MODELS OF ULTRASONIC PARAMETERS TO ASSESS AVOCADO PROPERTIES AND SHELF-LIFE

An ultrasonic testing technique was applied for non-destructive qualit y evaluation of avocado fruit and quantitative relations were establis hed between ultrasonic parameters and maturity related factors. The fr uits of the same batch and picking date softened at different storage times, a phenomenon which was attributed to different biological ages of the fruit at the picking date. Time-shifting of the test results of each fruit according to its firmness reduced the scatter of the exper imental data. Second-order polynomial expressions represented well the changes in attenuation of the ultrasonic signals and the firmness of the fruit with storage time. A cubic equation represents fairly well t he wave velocity of the ultrasonic signals versus time. A linear relat ionship was found between attenuation of the ultrasonic signal and fir mness as measured in a cone penetrometer test. It was concluded that e quations of this type may be used for prediction of ripening and shelf -life of avocado fruit, and could replace the commonly used penetromet er method. Further steps, such as the averaging of repeated measuremen ts, may be needed to reduce scatter when predicting the maturity of in dividual fruits. (C) 1996 Silsoe Research Institute