Non-Destructive Estimation of Mechanical and Chemical Properties of Persimmons by Ultrasonic Spectroscopy

Fruit properties, including ripeness, are still being measured destructively in most countries. Recently, an increased attention has been given to non-destructive methods, such as ultrasonic techniques, for quality assessment of food commodities. The aim of this study was to evaluate the feasibility of ultrasonic spectroscopy to monitor the changes of mechanical properties (rupture force and modulus of elasticity) and chemical properties (soluble solids content) in two cultivars of persimmons (Karaj and Shomali) during 3 weeks of storage. Samples' ultrasonic properties such as ultrasonic velocity and attenuation coefficient were analyzed with transducers, and their textural properties were obtained using destructive compression test and their refractometric properties were measured from its fresh-squeezed juice in laboratory. Mechanical and chemical properties were statistically modeled from ultrasonic parameters. The results showed that our proposed model could predict persimmons' mechanical and chemical properties well, i.e., rupture force (R-2 = 0.893/0.837; RMSE = 3.683/3.849 for Shomali and Karaj cultivars, respectively), modulus of elasticity (R-2 = 0.826/0.861; RMSE = 0.231/0.217 for Shomali and Karaj cultivars, respectively) and soluble solids content (R-2 = 0.931/0.987; RMSE = 0.519/0.851 for Shomali and Karaj cultivars, respectively).