Evaluation of muskmelon ripening based on acoustic response

Four different stages of ripeness have been identified (immature, mature raw, semi-ripe and ripe) in commercial grading of muskmelon. Destructive measurement (by determining firmness, total soluble solids and titratable acidity) of muskmelon ripeness is time-consuming and labour-intensive. Further, conventional visual examination procedures demand expert graders. Hence, there is need for a suitable approach to evaluate the ripeness of muskmelon; a technique that can be scaled-up to on-line applications. The objective of this study was to develop an acoustic resonance based technique to evaluate the ripeness of muskmelon. The developed system consisted of a sample holding unit, impact device, sound acquisition system, signal analyser and computer. Acoustic response parameter, stiffness coefficient was correlated with various destructive parameters. During ripening, stiffness coefficient values decreased from 5.43 x 106 Hz2g2/3 to1.47 x 106 Hz2g2/3. The proposed methodology can be efficiently modified to determine the ripeness of various other horticultural products too.