Significance of storage conditions on the flow properties of wheat flours

Flow properties of wheat flours are influenced by their intrinsic properties and environmental conditions during handling. This study evaluated the effects of environmental conditions (temperature and relative humidity- %RH) and flour properties (particle size and wheat class) on the flow properties of wheat flours. Size fractions from hard red winter (HRW) and soft red winter (SRW) wheat were produced through sieving. Flour fractions were then exposed to various temperature (25 and 35 degree Celsius) and relative humidity (50, 60, and 70%RH) combinations (t=3 h) to evaluate the effects of environmental conditions. Flow indicators (Hausner ratio – HR and compressibility index - CI) and flow (bulk, dynamic, and shear) properties were measured for the wheat flours after treatment. Shape analysis showed that all flour fractions were spherical based on their aspect ratio (>0.7) and elongation (<0.3) values. Flow properties indicate that soft wheat flours had poorer flowability compared to hard wheat flours. Lower flow function (FFc) were observed for finer flour fractions (FFc<4.0) of both flour types relative to the coarser particles (FFc>4.0) which indicates poorer flowability. Higher humidity levels (60 and 70%) also caused poorer flowability for the wheat flours after exposure. The results from this study show that both environmental factors and flour characteristics have significant effects on flour flow properties. Handling wheat flours at lower humidity levels and higher temperatures improve flowability. Hard wheat flours were more flowable than soft wheat flours; coarser fractions from both wheat types flow better than finer fractions.