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White cabbage, Brassica oleracea convar. capitata var. alba / Cruciferae (Brassicaceae)
Postharvest Atmosphere Management
Cabbages are not always subject to the pre-cooling process, although it is recommended in case of harvesting at high temperatures. It is carried out at temperatures of 1 to 5ºC. In general, the most suitable method is that of humid air, although cold storage rooms are also used.

Cabbages are not stored in countries where there are good weather conditions, since they have fresh cabbages all the year round. However, it is a common process in countries with more rigorous climate. In Spain, cabbages are frequently loaded in the field for their consignment to the market or industry.

The pieces are kept in bulk or in containers such as cages or pallets. The optimal conditions of storage are at temperatures of 0ºC and high relative humidity of more than 95%.

The early varieties can be maintained for more or less one month, whereas the late varieties may be kept for up to 7 months. The ethylene concentration must be maintained as low as possible, since it causes the yellowness and the falling of leaves.

Some trials have been carried out on the use of modified atmosphere for cabbages, but it is not used at commercial level. The optimal conditions are levels of 1 to 5% of oxygen and 2 to 6% of carbon dioxide. The use of these atmospheres extends the period of conservation. Cabbages keep their colour for longer time, and there occur less rots.
Distribution
Cabbages are transported at temperatures up to 15ºC, although distribution must not exceed 10ºC. The moisture levels must always be high, and ventilation must be such as to avoid the accumulation of ethylene.

The transport of cabbages must be carried out at temperatures between 0 and 5ºC, with pre-cooled hearts, although they admit temperatures up to 15ºC, according to the length of the transport. They must not be transported together with species that produce ethylene, so as to avoid damages.

The temperature of distribution must be of 5 to 10ºC. There must be good levels of relative humidity and a suitable ventilation. In order to improve the presentation, the yellowish leaves can be removed.
Postharvest Problems
Cabbages may show several diseases and physiological alterations during their storage. The diseases are caused by fungi or bacteria, like the gray rot or the black rot. Among the physiological alterations we find the black spotting, the marking of the nerves, the blackening of the middle nerves and the necrotic spots.

Gray rot: it is caused by the fungus Botrytis cinerea. It is one of the main postharvest diseases in cabbages. When the rot occurs there appears gray hair on the rotting.

Alternaria is a fungus that gives birth to dark brown or black spots with a not very dense, black coloured down.

Mycosphaerella brassicicola: this fungus produces injuries on the leaves, of dark brown-grayish or black colour. There are some black small points on them.

Sclerotinia sclerotiorum causes a soft and wet rot with small cotton white hairs.

Black rot: caused by the bacterium Xanthomonas campestris, characterized by a black down placed on the rotten area.

There are two bacteria that cause wet rots: Erwinia carotovora and Pseudomonas marginalis.

Among the physiological alterations we find the following:

Black spotting: characterized by small spots of this colour on the internal and external leaves. The reason why this occurs is still not clear, although it is thought that it may be influenced by the nitrogen fertilization.

Marking of the nerves: it takes place during long storage. There appear black or brown signs on the petiole and the central nerves. The causes are still unclear, although it is also thought that it may be influenced by fertilization.

Blackening of the middle nerves: it is characterized by the blackening of the tissues of the leaves petioles.

Necrotic spots: their causes are also unknown, and it is characterized by depressed injuries 1mm of diameter and multiple shapes. There is a high number of spots that end up joining, giving rise to larger affected areas.
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