Physiological changes associated with fruit ripening and the development of mealy texture during storage of nectarines

Abstract Ripening of nectarines (Prunus persica) has been studied using a whole cell approach. Adhesion between cells was measured by the application of tensile tests to plugs of mesocarp tissue, followed by the examination of the fracture surface using Low Temperature Scanning Electron Microscopy. Other physical attributes of the nectarine tissue that were measured include 1 the propensity with which cells rupture in hypotonic solutions, 2 tissue density and the volume of airspace, and 3 the water potential, osmotic potential and turgor pressures. Nectarines coolstored at 0°C for 0 and 4 weeks remained juicy when ripe, whilst nectarines coolstored for 7 weeks ripened abnormally, developing a dry and mealy texture. During ripening, adhesion between cells decreased, turgor pressures decreased, and propensity of cells to rupture increased. These changes occurred in both non-mealy and mealy nectarines from all storage regimes. The principle differences between non-mealy and mealy nectarines was the presence or absence of juice on the fracture surface following the application of tensile tests, and higher%airspace in tissue from abnormally ripened fruit. It is suggested that the processes leading to the hydration and exudation of juice onto the cell wall surfaces are important for texture of ripening nectarines.