IMPULSIVE EXCITATION OF ACOUSTIC VIBRATIONS IN APPLES FOR FIRMNESS DETERMINATION

ABSTRACT Apple modulus of elasticity was readily predicted (r^ > 0.76) from acoustic resonant frequency vibrations caused by an impulse striking the apple. Magness-Taylor fiminess was poorly predicted (r^ < 0.27) using the same technique. An elastic sphere model was developed that utilized an observed resonant frequency to predict the modulus of elasticity of the apple. These predictions were compared with measured values of Magness-Taylor firmness and modulus of elasticity..