Mandarin

Maturity and Quality

Maturity Indices

Color (yellow, orange, and/or red) on 75% of fruit surface and soluble solids/acid ratio of 6.5 or higher.

Quality Indices

Color intensity and uniformity
Size
Shape
Firmness
Freedom from decay
Freedom from defects including freezing injury, chilling injury, insect damage, and scars
Flavor depends upon soluble solids/acid ratio and absence of off-flavors

Postharvest Handling and Storage

Optimum Temperature

5-8°C (41-46°F) for 2 to 6 weeks, depending on cultivar, maturity-ripeness stage at harvest, and decay control treatments used.

Rates of Respiration

Temperature	5°C (41°F)	10°C (50°F)	15°C (59°F)	20°C (68°F)
ml CO2/kg·hr	2-4	3-5	6-10	10-15

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.

Responses to Ethylene

Mandarins and tangerines can be degreened by exposure to 1-10 ppm ethylene for 1-3 days at 20 to 25°C (68 to 77°F)
Removal of ethylene from transport vehicles and storage facilities for citrus fruits can help reduce decay incidence

Optimum Relative Humidity

90-95%

Responses to Controlled Atmospheres (CA)

A combination of 5-10% O2 and 0-5% CO2 can delay color changes from green to yellow and other symptoms of senescence, but it is not very effective in decay control. Mandarins do not tolerate exposure to fungistatic CO2 levels (10-15%). Commercial use of CA is very limited.

Temperature & Controlled Atmosphere Photos

Title: Degreening

Photo Credit: Irv Eaks, University of California, Riverside

Disorders

Physiological and Physical Disorders

Chilling injury. Symptoms include pitting and brown discoloration followed by increased susceptibility to decay. Severity increases with longer exposures to lower temperature below 5°C (41°F).

Oil spotting (Oleocellosis). Harvesting and handling turgid citrus fruits can result in breaking of oil cells and release of oil that damages surrounding tissues.

Aging. Symptoms include shriveling and peel injury around the stem end.

Pathological Disorders

Major Diseases:

Green mold (Penicillium digitatum)
Blue mold (Penicillium italicum)
Phomopsis stem-end rot (Phomopsis citri)
Stem end rot (Lasiodiplodia theobromae)
Brown rot (Phytophthora citrophthora)
Anthracnose (Colletotrichum gloeosporioides)

Control Strategies

Reduce the pathogen population in the environment:

Effective preharvest disease control
Use of chlorine in wash water
Heat treatments
Effective sanitation procedures

Maintain Fruit Resistance to Infection