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Lemon

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

Ask the Produce Docs for this Commodity

Publications for this Commodity

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

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

Date

May 1999

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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.

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

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