ULTRASONIC DEVICE FOR AVOCADO SHELFLIFE PREDICTING AND MATURITY DETECTION.

An ultrasonic testing technique was applied to a post-harvested avocado fruit to predict its shelf life and to assess its quality. Measurements of ultrasonic wave amplitude and transit time over the peel of the fruit were used for calculation of wave attenuation and velocity in each individual fruit. Nondestructive ultrasonic tests were performed daily on avocado fruits, until full ripening was detected. Penetration measurements of firmness and physiological tests of dry weight and oil content of the fruit tissue were conducted using accepted methods. Results of the ultrasonic tests were compared with destructive penetration tests, and with physiological tests. Average values of the ultrasonic wave attenuation could be correlated well with storage time and with the ripening process of the avocado. A linear model well represented the changes in attenuation of the ultrasonic signals in the fruit and second-order polynomial expressions the changes in the firmness of the fruit, during storage at room temperature. The wave attenuation increased during storage while the firmness of the fruits decreased. The dry weight of avocado and its oil content were correlated with its ultrasonic parameters and mechanical properties. It is suggested that changes in the ultrasonic parameters during storage may be used to evaluate oil content and firmness to predict shelf life of avocado fruit.