Non-destructive Apple Firmness Measurement Using Acoustic Impulse Response

The acoustic impulse response method used in this research to determine the firmness of the apple fruit. Some apples of the Gala variety stimulated by a lightweight and small pendulum, with a gentle tap. Therefore, an impulsive sound generated. The sound of the impulse transmitted by the microphone to the computer. Accordingly, the sound transformed by the Fourier transform from the time domain into the frequency domain consequently the resonance frequencies of the apple fruit determined. Resonance frequencies used to calculate the firmness index of fruits. The device which controlled by the computer designed to do this. This device automatically hits the apple. At the time of the collision, the sound emitted from the tap transmitted by the microphone to the computer. The created sound stored by the software. Then the Fourier transform done on it. Therefore, the resonant frequencies obtained in the frequency domain. This device equipped with a load cell that measures the weight of the fruit and transmits it to the computer. The apple firmness index depends on its weight in addition to the resonant frequency. The results show that the firmness index obtained from the acoustic method have 84.62% correlation with the results of the puncture test as the reference.

Keywords:

Nondestructive , Acoustic , Apple , Food quality.