(22) Evaluation of Postharvest Texture and Weight Loss in Apple Fruits by Destructive and Nondestructive Measurements

Abstract

The relation between sensory and instrumental measurements of apple texture was investigated to find an effective postharvest texture measurement method of apple. Then nondestructive evaluation of texture and weight loss using NIR was conducted. `Gala' and `Fuji' apples were sampled during storage at 20 °C with 80% to 85% relative humidity. Instrumental measurements included penetration, compression, and bending tests with a texture analyzer, and sensory attributes were finger firmness, hardness, crispness, and mealiness. The penetration test was more effective for postharvest texture measurement than compression and bending tests in the correlation between sensory texture and instrumental measurement. As texture evaluation parameters, elastic modulus (slope before rupture point) and work (area to penetrate) of penetration test were more sensitive than maximum force. Maximum force, generally used as the parameter for texture evaluation, had a little problem under influence of weight loss in `Fuji'; however, elastic modulus and work could detect the texture change of apple under influence of weight loss as well as softening. In the investigation of possibility of nondestructive evaluation using NIR of texture, the MLR analysis for elastic modulus determination of penetration test showed good correlation (R = 0.82, SEP = 2.66) in combination of two cultivars. Also, in the weight loss evaluation, MLR analysis showed the prediction correlation of 0.79 and SEP 1.08 in combination of two cultivars. These results showed the possibility of nondestructive evaluation using NIR of postharvest texture and weight loss.