Nondestructive And Destructive Measurement Of Texture Changes Of Postharvested Apple Fruits

Texture changes of Fuji and Gala apples were studied using nondestructive acoustic impulse response technique, background color measurement, conventional destructive measurement and sensory evaluation. Values of those main quality parameters of Fuji and Gala apples were measured with different methods, the validity of those methods for detecting fruits texture changes were also compared. Some quality standards of the postharvested Fuji and Gala apples were suggested.1. Experiment parameters of SD150 dynamic test and signal analyzing system were established, and the quality changes of Fuji and Gala apples were studied using acoustic impulse response technique, puncture test of texture analyzer and background color measurement. It was found the acoustic impulse response technique could reflect changes of fruit stiffness as other methods, which proved its validity in detecting fruits texture state.2. Texture changes of postharvested Fuji and Gala apples were measured using texture profile analysis test of the texture analyzer. Correlation coefficients between values of those texture parameters were also analyzed. Values of fruits adhesiveness showed negative correlation with hardness, fracturability, cohesiveness and other parameters respectively; there were good correlations between cohesiveness and hardness, resilience, chewiness respectively ( R = 0.86 ~ 0.95 ); values of resilience correlated well with those parameters excluding of the adhesiveness and the springiness (R = 0.67 ~ 0.95 ). It was concluded that parameters of fracturability, adhesiveness, cohesiveness, resilience and chewiness may gave reliable values in respect of texture properties of apple fruits. Texture of Gala apples are more likely to become mealiness than that of Fuji apples.3. Nondestructive acoustic impulse response test, destructive test of penetration, puncture test and TPA test of the texture analyzer for measuring fruit texture were compared. The reproducibility of the nondestructive test was found to be the best, and its sensitivity to detect firmness changes was better than that of the destructive methods used. Values of the nondestructive stiffness coefficient correlated well with those destructive parametersconventionally tested. Correlation coefficient was higher between values of stiffness coefficient and force of the penetrometer, puncture Fmax , modulus of elasticity, hardness of the TPAtest respectively for Fuji apples (R2> 0.80 ).4. Some quality parameters of Fuji and Gala apples were measured with destructive and nondestructive test. It was found stiffness coefficient of fresh harvested Fuji and Gala apples mostly distributed at 24.0 ~ 26.0 kHz2g2/3 and 24.0 ~ 25.2 kHz2g2/3 respectively; Hue angle of the fruits background skin color mostly distributed at 103.5~ 105.0 and 95.0 ~ 100.0 respectively. Models of stiffness coefficient and storage time, models of hue angle and storage time were established which were based on stiffness and background color changes of the fruits. Sensory evaluations were combined with those measurements and some quality standards of Fuji and Gala apples for sale were suggested.