Studies on Measuring Quality of Fruits and Vegetables by Acoustic Technique (Part 2)

Influence of Intercellular Space Gas on Longitudinal Wave Velocity and Elastic Moduli of Parenchyma

Abstract

For fruits and vegetables of high water content, internal gas volume fraction, density, longitudinal wave velocity and quasi-static Young's modulus were measured at atmospheric pressure and higher pressure (0.1-1MPa), and the validity of the gas-dispersed model already reported was investigated experimentally. Longitudinal wave velocity was decreased as internal gas volume fraction was increased and this decreasing tendency agreed with the theoretical line. Bulk modulus dominated longitudinal wave velocity, but quasi-static Young's modulus had little influence on wave velocity. Internal gas volume fraction and density were inversely correlated. Physical property predicted by longitudinal wave velocity, therefore, was not only internal gas volume fraction but also density.