The ultrastructure of the outer tissues of cold-stored apple fruits of high and low calcium content in relation to cell breakdown

The outer tissues of Cox's Orange Pippin apples from samples with initially high and low calcium content were examined in the electron microscope following 53, 81 or 99 days in air storage at 3 ^oC. Cell ultrastructure within tissues of both high and low calcium apples was comparatively normal in fruit stored for the shorter period but low calcium fruit showed symptoms of membrane breakdown after 81 days. The greatest structural differences were observed after storage for 99 days when low calcium fruits contained more cells exhibiting breakdown of membranes and organelles than high calcium apples and also showed more severe symptoms of cell wall breakdown.