Garlic

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Infobox on Garlic
Example of Garlic
Garlic.jpg
Freshness facts
Optimum carrying temperature -1°C to 0°C
Highest freezing point -
Acceptable product temp. at loading into containers Max. 2°C above carrying temperature
Optimum humidity <75%
Ventilation setting for containers 10 m³/hr
Storage life 6 to 9 months
Climacteric / non-climacteric Non-climacteric
Ethylene production Very low
Ethylene sensitivity Low
Modified / controlled atmosphere 1-2% O2; 10% CO2
Potential benefits Good
Availability
South America
Asia
December-April
July-October

Harvesting and Handling

Garlic is a member of the onion family. It is a bulb comprised of cloves, individually wrapped in dried leaf sheaths or skins attached to a compressed stem plate. The whole bulb is also wrapped in several layers of dried leaf sheaths. Garlic can be harvested at different stages of development for specialty markets, but most garlic is harvested when the bulbs are well mature. Harvest occurs after the tops have fallen and are very dry.

High quality garlic bulbs are clean, white (or other colours typical of the variety), and well cured (dried neck and outer skins). The cloves should be firm to the touch. Outer cloves of bulbs are easily damaged during mechanical harvest and these damaged areas discolour and decay during storage. Curing garlic is the process by which the outer leaf sheaths and neck tissue of the bulb are dried. Warm temperatures, low RH, and good airflow are conditions needed for efficient curing. Under favourable climatic conditions, garlic is usually cured in the field. After harvest and trimming it may remain in bins in the field to cure further. Curing is essential to obtain maximum storage-life and have minimal decay.

Cooling and Storage

Well cured garlic has a very low respiration rate and it is typically cooled when placed in storage. High initial airflow may be used to bring pulp temperature down rapidly to storage temperature.

The variety of garlic affects potential storage life, and the recommended conditions for commercial storage depend on the expected storage period. Garlic can be kept in good condition for 1-2 months at ambient temperatures (20°-30°C) under low relative humidity (<75%). However under these conditions, bulbs will eventually become soft, spongy and shrivelled due to water loss. For long-term storage, garlic is best maintained at temperatures of -1°C to 0°C with low relative humidity (60-70%). Good airflow is also necessary to prevent any moisture accumulation. Under these conditions garlic can be stored for more than 9 months.

Relative humidity should be lower than for most vegetables because high humidity causes root and mould growth. Garlic will eventually lose dormancy, signalled by internal development of the sprout. This occurs most rapidly at intermediate storage temperatures of 5° to 18°C. Garlic odour is easily transferred to other products and should be stored separately. High humidity in the storages will favour mould growth and rooting. Mould growth can also be problematic if the garlic has not been well cured before storing.

For long-term storage, garlic should have no or minimal internal sprout growth and should be well cured. To control sprout development and lengthen the storage period, garlic may be treated with pre-harvest applications of sprout inhibitors, such as maleic hydrazide, or be irradiated after harvest. Garlic is not chilling sensitive and optimum storage temperature of -1°C is well above the freezing point of garlic, such depending on seasonal period, i.e. late(r) season garlic is more cold tolerant.

Controlled atmosphere considerations

Atmospheres with high CO2 are beneficial in retarding sprout development and decay during storage at 0°C to 5°C. Low O2 alone does not retard sprout development.

Storage disorders

Bacterial soft rot, Basal rot, Black mould rot, Blue mould, Downy mildew, Fusarium, Grey mould rot, Macrophomina rot, Blotch, White rot.