Cooling sweet potato with Dutch technologyCooling sweet potato with Dutch technologyCooling sweet potato with Dutch technology

Cooling sweet potato with Dutch technology

Senior storage specialist Huub Maerman talks about his experience

In addition to potatoes, onions and carrots, TOLSMA also takes care of the storage of all kinds of 'special' products. For example, pumpkin, garlic, sweet potato and celeriac, the storage specialist has all the knowledge and materials in-house. "We never really say no."

"The beans for Jumbo that come from Zambia out of season? They are kept fresh there in a Tolsma refrigerator." Senior storage specialist Huub Maerman easily lists projects in the Netherlands and abroad where the company has set up storage facilities for products other than the potatoes, onions and carrots for which the storage specialist is best known in the Netherlands.

One of the newcomers is the sweet potato. "It is easier to store than to grow," Maerman says. "You can store the sweet potato at about 13 degrees, so you don't need refrigeration under Dutch conditions. It can simply be stored in a standard box storage. But because it is a vulnerable crop, wound healing does require a lot of attention. Also the ventilation and so CO₂ measurement is accurate. And to minimize moisture loss, the RH must remain around 90%; you really have to control that. For pumpkins, the RH must be a lot lower."

Condensation drying
Maerman has seen an increasing interest in condensation drying in the storage of these various tuberous plants in recent years. This is easily explained, according to the storage specialist. "For celeriac, for example, you first have to be able to cool quickly. There is sometimes a lot of life in a batch. The temperature can rise from half a degree to a whole degree within a day. But you also need drying capacity because you don't want the foliage starts to mold, then condensation drying is the ideal technique." According to Maerman, you cannot avoid condensation drying for the storage of garlic either. "You keep that at minus 3 and an RH of 70%. You can't do that with cooling alone."

First weeks essential
Years of experience have taught Maerman and his colleagues that the first weeks of all agricultural products are essential for the ultimate storage result.

Maerman: "A good start is half the battle, also with storage. You have to be on top of it in the beginning. Look carefully at how the product arrives and respond to it. For example, it sometimes happens that carrots are brought in in October under fairly warm conditions. Then it is crucial that the product is cooled quickly. Carrots, like the sweet potato by the way, have virtually no skin and then you lose too much moisture at high temperatures. But products that arrive relatively dry, such as pumpkins, require a lot of attention immediately. after storing it in. If you let it slip, you will just have problems with fungi or bacteria." In principle, Tolsma has the storage knowledge in house for all the aforementioned 'special' products. "And if we don't know something, we just dive in and test it," Maerman laughs. "At Tolsma, we are not so quick to say no to questions from our customer."

Direct contact with the customer
Even when it comes to technology, the storage specialist from Emmeloord is not always short of a solution. "We make everything ourselves at Tolsma, so we can switch quickly," explains Maerman. "And because we have direct contact with the customer, communication about a job always runs smoothly. There is no one in between and half a word is usually enough for us. You always have a fixed point of contact with us."

Maerman emphasizes that Tolsma is really not just about large new installations. "We regularly set up smaller cells for organic growers or people with house sales in which all kinds of products are stored. The trend of 'local for local' has given this a boost. And we also regularly adjust existing storage facilities. At the moment, arable farmers are opting for mechanical cooling in combination with the new generation of sprout inhibitors, which is often fine in an existing storage facility."