The effect of preharvest calcium sprays on quality attributes, physicochemical aspects of cell wall components and susceptibility to brown rot of peach fruits (Prunus persica L. cv. Andross)

This study was planned to evaluate the effect of preharvest calcium sprays on physicochemical aspects of cell wall components, activity patterns of pectin-modifying enzymes and susceptibility to brown rot (Monilinia fructicola) of peach fruits (Prunus persica L. cv. 'Andross'). Six or 10 preharvest calcium sprays were applied with two different formulas (calcium chloride and an ethylenediamine tetraacetic acid (EDTA) chelated calcium form) in equimolar calcium concentration (0.12% Ca, w/v). After harvest, peach fruits were cold stored (0 degrees C, 95% R.H.) up to 4 weeks. Calcium content increased significantly in the calcium-sprayed peaches both in the peel (25-42%) and in the flesh (11-17%), 1 d after harvest. Calcium chloride sprays were more effective than those of chelated calcium, whereas the increase of calcium content in the fruits seems to be unaffected by the 6 or 10 calcium sprays. The increase of cell wall calcium corresponded to increase of calcium in the insoluble pectin fraction, whereas no differences were detected in the calcium of water-soluble pectin fraction. Ethylene production, respiration rate, uronic acid content and activity of pectin-modifying enzymes did not indicate substantial differentiations by preharvest calcium sprays as ripening progressed after harvest or cold storage. Calcium sprays resulted in significant decrease of brown rot development, although no effect on disease incidence was recorded. (c) 2005 Elsevier B.V. All rights reserved.