University of California

Fruit English

Strawberry

Recommendations for Maintaining Postharvest Quality

strawberry062

Elizabeth J. Mitcham, Carlos H. Crisosto and Adel A. Kader
Department of Plant Sciences, University of California, Davis

Maturity & Quality

Maturity Indices

Based on berry surface color. US: minimum 1/2 or 3/4 berry surface showing red or pink color, depending on grade. Calif.: minimum 2/3 berry surface showing red or pink color.

Quality Indices

  • Appearance (color, size, shape, freedom from defects)
  • Firmness
  • Flavor (soluble solids, titratable acidity and flavor volatiles)
  • Nutritional value (Vitamin C)
  • For acceptable flavor, a minimum of 7% soluble solids and/or a maximum of 0.8% titratable acidity are recommended

Maturity & Quality Photos

strawberry_quality

Title: Quality

Photo Credit: Adel Kader, UC Davis 

strawberry_ripening_stages

Title: Ripening Stages

Photo Credit: Don Edwards, UC Davis

Temperature & Controlled Atmosphere

Optimum Temperature

0 ± 0.5°C (32 ± 1°F)

Optimum Relative Humidity

90 to 95%

Rates of Respiration

Temperature 0°C (32°F) 10°C (50°F) 20°C (68°F)
ml CO2/kg·hr 6-10 25-50 50-100

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.

Rate of Ethylene Production

2H4/kg·hr at 20°C (68°F)

Response to Ethylene

Strawberries do not respond to ethylene by stimulation of ripening processes (strawberries should be harvested near to full ripe). Removal of ethylene from storage air may reduce disease development.

Responses to Controlled/Modified Atmospheres

Modified atmosphere packaging for shipment with 10 to 15% carbon dioxide reduces the growth of Botrytis cinerea (Grey Mold Rot) and reduces the respiration rate of the strawberries thereby extending postharvest life. Use of whole pallet covers for modified atmospheres is the most common method.

Temperature & Controlled Atmosphere Photos

strawberry_temperature_effects

Title: Temperature Effects

Photo Credit: Don Edwards, UC Davis

Disorders

Physiological and Physical Disorders

Perhaps because of rapid marketing and very short storage periods, physiological disorders are not a major concern with strawberry fruit.

Pathological Disorders

Diseases are the greatest cause of postharvest losses in strawberries. Postharvest fungicides are not used on strawberries; therefore, prompt cooling, storage at 0°C (32°F), preventing fruit injury, and shipment under high carbon dioxide are the best methods for disease control. In addition, care should be taken to keep diseased or wounded berries out of trays at harvest as strawberry diseases will spread from diseased to nearby healthy berries (nesting).

Irradiation has been tested on strawberries for decay control with mixed success. Doses needed for adequate decay control without high carbon dioxide generally result in excessive berry softening.

Botrytis Rot (Grey Mold). Caused by Botrytis cinerea is the greatest cause of postharvest strawberry losses. This fungus continues to grow even at 0°C (32°F), however growth is very slow at this temperature.

Rhizopus Rot. Caused by the fungus Rhizopus stolonifer. Spores of this fungus are usually present in the air and are easily spread. This fungus will not grow at temperatures below 5°C (41°F), therefore temperature management is the simplest method of control.

figure-1

Figure 1. Cooling and deterioration. Strawberries should be cooled as soon as possible after harvest; delays beyond 1 hour reduce the percentage of marketable fruit.

[For more information, see our publication “Handling Strawberries for Fresh Market”, available for purchase using our Order Form.

Disorders Photos

strawberry_abrasion_damage

Title: Abrasion Damage

Photo Credit: Don Edwards, UC Davis

strawberry_anthracnose

Title: Anthracnose

Photo Credit: Don Edwards, UC Davis

strawberry_botrytis_rot

Title: Botrytis Rot (1)

Photo Credit: Don Edwards, UC Davis

strawberry_botrytis_rot2

Title: Botrytis Rot (2)

Photo Credit: Don Edwards, UC Davis

strawberry_leather_rot1

Title: Leather Rot (1)

Photo Credit: Don Edwards, UC Davis

strawberry_leather_rot2

Title: Leather Rot (2)

Photo Credit: Don Edwards, UC Davis

strawberry_mechanical_damage

Title: Mechanical Damage Followed by Decay

Photo Credit: Adel Kader, UC Davis 

strawberry_mucor_rot1

Title: Mucor Rot (1)

Photo Credit: Don Edwards, UC Davis

strawberry_mucor_rot2

Title: Mucor Rot (2)

Photo Credit: Don Edwards, UC Davis

strawberry_rhizopus_rot

Title: Rhizopus Rot

Photo Credit: Don Edwards, UC Davis

strawberry_grey_mold

Title: Strawberry Gray Mold

Photo Credit: Adel Kader, UC Davis 

Date

August 1996

Use of Materials

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Except for these specified uses, no part of the textual materials available on the UC Postharvest Technology Center Web site may be copied, downloaded, stored in a retrieval system, further transmitted or otherwise reproduced, stored, disseminated, transferred or used, in any form or by any means, except as permitted herein or with the University of California's prior written agreement. Request permission from UC Postharvest Technology Center. Distribution for commercial purposes is prohibited.

Links to any of these UC Postharvest Technology Center pages are permitted, but no endorsement of the linking site or products mentioned in the linking page is intended or implied by such a link.

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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