Abstract
Most powdered substances possess some flow properties such as creep and dilatancy when loaded. In this work, mechanical properties of various powdered food are examined by the use of a modified parallel plate plastmeter.
Logarithmic plots of vertical strain vs. loading time become linear from about 30 sec. after loading. This linearity is independent of the load, and its slope varies with the particle size and absorbed moisture. A linearity is also found in the relation of vertical strain vs. shearing stress on logarithmic scales. By the application of Nutting's equation γ=φ-1σβtκ where γ is the strain, σ the stress, t the loading time and φ a material constant, the “firmness”, φ, β and κ, which signify the property of powdered substances, are obtained from the slopes of linear portions of the above two relations.
Logarithmic φ, β, ane κ were found varying in ranges 6.0_??_8.0, 0.2_??_2.0 and 0.2_??_0.3 respectively. These variations are considered ascribable to differences in particle size, fineness of particle surface structure and absorbed moisture.
