DETERMINATION OF PEACH FIRMNESS BY ANALYSIS OF IMPACT FORCE

ABSTRACT IMPACT forces of peaches striking a rigid surface were analyzed as a means for prediction of firmness and, hence, maturity. The impact force characteristics C2 (peak force/(time to peak force)^) and F295 (295 Hz spectrum magnitude) were highly correlated with fruit elastic modulus and penetrometer measurements of flesh firmness, and poorly correlated with mass and radius. These characteristics could be used to distinguish immature and mature peaches from threshold mature fruit, but the firmness sorting resolution was affected by variations in impact location. A band-pass filter circuit was constructed and tested to automatically sense the desired frequency components of the impact force signal.