Mechanical properties of fruit-cuticular membranes isolated from 27 cultivars of Diospyros kaki Thunb.

Fruit cuticular membranes (CMs) were isolated from 27 cultivars of Diospyros kaki Thunb., and relationships among their chemical compositions, densities and mechanical properties were analysed. Wide cultivar dependency was observed in both chemical compositions and mechanical properties, however, astringency did not show clear correlation with them. Densities of the CMs showed significant positive correlation with maximum stress and elastic modulus, but negative correlation with maximum strain. Positive correlations were also observed in elastic modulus-polysaccharide content and maximum strain-polysaccharide content, and negative correlation in elastic modulus-cutin content on a weight over unit area (μg/cm2) basis. The integration of densities of fruit CMs and their chemical constituents may explain the mechanical properties which are specific to each cultivar of D. kaki fruit.