Limes

Infobox on Limes
Example of Limes
Freshness facts
Optimum carrying temperature	9°C to 10°C
Highest freezing point	-1,6°C
Acceptable product temp. at loading into containers	Max. 2°C above carrying temperature
Optimum humidity	90%
Ventilation setting for containers	25 m³/hr
Storage life	1-2 months
Climacteric / non-climacteric	Non-climacteric
Ethylene production	Very Low
Ethylene sensitivity	Moderate
Modified / controlled atmosphere	0%-10% CO2; 5%-10% O2
Potential benefits	CA storage can retard senescence, but commercial use is very limited
Availability
South America (Brazil) South Africa	January - June On demand

Limes

Harvesting and handling

Limes are very similar to lemons in shape and appearance, but they generally have no apical nipple. The flavedo layer is initially dark green, but it changes in colour through green to yellow as it ripens. If the lime is fully ripe, its peel becomes glossy. The greenish, generally seedless flesh is then very juicy and has a sour taste. Since the lime is more sensitive to cold than the other citrus fruits and its peel is thinner than that of the lemon, it is more problematic to transport.

The change in the colour of the peel is not a reliable measure of the ripeness of the fruit - it is peel gloss which indicates whether a fruit is ripe or not. Glossy limes are ripe, even if they are still green or have green spots. Another measure of ripeness is the Brix value, which determines the sugar/acid ratio of the juice.

Unlike many other citrus fruits, the peel of the lime is not chemically treated. The reason for this is that the peel is often used together with the pulp, and treated peel is toxic and flavour-impairing and therefore not suitable for eating.

High quality limes should be oval, firm, with smooth peel and deep green (Persian) or green and/or yellow (Key lime) colour. Limes should be turgid, and free from decay, splitting and blemishes.

Since limes are highly sensitive to impact due to their relatively thin skins, they must be handled with appropriate care.

In damp weather (rain, snow), the cargo must be protected from moisture, as there is otherwise a risk of premature spoilage.

Cooling and storage

Trade literature generally recommends storage temperatures of approx. +8°/10°C, at which lime fruit stores satisfactorily for approx. 6 to 8 weeks.

However, some loss of green colour becomes apparent after approx. 4 weeks of storage. After 8 weeks of storage, the rind colour is often yellow-green.

Green colour is retained better at approx. +4°C, but limes are subject to chilling injury at temperatures of approx. +7°C and below.

To ensure maximum transport and storage life, the fruit should be cooled immediately postharvest, as limes, like other citrus fruit, are susceptible to mould.

Limes 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.

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.

Seawater, rain and condensation water promote green and blue mould growth.

Mixed loads

Limes should not be mixed with ethylene-producing commodities. Lemons absorb odours from strongly scented vegetables and so should not be mixed with such commodities.

Cautions

O₂ below 5% can cause scald-like injury and decreased juice content. CO₂ greater than 10% may cause increased susceptibility to decay.

Storage disorders

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