Artichoke

Infobox on Artichoke
Example of Artichoke
Freshness facts
Optimum carrying temperature	0°C / +1°C
Highest freezing point	-1,2°C
Acceptable product temp. at loading into containers	Max. 2°C above carrying temperature
Optimum humidity	>95%
Ventilation setting for containers	10 m³/hr
Storage life	3-7 weeks
Climacteric / non-climacteric	Non-climacteric
Ethylene production	Very low
Ethylene sensitivity	Low
Modified / controlled atmosphere	2%-3% O2; 2%-5% CO2
Potential benefits	Moderate
Availability
Cyprus Egypt France Greece Israel Italy Lebanon Morocco Spain UK	November - May December - April March - November April - May January - March December - May May - August December - May November - June March - May

Artichoke

Harvesting and Handling

The artichoke, of Mediterranean origin, is a thistle-like vegetable (edible artichoke) of the composite-flower family.

The flower heads of the artichoke plant, which grow at the ends of long stalks, reach a diameter of approx. 5 - 15 cm. They consist of a very fleshy bottom part and bracts which overlap one another like roof tiles. Only the bottom part and the lower, likewise very fleshy parts of the bracts are eaten. Artichoke colour differs according to variety and ranges from whitish through green to purple. Its slightly bitter flavour (caused by the bitter substance cynarin) and high vitamin content make the artichoke a delicacy.

Artichokes have to be harvested before the flowers open and the blue petals become visible. A high quality artichoke will have tightly closed, turgid outer bracts without signs of black tip, blistering or browning. They should be medium to dark glossy green in colour and some cultivars may have a magenta colour at the base of each bract. The artichoke should not be soft when squeezed and feel heavy for their size. Both thorny and thornless cultivars are used commercially.

Open bracts are an indication that the artichoke is already overripe and quality will very quickly degrade. Artichokes in this condition are no longer suitable for transport. In addition, brown discoloration (of white and green varieties) and dry leaf tips indicate that the artichokes have been stored for too long and their quality has therefore started to degrade. There should be no water or dew between the individual bracts, since moisture encourages mould growth.

Because of its considerable impact- and pressure-sensitivity, packages of this cargo must be secured in such a way that they are prevented from damaging each other. Spaces between packages or pallets must be filled, to prevent slippage or tipping. Moisture loss can be minimized by cooling adequately and packing artichokes in waxed cartons or in cartons lined with perforated plastic film.

Splitting of the bract tip is a common problem caused by rough handling during and after harvest. The surfaces of bracts are also easily bruised and scratched. The abraded areas usually turn brown or black, which greatly detracts from appearance and quality, and provide a route through which microorganisms can enter.

Cooling and Storage

In order to maintain quality and storage-life, artichoke buds should be pre-cooled to below 5°C within 24 hours of harvest. Hydro-cooling, forced-air cooling and package-icing are common methods of postharvest cooling of artichokes and will generally retard deterioration such as discolouration, weight loss and decay.

Freezing injury will be initiated at - 1.2°C. Symptoms of light freezing injury are blistering of the cuticle and a bronzing of the outer bracts. This may occur in the field with winter harvested buds and is used in marketing as an index of high quality. More severe freeze injury results in watersoaked bracts and the heart becoming brown to black and gelatinous in appearance over time.

Artichokes are living organs in which respiration processes predominate, because their supply of new nutrients has been cut off by separation from the parent plant.

Care of the cargo during the voyage must be aimed at controlling respiration processes (release of CO₂, water vapour, ethylene and heat) in such a way that the cargo is at the desired stage of ripeness on reaching its destination. Inadequate ventilation may result in fermentation and rotting of the cargo as a result of increased CO₂ levels and inadequate supply of atmospheric oxygen

Mixed loads

Artichokes can be shipped in mixed loads at 0° to 5°C for durations shorter than two weeks.

Controlled atmosphere considerations

Controlled or modified atmospheres show moderate to little benefit to sustaining artichoke quality when stored at 0°C. Conditions of 2%-3% O₂ and 2%-5% CO₂ delay discolouration of bracts and the onset of decay by a few days at temperatures around 5°C. Atmospheres below 2% O₂ may result in internal blackening of artichokes.

However, in most cases, low temperature and high humidity (>95%) will ensure better quality than use of CA/MA.

Storage disorders

Bacterial rots, Blackening, Downy mildew, Chilling injury, Grey mould rot, Powdery mildew.