Abstract
An impact force response method was investigated for nondestructive discrimination of internal quality of watermelon, especially maturity and warn damage. Besides, a polynomial equation was fitted to the peak points of auto-correlation function for vibrational signal caused by the impact force for watermelon. As a result, the curve fitting procedure successfully predicted the mass of each ripe watermelon. The unripe and warn damaged watermelon had variations in auto-correlation function and quantified by thresholding the error of predicted mass, while cracked watermelons were detected by thresholding the standard deviation in the curve fitting procedure.
