Mizrach, A., Inst. of Agricultural Engineering, Agricultural Research Organization, Bet Dagan, Israel, Inst. of Agricultural Engineering, P.O. Box 6, Bet Dagan, 50250, Israel
Bechar, A., Inst. of Agricultural Engineering, Agricultural Research Organization, Bet Dagan, Israel
Grinshpon, Y., Inst. of Agricultural Engineering, Agricultural Research Organization, Bet Dagan, Israel
Hofman, A., Inst. of Agricultural Engineering, Agricultural Research Organization, Bet Dagan, Israel
Egozi, H., Inst. of Agricultural Engineering, Agricultural Research Organization, Bet Dagan, Israel
Rosenfeld, L., Inst. of Agricultural Engineering, Agricultural Research Organization, Bet Dagan, Israel

In modern agriculture, with its competitive markets, fruit quality is a significant factor, and mealiness impairs the quality of apples and reduces their market value and price. Retailers are perfectly able to distinguish a mealy product from a fresh one, describing it correctly with terms such as non-juicy, soft, etc. However, there is a need for a reliable method, incorporating appropriate sensors, for the nondestructive testing and classification of apples according to their mealiness; it needs to be designed for use by an untrained person. Several techniques have been suggested in the literature to detect and evaluate mealiness; they include destructive tests such as tensile tests, texture profile analysis, ultrasonic examination, etc., and some nondestructive sensory analysis methods based on, e.g., magnetic resonance, electrical impedance, and NIR. This article suggests a system based on ultrasonic energy absorbance for nondestructive determination of three mealiness levels (fresh, ripe and overripe) in Jonagold and Cox apples. The method is based on the emission of a known level of ultrasonic energy into the fruit flesh and measurement of the attenuated signal received after transmission through the fruit tissue. The strength of the received signal is affected by the mechanical structure of the tissue, the physiochemical quality indices, and any change in the quality attributes of the fruit. The detected sound waves were analyzed in parallel with determination of the mealiness level of the fruit. The results obtained suggest that it is possible to distinguish among the three mealiness levels in Jonagold fruits, but not in the Cox fruits.