Ultrasonic based determination of apple quality as a nondestructive technology

This research, aimed to apply ultrasonic based technology and develop a portable system for determination of the apple (Golden Delicious) mechanical properties as the quality factor. The main components of the designed portable system are a pair of transmitter and receiver transducers with 40 kHz center frequency, a signal generation unit, a measuring unit of the gain ratio (dB) and phase difference of two signals (input and transmitted), a microcontroller (Atmega 32) and a 16 × 2 LCD display. Mechanical properties of the specimens were distractively measured by an Instron universal testing machine based on the Magness−Taylor method. By combination the physical and ultrasonic attributes and developing the multiple linear regressions, for firmness the model with a good ability of prediction was developed with R and RMSE values of 0.73 and 2.35 N, respectively. For the elastic modulus, the best model had R and RMSE values of 0.64 and 0.18 MPa, respectively. Also for the rupture energy, the model with a high ability of prediction was developed with R and RMSE values of 0.73 and 5.18 mJ, respectively. It was concluded that by using the nondestructive ultrasonic based system to measure the ultrasonic velocity and attenuation of apple, it might be possible to nondestructively assess its mechanical properties.