Mandarins

Infobox on Mandarins
Example of Mandarins
Freshness facts
Optimum carrying temperature	4°C/8°C (Mandarins) 4°C/5°C (Clementines, Minneolas)
Highest freezing point	-1,1°C
Acceptable product temp. at loading into containers	Max. 5°C above carrying temperature
Optimum humidity	90%
Ventilation setting for containers	25 m³/hr
Storage life	1 to 2 months
Climacteric / non-climacteric	Non-climacteric
Ethylene production	Very Low
Ethylene sensitivity	Moderate
Modified / controlled atmosphere	0%-5% CO2; 5%-10% O2
Potential benefits	Slight
Availability
Australia/New Zealand South Africa South America	June - August April - June

Mandarins

Harvesting and handling

Soft citrus, easy peelers or mandarins are common names for a new series of citrus cultivars. Fruit of these cultivars are normally softer than the known citrus fruit and have a loose skin that can easily be removed giving rise to these names.

Some of the commercial cultivars that are exported are Clementines, Clemenules, Ellendales, Minneolas, Satsumas and Tangerines. Fruit of these cultivars are very delicate in texture and flavour and are more temperature sensitive than the traditional oranges. Cooling as soon as possible after harvest and maintenance of the cold chain throughout is very important to maintain quality. Different fungicides are recommended as post harvest treatments.

Degreening with ethylene (to remove the chlorophyll from the peel) may be necessary for some citrus fruit. However, this can increase susceptibility to decay. The degree of ripeness of citrus fruit is determined by the Brix value, which is a measure of the sugar/acid ratio of the fruit. Citrus fruit with a Brix value between 10 and 16 degrees have a good flavour. High quality mandarins will have a turgid, deep orange-red peel relatively free of blemishes. The fruit should be elliptical and firm. The peel should be easily removed from the flesh. The edible portion should be juicy and contain few or no seeds.

Cooling and storage

'Easy peelers' require adequate pre-cooling and continuous refrigeration at 4°C to 8°C and 90% relative humidity, under which conditions the fruit should keep for approx. 1-2 months. Storage duration depends on variety, maturity at harvest and decay control. Due to the high water content of this citrus fruit, a relative humidity of 90% is required. Inadequate ventilation may result in fermentation and rotting of the cargo as a result of CO₂ levels and inadequate supply of atmospheric oxygen.

Depending upon the species and variety, all citrus fruits are highly cold-sensitive. Grapefruit, lemons and limes are more susceptible to chilling damage than are oranges and mandarins, and late-ripening varieties are more temperature-sensitive than early varieties.

Chilling injury can occur in storage if temperatures fall <4°C/5°C. Chilling damage is manifested in citrus fruits in particular by spots on the peel (brown dots on the peel), accompanied by a bitter taste and unpleasant odour, rot and cell wall collapse. The glossiness of the peel is lost and the albedo layer (inner layer of the peel), which is normally white, turns a dark colour. When the fruit is divided up, the segments, which have a low juice content, break up and the whole fruit is glassy and soft. The severity of the chilling damage is determined not only by the extent to which the temperature has fallen beneath the limit, but also by the length of exposure to this temperature.

Excessively rapid warming of refrigerated fruit results in condensation and spoilage. Citrus fruit in storage should be examined often for pitting or decay. After such examinations, any decision on how long the fruit can safely be left in storage should be based on the fact that if pitting and decay are present, they will increase rapidly after the fruit are removed to higher temperatures.

Mixed loads

Citrus fruit should not be shipped with apples and not with ethylene emitting products (which might promote decay).

Cautions

O₂ below 5% can cause off-flavours. CO₂ greater than 5% can cause off-flavours. CA has not generally been found to benefit citrus fruit.

Storage disorders

Aging, Alternaria rot, Anthracnose, Aspergillus rot, Black mould rot, Black pit, Black spot, Blue mould, Brown rot, Canker, Chilling injury, Cottony rot, Degreening failure, Fusarium, Green mould rot, Grey mould rot, Insect damage, Melanose, Rind discoloration, Scab, Scald, Senescent breakdown, Sooty Blotch, Sooty Mould, Stem end rot.