Storage of Fruit

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(Ultra Low Oxygen) in Vittsjö (South Sweden)

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  Storage of Fruit
















Why store your harvest in a ULO-storage facility?

Fruit storage is an art that has been refined through the centuries. In this case, we can say that it was not 'better in the past', at least, not for fruit growers. With a ULO-storage, an apple harvest can be sold all year round – without affecting the quality of the fruit. In this way, the fruit grower can dramatically increase its profit. This is due to the fluctuating market prices during the year.

ULO-cells can be built in different sizes, but the minimum recommended size has a storage volume of 70-80 000 kg apples. Many fruit growers choose to build cells that contain a volume of 120.000 kg and 150.000 kg, which requires a surface area of 110 square meters.

It’s of course up to the customer to decide how many cells are built, but the rule of thumb is that the more cells a storage facility contains, the lower the storage costs are per kg apples. It is also possible to build a storage which has options for expansion with additional cells at a later stage.

Which fruits and vegetables are suitable for ULO-storage?

We at Saarloos are of the opinion that ULO type storage facilities are specifically suitable for apples and pears. Traditionally the ULO-storage technology was mainly used for storage of apples. It can however be successfully used for the storage of other varieties of fruits and vegetables.

It is important to know that different varieties of fruits and vegetables can’t always be stored together in the same ULO-cell. Apples and pears can’t be stored together in the same cell. On the other hand, it is possible to keep some different apple varieties together in the same cell. Saarloos has firsthand experience from running its own ULO-storage in Vittsjö, Sweden, and will be glad to help its customers with advice on this subject.

Fruits that are suitable for ULO-storage: apples, pears, kiwis, blue berries, mangos, cherries and pomegranates.

Vegetables that are suitable for ULO-storage: artichoke, asparagus, broccoli, sprouts, cabbage, cauliflower, celery/celeriac, onions, eggplant, garlic, fresh herbs, leek, lettuce, okra, beans, bell peppers, chili peppers and tomatoes.

Cherries are often stored in plastic bags, in which the air composition is controlled with a CA system (Palliflex). Up to 300 pallets can be separately controlled with a single control system; the air compostion per pallet can be managed, which offers great advantages for the storage of all types of soft fruit.

How does ULO work?

An ULO-storage facility consists of a number of important components.
ULO means Ultra Low Oxygen, which means that ultra low oxygen is combined with cooling and the adjustment of carbon dioxide and nitrite levels which makes long storage periods possible.

.The normal atmosphere contains ....An ULO-cell contains
.Nitrogen... ......... ..79%
.Oxygen.... ....... . 20,9%
.Carbon dioxide
....... .97%
.... ......1%
.... 0,7-4%

The oxygen in a normal atmosphere makes the apples ripen, and by both lowering both the temperature and the oxygen in a ULO-cell, and adding nitrogen, the fruits are ripening much slower. In a way you could say that the apples are sleeping. Important is to manage the level of carbon dioxide, as a too high level of carbon dioxide can destroy the fruit.

In order to get a good result, it is important that the ULO-system works without problems. As the percentage levels for the different gasses above show:  there are small margins that need to be monitored to be correct and in balance in order to ensure that the storage is working correctly.

The cooling system in a ULO-building is specially constructed in order to manage the humidity. Every time you cool down apples, they lose moisture, which a normal cooling system can’t control.

Often, the larger portion of a fruit grower’s annual production is stored in a ULO-storage, and for this reason it’s important to minimize the risks. When you consider the value of a harvest that is stored in a ULO-storage, it’s comparable with keeping your savings in the bank. In this case, the harvest is your savings.

This approach makes that Saarloos feels that it has a major responsibility towards the fruit grower and that’s why Saarloos chooses the best components available when constructing a ULO-storage facility. To compromise on quality is not an option when considering the risks.

Saarloos dealer/supplier for Scandinavia of van Amerongen products.

On our internal webpage "products" you can read how a ULO-storage facility is built, and which machinery is needed. We cooperate with the world-renown Dutch company Van Amerongen which produces several components that we use when constructing a ULO-storage. Van Amerongen has over 40 years of experience in development of these systems and is the company that invented the ULO technique. Van Amerongen is represented in over 50 countries all over the world, and in Scandinavia, Saarloos is the dealer and an exclusive supplier and installer of Van Amerongen products. This makes us very proud as it shows their trust in our expertise, experience and know-how.

Van Amerongen has produced a video in which in a clear manner it is explained how the ULO-system works.

Video Van Amerongen