowability of wheat flours. In addition, fat composition had a significant effect on the differences in flowability of wheat flours due to the increased inter-particulate cohesion. (C) 2016 Society of Chemical Industry