University of California

Fruit Produce Facts English

Return to Fact Sheet


Recommendations for Maintaining Postharvest Quality


Mary Lu Arpaia1 and Adel A. Kader2

1Dept. of Botany and Plant Sciences, Univ. of California, Riverside

2Department of Plant Sciences, University of California, Davis

Maturity & Quality
Maturity Indices

A minimum juice content by volume of 28 or 30% depending on grade; color lemons picked at the dark-green stage have the longest postharvest life while those picked fully-yellow must be marketed more rapidly.

Quality Indices
  • Yellow color intensity and uniformity
  • Size
  • Shape
  • Smoothness; firmness
  • Freedom from decay
  • Freedom from defects including freezing damage, drying, mechanical damage, rind stains, red blotch, shriveling, and discoloration
Temperature & Controlled Atmosphere
Optimum Temperature

12-14°C (54-57°F) depending on cultivar, maturity-ripeness stage at harvest, production area, and duration of storage and transport (can be up to 6 months).

Optimum Relative Humidity


Rates of Respiration
Temperature 10°C (50°F) 15°C (59°F) 20°C (68°F)
ml CO2/kg·hr 5-6 7-12 10-14

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
Responses to Ethylene

If degreeing is desired, lemons can be treated with 1-10 ppm ethylene for 1-3 days at 20 to 25°C (68-77°F), but this exposure may accelerate deterioration rate and decay incidence

Responses to Controlled Atmospheres (CA)

CA of 5-10% O2 and 0-10% CO2 can delay senescence including loss of green color of lemons. Fungistatic CO2 levels (10-15%) are not used because they may induce off-flavors due to accumulation of fermentative volatiles, especially if O2 levels are below 5%. Removal of ethylene from lemon storage facilities can reduce rate of senescence and decay incidence.

Physiological and Physical Disorders

Chilling injury. Symptoms include pitting, membranous staining, and red blotch. Severity depends upon cultivar, production area, harvest time, maturity-ripeness stage at harvest, and time-temperature of postharvest handling operations. Moderate to severe chilling injury is usually followed by decay.

Oil spotting (Oleocellosis). Breaking of oil cells due to physical stress on turgid fruits causes release of the oil that damages surrounding tissues. Avoiding harvesting lemons when they are very turgid and careful handling reduce severity of this disorder.

Pathological Disorders

Green mold. Caused by Penicillium digitatum which penetrates the fruit rind through wounds. Symptoms begin as water-soaked area at the fruit surface followed by growth of colorless mycelium, then sporulation (green color).

Blue Mold. Caused by Penicillium italicum which can penetrate the uninjured peel and can spread from one lemon to adjacent lemons. Symptoms are similar to green mold except that the spores are blue.

Altenaria rot. Caused by Alternaria citri which enters the lemons through their buttons. Preharvest treatment with gibberellic acid or postharvest treatment with 2,4-D delay senescence of the buttons and subsequent decay by Alternaria.

Control Strategies
  • Careful handing during harvesting and handling to minimize cuts, scratches, and bruises
  • Treatment with postharvest fungicides and/or biological agents
  • Prompt cooling to the proper temperature range
  • Maintaining optimum ranges of temperature and relative humidity and exclusion of ethylene during transport and storage
  • Effective sanitation throughout the handling system

Disorders Photos

Title: Oil Spotting (1)

Photo Credit: Irv Eaks

Title: Oil Spotting (2)

Photo Credit: Irv Eaks

Title: Sclerotinia Rot

Photo Credit: Don Edwards, UC Davis


May 1999

Use of Materials

The UC Postharvest Technology Center grants users permission to download textual pages (including PDF files) from this World Wide Web site for personal use or to reproduce them for educational purposes, but credit lines and copyright notices within the pages must not be removed or modified.

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.

The information in this fact sheet represents our best understanding of the current state of knowledge at the time of the latest update, and does not represent an exhaustive review of all research results. 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. (Accessed January 18, 2014).

Top of page



Webmaster Email: