Contribution of cellular structure to the large and small deformation rheological behavior of kiwifruit

Abstract

The relative contribution of turgor pressure, cell wall and middle lamellae to the rheology of kiwifruit was studied by performing large deformation assays and using an empirical model proposed by our group. Results were compared with those obtained previously through dynamic testing. Initial (σo) and residual relaxation (σ∞) stresses determined under 14% constant deformation correlated significantly with complex moduli (G*) and they allowed to detect incipient plasmolysis but not to determine the individual contributions of cell wall and middle lamellae to tissue elasticity. Firmness (Fm) showed no correlation with G* because measurement of failure stress required tissue damage but it was affected by ripening allowing to determine the individual contributions of cell wall and middle lamellae to its value.