When cooling our apples, we work with the principle of ULO storage. This means that, thanks to U.L.O. or Ultra Low Oxygen, Tilkens Fruit can keep apples and pears that have been harvested in the autumn for a whole year.

Quality is not compromised and it means that we can supply our customers with quality fruit throughout the year.

U.LO. or Ultra Low Oxygen.

This storage method involves maintaining an extremely low oxygen level and a raised CO2 level.

Storage takes place in gas-proof, sealed storage cells (see photo) and is used for long-term storage of apples and pears, among other things.

In this way, Jonagold can be stored until the end of July at 1°C, 4 % CO2 and 1 to 1.2% O2, while ordinary air is made up of about 78% nitrogen gas, 21% oxygen and 377 ppm CO2.


During storage, sugars contained in fruit are broken down into CO2 as a result of the presence of air. Consequently, oxygen is used and the level of CO2 rises.
If the CO2 level is too high, anaerobic respiration can take place during storage and this results in the appearance of brown colouring. Respiration is slowed down by a low oxygen level and the storage period is, therefore, extended.


<palign="left">A cool cell under ULO is extremely dangerous. This is due to the fact that breathing in CO2 leads to oxygen being removed from the blood and a lack of oxygen in the brain can lead to fainting. If you stay in the CO2-rich air for too long, there is a chance that you may suffocate or die as a result of a lack of oxygen in the brain.

People quite regularly die as a result of incompetence in this regard.

In order to prevent a cool cell under ULO being opened accidentally, extra locks must be fitted to the door. The doors must also be equipped with the appropriate stickers, warning of the low oxygen level.

After opening the door, the cell must be given sufficient time to allow the level of oxygen to rise.