Watermelon Maturity Determination in the Field Using Acoustic Impulse Impedance Techniques

A portable system using acoustic impulse impedance techniques was developed to nondestructively determine watermelon maturity. The system was used in the field to measure the maturity of three watermelon varieties ‘Allsweet’, ‘Sangria’ and ‘King of Hearts’. Frequency domain parameters from the impulse response were compared with sugar content, flesh color, Effe-gi firmness and mass for individual melons. The effect of testing the melons in their natural growing position and resting on a hard base was determined. The system was also examined as a method to detect hollow heart in watermelons. Correlations between acoustic and destructive maturity parameters indicated relationships were too weak to be of value for maturity sorting. Relationships between acoustic parameters and level of hollow heart were weak for ‘King of Hearts’ but much stronger for the ‘Black Diamond’ cultivar.