Maybe you already knew it. Apples, among other fruits, can lie in a cold storage room for more than a year and still be sold fresh. It sounds impossible, but it really is true. By creating the right conditions in a storage unit, we can preserve freshness! But we need to be careful with these storage rooms because they are very dangerous.
What is the best environment and climate?
The conditions needed to preserve fruit for so long can be achieved in special cooling units. These cooling units are called ULO-Cells. This stands for Ultra Low Oxygen cells. In these gas-tight cells, the amount of oxygen is reduced and the amount of CO2 increased. Depending on the type of fruit that needs to be stored, the conditions in the ULO cell can vary.
- Temperatures often vary from -2 to 5 degrees Celsius.
- The oxygen content is reduced to 1.2% (in normal air this is 21%).
- The CO2 value is increased to a maximum of 4%.
- The humidity is kept high to prevent dehydration/moisture loss.
When the values for the product have been determined, it is a matter of controlling these conditions. This is controlled by special computers. During the week they measure the air in the cells to check the values. Whenever an adjustment is needed, the computers will take care of it.
The entire respiration process of the fruit is slowed down by this. The fruit is in 'sleep' as you can say.
To preserve the fruit even longer it can also be put into a 'coma'. DCA cells exist for this purpose. This stands for Dynamic controlled atmospheric cells. Instead of a some measurements per week, the values are adjusted continuously. The oxygen content can drop below 1%! Alcohol values are also measured in order to be able to adjust any fermentation.
The ULO and DCA cells are very dangerous
You can now guess why these cells are incredibly dangerous to us. People literally do not last a second in these cells. With one good gulp of air you will already become unconscious. Without feeling nauseous or dizzy. After you become unconscious, the next thing is no surprise because you will suffocate due to the lack of oxygen. To prevent this, there are strict protocols for working with these cells. For example, you may only go near these cells if there are at least two of you and you have oxygen meters with you.
ULO cells offer benefits for everyone
Despite the fact that the cells must be handled with care, there are actually benefits for everyone. For the growers, it is a great way to store their product for a longer period of time without spoiling it. Because there is less 'rush', they can ensure a better quality apple. This way they can provide us with fruits all year round! So the consumer has fresh products all year round!
(Veilig werken in en rond ULO-Cellen, 2020)
(Ultra low oxygen-cellen (ULO) voor o.a. opslag van fruit, n.d.)