A Transient Method for Determining Dynamic Viscoelastic Properties of Solid Foods

Abstract

This article describes a transient dynamic method for measuring the complex modulus of solid foods over a range of frequencies from one single loading test. Mathematical justifications for the proposed method are given and the instrumentation system for performing the transient dynamic tests is described in the article. Experiments were conducted to measure the complex modulus of apples and potatoes and its relationship with initial stress and vibration input. The magnitudes of the complex modulus increased by 50% for the apples and 80% for the potatoes as the frequency increased from 0 to 800 Hz. The phase angle generally decreased with frequency. As expected, initial stress had a significant effect on the magnitude of the complex modulus, but not on the phase angle. Vibration amplitude had little effect on the magnitude and phase angle. The values of the complex modulus for apples and potatoes measured from the transient dynamic tests were not significantly different at the 0.05 level from the steady-state sinusoidal tests at frequencies of 200, 400, and 600 Hz.