A Measuring Method of Mechanical Properties as an Assembly of Cooked Rice Grains

Abstract

Man will break the assembly of cooked rice for the first thing on eating, but no report for determination of mechanical properties on this state. Brabender Viscograph was used for a simple and easy apparatus of determining shear mode deformation to cooked rice. Cooked rice was packed into the bowl of paddle type and set to the pin mixer of 7 pin type attached to Viscograph VS 6. These were cut off circuits of the bowl rotation and heating power, then the recorder was started and the bowl was twisted for 1 radian (1, 000 BU) by hand, and fixed. The recorder chart will show an exponential relaxation curve, the curve was converted into a semi-log form graph and calculated to viscoelastic parameters by the method of successive residuals. G₁λ A was obtained 30-55 Pa and η₁ showed 0.7-5 × 10⁵ Pa. s of non-glutinous rice, and steamed waxy rice showed G₁, 30-60 Pa, η₁, 2.6-14 × 10⁵ Pa. s. Thailand rice was G₁, 20-35 Pa, η₁, 5-14×10⁵ Pa. s, which showed lower values after the break the assembly of cooked rice than the before, however, domestic rice showed nearly reverse the trend. G₂ of domestic rice were showed about ten Pa, and η₂ was two thousand Pa. s, but Thailand rice showed no part of exponential curve almost never.