Evaluation of pear firmness by dynamic characteristics of drop impact

Abstract

AbstractThe dynamic resonance frequency based on the dynamic frequency response of pear dropped onto a flat plate was determined by impacted orientation, drop height, material of impact surface, pear firmness and pear mass. Response signals in time domain were detected, and transformed into frequency domain (by means of fast Fourier transform). The dominant frequency (the response magnitude is the greatest) was significantly affected by pear firmness and pear mass. Impact orientation, drop height and impact surface material did not significantly affect the dominant frequency. The dominant frequency increased with increase of pear firmness, and decreased with increasing pear mass. Good relationships were obtained between dominant frequency and Magness–Taylor or pear mass (r2 = 0.716 and 0.771), and the stiffness index (Sc = f2m2/3) regressed on Magness–Taylor firmness had better relationship also r = 0.819). Pear firmness can be predicted by the drop impact method. Copyright © 2007 Society of Chemical Industry