Recommendations for Maintaining Postharvest Quality
Maturity & Quality
Temperature & Controlled Atmosphere
Optimum Temperature0 ± 1°C (32 ± 2°F)
Cool rapidly, this apple softens quickly.
Optimum Relative Humidity
90 to 95%
Rates of Respiration
6.5 to 8 ml/kg·hr at 0°C (32°F)
To calculate heat production multiply ml CO2/kg·hr by 440 to get Btu/ton/ day or by 122 to get kcal/metric ton/day.
Rates of Ethylene Production
4 to 12 µl/kg·hr at 0°C (32°F)
Responses to Ethylene
Responses to Controlled Atmospheres (CA)
The following atmospheres have been successful for Gala apples: 1 to 2% carbon dioxide (1.5 to 2% oxygen)
Additional research may determine more optimum atmospheres.
Physiological and Physical Disorders
Storage Scald. Information is incomplete; however, Gala appears to be slightly to moderately susceptible to scald. DPA may be needed for storage in air for longer than 2 months. CA storage reduces scald incidence.
Bitter Pit. Bitter pit has been observed on Gala apples. Large fruit from young, vigorous trees are most susceptible. Preharvest calcium sprays are most effective to reduce bitter pit. Postharvest calcium dips are also beneficial.
Calcium rates for postharvest dips:
Gray Mold, Blue Mold.
Mucor rot. Some orchards have Mucor fungus in the soil. Sanitation to keep soil out of drench water is important. Do not place fruit from the orchard floor into storage bins. Chlorine will not effectively control this organism and there are no effective fungicides. Mucor continues to grow slowly even at 0°C (32°F).
Sanitation of Water Systems
Sanitation of water systems used to handle apples is important to prevent spread of disease organisms to healthy fruit. Chlorine at 50 to 100 ppm is very effective but the level of available chlorine and solution pH (7.0) must be monitored frequently and adjusted. Sodium will accumulate when liquid sodium hypochlorite is used and can burn apple tissues. We recommend water systems be changed once a day to reduce the risk of burn to apple skins. Gala is very sensitive to sodium burn.
[For more information, see our publication "Fruit Ripening and Ethylene Management" available for purchase using our Publication order form.]
DateNovember 1995/July 1997
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How to Cite
Author(s) names. Initial publication or update date (located at the top). Title. Link to the specific Produce Fact Sheet webpage (Accessed date)
Example: Cantwell, M. and T. Suslow. 2002. Lettuce, Crisphead: Recommendations for Maintaining Postharvest Quality.