It is advisable to store almonds at temperatures between 0 and 10ºC and low relative moisture. Conservation is also improved by controlling the levels of oxygen and carbon dioxide.

The shell varieties that predominate in Spain can be stored for longer time than those with soft shell, without rancidness danger. The optimal temperature is at 0 to 10ºC; the lower it is, the better the almonds will be stored . The optimal relative humidity in storage will depend on the moisture of the produce. The almond is a dry fruit with low water content, so moisture must be avoided. Moreover, by controlling the levels of the ambient components we can also influence the conservation of the produce. Therefore, under controlled atmosphere with oxygen concentrations below 1%, rancidness and other symptoms of deterioration are delayed. Oxygen concentrations below 0.5%, balanced with nitrogen, and/or carbon dioxide levels over 80% in the air can be effective to control the insects that attack stored produce, being an alternative to chemical fumigation.

For more information and recommendations to maintain the postharvest quality of almonds and other dry fruit, consult the Web page of the University of Davis ( http://postharvest.ucdavis.edu )

Physiological alterations of the product or diseases caused by fungi may appear, since they attack mainly in conditions of high moisture.

There is a series of physiological alterations like physical damage, that is to say, the shell breaks and for that reason the storage life shortens; and the damage by ammonium, to which they are very sensitive, causing the blackening of the external tissue.

In addition, several insects can damage the stored fruits. In order to diminish the attacks of insects there must be a good hygiene. Fumigation may be carried out with approved chemical products, although every time less, in order to avoid problems with residues. Other methods to control them are by means of irradiation, heat treatment and controlled atmosphere. These fruits are also very attractive for squirrels and some birds.

The diseases that affect the fruits are produced mainly by fungi.

1 Aspergillus flavus
The fruit infection may begin before the harvest and its development is favoured by rainy and damp weather, or whenever the almonds are damaged by insects. The best way to avoid the fungi development in already harvested products is to maintain them in optimal conditions of temperature and relative moisture during the postharvest handling.

2 Cladosporium carpophilum
It affects the almond tree and the peach tree and in some cases the apricot tree, in plantations where the moisture levels are high. If it attacks early, it brings about the fruit drop, injuries with dark spots that may produce cracks and deformations. If the attacks take place in the cold storage rooms, the spots are sporadic, silky black and they do not cause deformations.