CLASSIFICATION OF AVOCADO BY FIRMNESS AND MATURITY

Table‐ripe soft avocado cannot be shipped or stored for more than a few days. Thus, it is common practice to store and ship firm, tree‐ripe avocado, while the consumer may soften the fruit as required. A human sorter cannot distinguish between a freshly picked firm avocado and a somewhat softer semiripe fruit, yet the accelerated evolution of ethylene by even several ripe fruits, may prematurely ripen a whole shipment. A sensor system, for nondestructive sensing of avocado firmness is presented, based on vibrationally exciting one side of the fruit, while measuring the transmitted vibration energy on its other side. Special signal processing hardware and software was developed for computing several alternative firmness indexes, highly correlated to the standard piercing force, destructive, test method. Optimal classification algorithms were developed, whereby the fruit may be classified into two or three firmness grades. In both cases, the actual contamination of the firm fruit class by soft fruits was only 3.3%, while the overall classification accuracy was about 90%. Copyright © 1990, Wiley Blackwell. All rights reserved