Sensing and analysing the acoustic response of avocado and mango using a flexible piezoelectric transducer.
Shmulevich I., Galili N., Benichou N.
Author Affiliation: Dept. of Agricultural Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel.
Acta Horticulturae : 121-126
Abstract : A method to determine the firmness of mango and avocado fruits by monitoring their acoustic response is described. The method is based on a soft piezoelectric film transducer that senses the vibrations of a fruit that is struck gently by a small pendulum. The firmness index of the fruit, which is a measure of its elastic properties, is determined by fruit mass and first resonant frequency. Two avocado cultivars and one mango cultivar were tested nondestructively during their shelf-life by the acoustic method for firmness evaluation. The measuring technique was simple, fast and repeatable. The firmness index correlated well with softening of the fruits over time. It was concluded that the fruits could be classified nondestructively according to firmness and expected shelf-life, for efficient marketing. Reasonably high correlation was found between the firmness index and results of destructive tests in mango, including penetration, compression and Brix tests. Lower correlation was found between the penetration force and firmness index in avocado. According to these results, it might be possible to evaluate the ripening parameter of the fruit nondestructively by the acoustic firmness test.