The optimal temperature for storage during 6 or 12 months is 0ºC, depending on the variety (semidry dates like "Deglet Noor" and Halawi, have a longer period of life than other fresh dates like "Medjool’ and " Bardhi’).
At -18ºC (0ºF) the period of storage extends. The freezing point is –15.7ºC (3.7ºF).
The optimal relative moisture oscillates around 70-75%.
Cooling is the technique used to preserve soft dates varieties for two weeks. In order to avoid dehydration, dry dates must be stored in cool and dry places, protected from the sun and air. Under these conditions the period of storage lasts for several months and even a year.
The fresh produce consumed at present are put under preservation processes immediately after the harvest, ultra-frozen and later on defrosted just before they are put into sale. Dates which have undergone this treatment are barely damaged because they contain very little fluid and a lot of sugar (up to 70% of the total is inverted sugar).
Ripe dates are hardly influenced by ethylene but they can really absorb the aroma of some other produce. Dates must not be stored next to garlic, onions and potatoes.
Storage under controlled atmosphere with nitrogen (excluding oxygen) diminishes rottings of the dates and prevents the infections caused by insects.
For further information consult the Web page of the University of Davis (
http://postharvest.ucdavis.edu )