Effects of postharvest calcium and fruit coating treatments on postharvest life, quality maintenance, and fruit-surface injury in 'Golden Delicious' apples

The effects of postharvest pressure infiltration of calcium chloride (CaCl2) solutions, fruit coatings and shrink-wrap film treatments of apples (Malus domestica Borkh. 'Golden Delicious') on peel injury, quality attributes, respiration and internal atmospheres after storage at 0 degrees C for 2 to 6 months, and during subsequent ripening at 20 degrees C were investigated. CaCl2 treatments (0.14 to 0.34 mol.L-1) reduced internal and evolved ethylene and softening of fruits, but they also caused distinctive injury to the fruit surface. Following the CaCl2 treatments with a water rinse and a wax-or shellac-based coating or a shrink-wrap film reduced surface injury in fruits treated with 0.24 or 0.34 mol.L-1 solutions of CaCl2 and eliminated injury resulting from a 0.14 mol.L-1 CaCl2 treatment. The fruit coatings delayed ripening; as indicated hy better retention of fresh mass, green peel color, titratable acidity and flesh firmness, and the reduced respiration and ethylene production rates that were observed upon transferring the fruits to 20 degrees C. Sequential treatments with CaCl2 and a shrink-wrap film also reduced fresh mass loss, respiration and ethylene production rates, but had no effect on other quality characteristics. Internal CO2 levels increased and O-2 and ethylene levels decreased in surface coated fruits during storage at 0 degrees C. Coating fruits without the use of CaCl2 also delayed ripening though not as well as that for fruits sequentially treated with CaCl2 and a surface coating.