Direct shear testing of flowability of food powders
M. Stasiak, M. Molendahttps://doi.org/10.17221/4919-RAECitation:Stasiak M., Molenda M. (2004): Direct shear testing of flowability of food powders. Res. Agr. Eng., 50: 6-10.
The flow properties were determined for two groups of food powders used in industry: cereal powders and non-starch powders. Materials were different in mean sizes of particles d* ranging from 0.033 mm for potato flour to 4.449 mm for oatmeal. Experiments were performed in 60 mm in diameter direct shear tester (Jenike shear tester) for four values of consolidating stress r: 30, 60, 80 and 100 kPa. The highest values of flow function (FF) and the widest range of its variability (ranging from 0.5 kPa to 35 kPa) were found in the case of pearl barley groats. For the non-starch powders values of FF were more stable and did not exceed a limit characteristic for easy flowing materials. The highest values of FF in the group of the non-starch materials were obtained for icing sugar (from 19 kPa to 24 kPa) while the lowest found were values of FF for salt (from 3 kPa to 7 kPa). Powdered milk and potato flour showed the widest variability of FF values within the non-starch materials.Keywords:
powders; flow function; consolidation pressure; flow properties; milk powder; cereal powder