Mechanisms of texture and cell microstructure changes during post-ripening of ‘Cuixiang’ kiwifruit

The lack of ability to control post-ripening softening is a bottleneck that affects the economic efficiency of 'Cuixiang' kiwifruit. This study investigated the softening mechanisms of fruit texture and microstructural changes during post-ripening at room temperature and established a kinetic model to predict and validate shelf life. The starch content of 'Cuixiang' decreased, total soluble solid (TSS) and sugar–acid ratio (SAR) increased, and the texture gradually became softer during post-ripening. Microstructural changes reflected starch fragmentation and disintegration, cell structure collapse, plasmolysis, and intensified mitochondrial vacuolization and cell-wall degradation during post-ripening. Changes in cell wall polysaccharide fractions and the evolution of cell membrane lipid metabolism indicated that post-ripening was accompanied by cellulose and hemicellulose degradation. In addition, pectin components transformed into water-soluble pectin, and oxidative stress across the cell membrane caused membrane damage and rupture, increasing membrane permeability. A zero-order kinetic model of firmness was selected to accurately and reliably predict the shelf life of 'Cuixiang' kiwifruit.