Studies on Firmness Measurement of Fruit by Impact Force

Abstract

The impact force of fruit falling on a flat plate was investigated as a means for quick and nondestructive quality detection. Dependence of the impact force on mass, impact velocity and mechanical properties of the fruit were shown theoretically. A method of calculating a parameter which indicates the fruit firmness was proposed. It is calculated from the impact force and mass of the fruit. It is not necessary to determine the impact velocity. Experiments were made on kiwifruit. The impact forces at various stages of maturity were measured and analyzed. Simultaneously firmness was measured by a nondestructive fruit firmness meter. Sugar content and titratable acidity were also measured. The relationships between the firmness index obtained from the impact force and the other measurements were shown.