University of California

Fruit English

Lemon

Recommendations for Maintaining Postharvest Quality

Lemon

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

90-95%

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.

Disorders

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

lemon_oil_spotting

Title: Oil Spotting (1)

Photo Credit: Irv Eaks

lemon_Oil_Spotting2

Title: Oil Spotting (2)

Photo Credit: Irv Eaks

lemon_Sclerotinia_Rot

Title: Sclerotinia Rot

Photo Credit: Don Edwards, UC Davis

Date

May 1999

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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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