SENSING AND ANALYZING THE ACOUSTIC RESPONSE OF AVOCADO AND MANGO USING A FLEXIBLE PIEZOELECTRIC TRANSDUCER

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 varieties and one mango variety were tested nondestructively during shelf-life by the acoustic method for firmness evaluation.
The measuring technique was found to be simple, fast and repeatable.
The firmness index followed well the 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.

II International Symposium On Sensors in Horticulture

I. Shmulevich, N. Galili, N. Benichou

acoustic, frequency, firmness, piezoelectric film, fruit, mango, avocado

https://doi.org/10.17660/ActaHortic.1998.421.11