Submitted to: Journal of American Society of Horticulture Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 24, 1997
Publication Date: N/A
Interpretive Summary: A major thrust of postharvest research is to reduce the use of fungicides in controlling decay and losses of fruit during storage. Previous research has shown that postharvest calcium maintains fruit firmness and reduces decay due to fungal pathogens. However, surface injury to the fruit resulting from calcium treatment has been a major obstacle to the commercial application of postharvest calcium treatment. We found that surface coating fruit after calcium treatments could eliminate injury resulting from some calcium treatments and reduce injury in other calcium treatments. Sequential treatments with calcium and fruit coatings also could significantly extend the postharvest life of the fruit relative to either treatment alone. This information provides apple growers and packinghouse operators with a new strategy to maintain the quality of apple fruit in storage while reducing their dependence on postharvest use of synthetic fungicides.
The effects of postharvest pressure infiltration of calcium chloride solutions, fruit coatings and shrink-wrap film treatments of 'Golden Delicious' apples 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. Calcium treatments (20 to 50 g/l) reduced internal and evolved ethylene and softening of fruits, but they also caused distinctive injury to the fruit surface. Following the calcium treatments with a water rinse and a wax- or shellac-based coating or a shrink-wrap film reduced surface injury in fruits treated with 35 or 50 g/l solutions of calcium chloride and eliminated injury resulting from a 20 g/l calcium chloride treatment. The fruit coatings delayed ripening; as indicated by 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 Calcium and a shrink-wrap film also reduced fresh mass loss, respiration and ethylene productions rates, but had no effect on other quality maintenance parameters tested. Internal carbon dioxide levels increased and oxygen and ethylene levels decreased in surface coated fruits during storage at 0 degrees C. Coating fruits without the use of calcium chloride also delayed ripening though not as well as that for fruits sequentially treated with calcium chloride and a surface coating.