Submitted to: American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 4, 1997
Publication Date: N/A
Interpretive Summary: Two major thrusts of postharvest research are to extend postharvest life of fresh produce and to reduce postharvest use of synthetic fungicides for controlling decay and losses of fresh produce during storage. We found that fruit coating but not film treatments applied at harvest delay fruit ripening like the more expensive commercial controlled atmosphere storage techniques plus modify the internal atmosphere of fruit in ways that naturally inhibit the growth of postharvest, decay-causing pathogens. The coating treatments also delay development of flavor-associated compounds indicating that coated fruit should be allowed to ripen before marketing for optimal flavor. This information provides apple growers and packinghouse operators with an alternative strategy to maintain the postharvest quality of apple fruit in storage while at the same time reducing their dependence on postharvest use of synthetic fungicides.
Technical Abstract: The effects of harvest-applied coating and shrink-wrap film treatments of apples (Malus xdomestica Borkh. 'Gala' and 'Golden Delicious') on volatile levels, quality attributes, respiration and internal atmospheres after storage at 0C for 1 to 6 months, and during subsequent ripening at 20C were investigated. Over thirty volatiles were detected, most of the identified volatiles were esters, the rest were alcohols, aldehydes, a ketone and a sesqueterpene. Fruit coatings transiently inhibited total volatile levels in 'Golden Delicious' while not affecting those in 'Gala' apples during 6 months of storage in air at 0C. Ripening fruit at 20C for up to three weeks following cold storage increased volatile levels with coated and untreated fruit having similar amounts. Only shellacked 'Golden Delicious' apples accumulated ethanol and ethyl acetate during ripening at 20C. The film treatment had no effect on fruit volatile levels during cold storage or during subsequent ripening at 20C. Coating but not film treatments reduced respiration and ethylene production rates that were observed upon transferring the fruit to 20C. Internal carbon dioxide and ethylene levels increased and oxygen levels decreased in coated fruit. The coating treatments led to better retention of fresh firmness in 'Golden Delicious' but not 'Gala' apples. Coating and film treatments reduced flesh mass loss in both cultivars during cold storage. The results suggest that harvest-applied coating and film treatments having relatively high permeability for carbon dioxide and oxygen and relatively low permeability for water vapors and fruit volatiles have potential for improving the storage and shelf-life qualities of 'Gala' and 'Golden Delicious' apples.