Development of measuring system of maturity and quality of fruits by laser Doppler method

点击翻译按钮获取中文摘要

Confirmation of vibration mode has revealed that the elasticity and viscosity of fruits was calculated from the vibration peak at second resonance. Software was made for the calculation and it enables us to evaluate automatically the softening of fruits by elasticity and viscosity. It also prompted us to proceed the program for high-speed selection of fruits at every 0.1 second. Analysis of cell wall polysaccharides suggests that degradation of pectic polysaccharides results in the viscosity decrease and that of xyloglucan in elasticity decrease during fruit softening. Among 6 apple cultivars, we got a high significant correlation between fruit firmness evaluated by Mageness-Taylor type device and that by laser Doppler vibrometry (LDV) in 4 cultivars. Methyl bromide treatment causes browning of interior flesh of apple. LDV could detect its interior defects. Pears like 'La France' showed biphasic decrease in elasticity during maturity after harvest, just like a kiwifruit. When the pears are stored under cold condition, the pattern of changes in elasticity reaches mono-phasic decrease. Usually when they are stored for 2 weeks under cold condition, the flesh becomes a characteristic melting texture that is most acceptable for consumers' favorite. LDV could not detect the melting texture during pear maturity. In order to detect the melting texture in pears, we developed a new versatile measuring system, called AMC (acoustic measurement of crispness). Vibration detected by the probe that is introduced into the flesh of fruits is monitored and transferred into frequency spectrum by fast Fourier transfer. AMC method could evaluate degree of crispness of fruits and it also detect the melting texture in pears and melon. Using principal component analysis, we tried to calculate the crispness from the data obtained by LDV method. Using pears as material, multiple regression analysis revealed that LDV data could detect the flesh quality such as melting texture.