University of California

Fruit English

Apple, Granny Smith

Recommendations for Maintaining Postharvest Quality

Apple, Granny Smith; Manzana, Granny Smith; Pomme, Granny Smith

Elizabeth J. Mitcham, Carlos H. Crisosto and Adel A. Kader

Department of Plant Sciences, University of California, Davis

Maturity & Quality

UC

Maturity Indices

Average starch score for a sample of 30 apples equal to or greater than 2.5 on a 0 to 6 scale, based on the percentage of the core and cortex areas stained dark blue when dipped in the iodine - potassium iodide solution.**

Quality Indices
  • Flavor, including soluble solids (12% or higher), titratable acidity (0.75% or lower) and flavor volatiles
  • To improve eating quality, early season fruit can be conditioned with an ethylene treatment at 100 ppm for 24 hours at 20°C (68°F) for immediate marketing
  • Freedom from defects such as bruising, stem or blossom-end cracks, bitter pit, insect injury and watercore
  • Deep green color and absence of blush and/or sunburn (yellow or brown spots)

Maturity & Quality Photos

apple_grannysmith_starch2218x1721

Title: Granny Smith Apple Starch Scale

Photo Credit: Don Edwards, UC, Davis

Temperature & Controlled Atmosphere

Optimum Temperature
0.5 ± 0.5°C (33 ± 1°F); highest freezing point is -1.5°C (29.3°F).

Some reports indicate that 0°C (32°F) can result in low temperature (chilling) injury in some seasons.

Optimum Relative Humidity

90-95%

Rates of Respiration

2 to 4 ml/kg·hr at 0.5 °C (33°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

1 to 6 µl/kg·hr at 0.5°C (33°F)

Responses to Ethylene
  • Ethylene can accelerate senescence and loss of firmness
  • Removal of ethylene may reduce susceptibility to scald
Responses to Controlled Atmospheres (CA)

The following atmosphere has been successful for Granny Smith apples: 1.5% oxygen + 1.0% carbon dioxide.

  • Maintains firmness and titratable acidity
  • Reduces susceptibility to bitter pit and storage scald

Disorders

Physiological and Physical Disorders

Storage Scald. Granny Smith apples are very susceptible to storage scald especially when grown in hot dry climates such as much of California. Diphenylamine (DPA) drench before storage is recommended, especially for storage beyond 3 months. CA storage can reduce scald incidence and severity, and reducing ethylene levels in storage also reduces scald development. The lower the oxygen concentration used, the better the scald control (be sure to determine fruit tolerance to low oxygen first). Oxygen at 0.7% may give good scald control. Early season or low maturity fruit is more susceptible to scald.

Bitter Pit. Granny Smith apples are very susceptible to bitter pit. 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:

  • 3 to 4% - solid flakes (77% CaCl2)
  • 2 to 3% - calcium chloride (CaCl2)
  • 0.7 to 1% -calcium ion (Ca+2)
Pathological Disorders

Gray Mold, Blue Mold. These decay-causing pathogens can be controlled by avoiding fruit injury, sanitizing water systems with chlorine and cooling fruit quickly.

Mucor rot. Some orchards have Mucor organisms in the soil. Sanitation to keep soil out of drench water is important. Do not place fruit from orchard floor into storage bins. Chlorine will not control this organism and there are no effective fungicides. Mucor continues to grow slowly even at 0°C (32°F).

Disorders Photos

apple_grannysmith_bitterpit1023x669

Title: Bitter Pit

Photo Credit: Don Edwards, UC, Davis

apple_grannysmith_bluemold

Title: Blue Mold

Photo Credit: Don Edwards, UC, Davis

apple_fuji_bluemold

Title: Blue Mold

Photo Credit: Don Edwards, UC, Davis

apple_grannysmith_burn_skins700x462

Title: Burn to Apple Skins

Photo Credit: Don Edwards, UC, Davis

apple_grannysmith_dpa

Title: Biphenylanime (DPA)

Photo Credit: Don Edwards, UC, Davis

apple_grannysmith_graymold700x462

Title: Gray Mold

Photo Credit: Don Edwards, UC, Davis

apple_grannysmith_Scald2_700x464

Title: Scald (1)

Photo Credit: Don Edwards, UC, Davis

apple_grannysmith_Scald2_700x464

Title: Scald (2)

Photo Credit: Don Edwards, UC, Davis

apple_grannysmith_storagescald732x483

Title: Storage scald

Photo Credit: Don Edwards, UC, Davis

apple_grannysmith_sunburn732x483

Title: Sunburn

Photo Credit: Don Edwards, UC, Davis

apple_grannysmith_WaterCore1_685x450

Title: Watercore (1)

Photo Credit: Don Edwards, UC, Davis

apple_grannysmith_WaterCore2_700x465

Title: Watercore (2)

Photo Credit: Don Edwards, UC, Davis

apple_grannysmith_watercore3

Title: Watercore (3)

Photo Credit: Don Edwards, UC, Davis

 

Sanitation of Water Systems

Sanitation of water systems used to handle apples is important. Chlorine at 50 to 100 ppm is very effective but the level of residual 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 prevent burn to apple skins. Granny Smith is moderately sensitive to sodium burn.

*Available from: Fruit and Vegetable Quality Control Calif. Dept. of Food and Agriculture 1220 N Street, Rm. A-265 Sacramento, CA 95814 (916)654-0919 FAX (916)654-0666.

** Preparation of Iodine-Potassium Iodide (I2KI) Solution for Starch Staining: Dissolve 58.1 g of potassium iodide (KI) in about 150 ml of distilled water, then add 14.5 g iodine (I2) and mix well until completely dissolved. Then complete the final volume to 2 liters with distilled water. Store in a brown bottle or aluminum foil covered bottle.

[For more information, see our publication "Fruit Ripening and Ethylene Management", available for purchase using our Publication order form.]

Date

February 1996

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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. 

http://ucanr.edu/sites/Postharvest_Technology_Center_/Commodity_Resources/Fact_Sheets/Datastores/Vegetables_English/?uid=19&ds=799 (Accessed January 18, 2014).

College of Agricultural & Environmental Sciences
Postharvest Technology Center
Department of Plant Sciences

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