Production of a remote measuring system of fruit softening using laser beams and an acoustic wave

点击翻译按钮获取中文摘要

The following results were obtained ;(1) When kiwi fruit was vibrated, the Doppler shift of laser beam reflecting from the surface of the fruit was precisely determined by a laser Doppler vibrometer.(2) Amplitude of the vibration of fruit was monitored from 5 to 2000Hz, and several resonance peaks were detected. The resonance frequency decreased when an apple fruit was soften, as reported, but the decrease was not observed in other fruits, suggesting that the resonance frequency is not the best index for the fruit softening.(3) The shift of acoustic waves was observed, when the fruit proceeds softening. There was a good correlation between the phase shift and fruit softening in peach, pear, and citrus orange.(4) The phase shift reflects the inside organization of citrus fruit.(5) The differential signal between an accelerometer attached to the stage of vibrometer and the laser Doppler measuring machine tells the precise vibration signal derived from the test fruit.From these results, the fruit softening measurement system using a laser beam is superior to any other reported method, and is an excellent remote and non-destructive method to evaluate qualitatively and quantitatively the degree of fruit softening. Although we could not produce a prototype of fruit sorting machine, the algorism for evaluating the fruit texture is still being processed in Matsushita-Kotobuki Electronics Industries Ltd.