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Spinach, Spinacia oleracea / Chenopodiaceae
Postharvest Atmosphere Management
It is recommended to market spinach immediately, although they can be stored at temperatures of 0ºC and moisture over 95% for a period of two weeks, which are extended to four weeks if the produce is of good quality and the environmental conditions are strict.

Spinach benefit from fast pre-cooling, that diminishes its metabolic activity and increases preservation. The temperature must be preferably of 0ºC. With pre-cooling and packaging in plastic bags the storage may last up to 40 days.

Cool storage around 0-(-1ºC) and 90-95% of relative moisture enables the produce to last between 2 and 4 weeks. It is extremely important to maintain high levels of relative moisture during the storage of loose leaves, that is to say, unwrapped produce. When plastic protections are used, the environment inside the plastic bag has a high level of relative moisture

Controlled atmospheres adding 10-20% of carbon dioxide have only a slight effect in preservation and they are not used at commercial level. It has been proved that the addition of 10% of carbon dioxide prevents yellowness and increases in one week the storage of spinach, with a temperature of conservation around 5ºC. Plastic films have been chosen to package pre-washed spinach leaves kept at 1-3% of oxygen and 8-10% of carbon dioxide.
Distribution
Transport must be carried out at low temperatures, between 0 and 5ºC, and high environmental moisture. The maximum temperature recommended when loading is 6ºC, for no longer than 3 days.

During distribution the levels of moisture must be high, in order to avoid drying, and the temperature must not exceed 10ºC.
Postharvest Problems
The metabolic activity of spinach is one of the highest among the leafy vegetables. It is a determining factor of its brief post-harvest life, that hardly surpasses 12 days.

After the harvesting arise a series of changes that may deteriorate the quality. The most frequent are: dehydration, yellowness, changes taste, compositional changes and diseases caused by blight and loss.

Dehydration
The loss of water causes the blight of the produce and therefore, the loss of the fresh appearance. Plastic protections reduce this problem.

Yellowness
The degradation of chlorophyll is a process associated to senescence having as a consequence the yellowing of the leaves, an undesired phenomenon occurring in leafy vegetables.

The lesser amount of losses of chlorophyll take place at 10ºC, and there are not many differences between wrapped and unwrapped spinach. At 20ºC the treatments with plastic are those that maintain the best colour.

Compositional changes
During the post-harvest there is a series of compositional changes among which are the diminution of ascorbic acid (vitamin C), proteins and the increase of thiamin (vitamin B1)

Low temperatures slow down these modifications. It seems that the loss of water acts as an accelerator of vitamin degradation.

Diseases

- Humid rot: It is caused by the bacterium Erwinia carotovora, being the main disease of harvested spinach. The tissues affected have a watery appearance and a dirty green colour. There is a softening of the leaves and an unpleasant smell. Low humid air stops the disease, and the tissues dry and become fragile.

- Powdery mildew: It manifests during production. It is caused by the fungus Peronospora spinaciae. In spinach coming from affected fields the fungus may develop during transport and the marketing stage. The leaves show some areas with a whitish powder.

- Grey rot. The fungus causing this disease is Botrytis and it affects many other species.
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