Mechanical properties of kiwifruit as influenced by water loss, location, and compression velocity with respect to compression damage

Abstract

International distribution of kiwifruit to overseas markets often results in high loads being applied to the fruit for a prolonged time. These high loads may cause compression damage. Compression damage refers to the permanent deformation of near-surface tissue. Kiwifruit affected by compression damage are less attractive to consumers and might result in further deterioration of the fruit. Previous research has been done to model the behaviour of kiwifruit under compression loads and predict compression damage susceptibility. Nevertheless, there is limited understanding of the influence of fruit water loss, compression location and velocity on kiwifruit mechanical properties. In this article, we demonstrate that Young modulus decreases 10-fold during kiwifruit storage (from about 3 MPa to 0.3 MPa). Additionally, kiwifruit of the same flesh firmness and different water loss can present a 2-fold difference in Young's modulus value, with lower values towards the higher water loss. Furthermore, small increase in compression velocity (0.01–0.08 mms−1) led to 2-fold decrease in Young's modulus values. Also, the stem end was found to have a slightly but significantly higher Young's modulus value than the middle of the fruit and the blossom end for soft fruit. These dependencies prove the complexity of the kiwifruit compression damage behaviour and the importance of improvement of the currently existing models.