Pomegranates

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Infobox on Pomegranates
Example of Pomegranates
Pomegranates.jpg
Freshness facts
Optimum carrying temperature 5°C for up to 2 months; longer storage should be at 7.2°C to avoid chilling injury
Highest freezing point -3°C
Acceptable product temp. at loading into containers Max. 5°C above carrying temperature
Optimum humidity 90%-95%
Ventilation setting for containers 10 m³/hr
Storage life 2-3 months
Climacteric / non-climacteric Non-climacteric
Ethylene production Low
Ethylene sensitivity Low
Modified / controlled atmosphere 5%-10% CO2; 3%-5% O2
Potential benefits Good
Availability
South America
Israel
Turkey
January - April
August - October
August - February

Pomegranates

Harvesting and handling

Pomegranates are yellow-green, brownish-yellow to purplish-red berries 5 - 12 cm in diameter with a smooth, leathery skin. Fruits are spherical, somewhat flattened, with a persistent calyx. The calyx may be 1-6 cm long. Numerous seeds are each surrounded by a pink to purplish-red, juicy, sub-acid pulp (arils) which is the edible portion. The pulp is somewhat astringent.

Pomegranates can be grown in tropical to warm temperate climates. However, the best quality pomegranate fruits are produced in regions with cool winters and hot, dry summers. Few areas are too hot and the pomegranate is more cold hardy (receives less damage) than citrus. The pomegranate is non-climacteric and can be left on the tree for some time after reaching maturity.

Fruit quality depends largely on sugar and acid content of the juice. A high quality pomegranate should also have an attractive skin, small seeds in the aril; and should be free from sunburn, growth cracks, cuts, bruises, and decay. Skin colour and smoothness are other quality indices. Sour and sour-sweet pomegranates have reddish skin, in contrast to sweet pomegranates, which have yellowish-green skin.

Cooling and storage

Harvested fruits have a low rate of respiration and of ethylene production. They are prone to moisture loss and should be stored at high humidity; this may be achieved by the use of polyethylene lined cartons. Chilling injury occurs if pomegranates are exposed for longer than one month at temperatures between their freezing point -3 °C and 5°C or longer than two months at 5° C. External symptoms include brown discoloration of the skin and increased susceptibility to decay. Internal symptoms include a pale colour of the arils (pulp around the seeds) and brown discoloration of the white segments separating the arils.

Internal breakdown is another physiological disorder in pomegranate fruit in which the pulp-bearing seeds (arils) do not develop their typical red colour and are somewhat flattened rather than plump.

CA conditions

Very few studies of the responses of pomegranates to CA have been conducted. Storage in 2% O2 reduces chilling injury if pomegranates are kept below 5°C. In one study, pomegranates were stored successfully at 6°C in 3% O2 + 6% CO2 atmosphere for 6 months. In another study a combination of 5% O2 + 15% CO2 was found to be effective in decay control and scald prevention for up to 5 months at 7°C.

Cautions

Pomegranates are very susceptible to water loss resulting in shrivelling of the skins. Storing fruit in plastic liners and waxing can reduce water loss, especially under conditions of lower relative humidity.

Storage disorders

Anthracnose, Aspergillus rot, Chilling injury, Coniella rot, Scald