KLM Catering Services (KCS) Schipol is the biggest in-flight caterer in the Netherlands, with over 250 flights a day, producing 35,000 daily meals and catering for 2,500 special diets. KLM not only caters for its own scheduled flights, but also supplies meals to many other airline operators such as Northwest Airlines, Cyprus and Kenyan Airways. 90% of the in-flight meal is brought in frozen, and placed in cold storage, prior to preparation in KLM Catering Services different locations, which are subdivided into their Foreign, European and Intercontinental assembly areas.

The meals can be stored for anything from 3 days upto 6 weeks, depending on whether they are for infrequent special dietary requests. The quick freezing process means rapid throughput and high product quality demand.Part of a recent integration of buildings has produced a streamlined equipment flow, which combines preparatory kitchens and cool freeze areas to increase KCS’s productivity. Preparing in-flight meals raises its own difficulties with ambient temperature often 20 to 30oC in Summer, and the food preparation areas requiring to be maintained at 14-15oC, before the products enter the adjacent cold storage freezers at –20oC.With freezing at these temperatures you get a lot of humidity, on account of the wide difference in temperature and pressure between the ambient air and that in the cold storage freezer. Moist air streams into the -20ºC store every time the doors are opened, due to the frequent deliveries throughout the day.

The result is frosting and icing up of the floors inside and outside the storage area, icing of refrigeration components, such as the evaporator, and also frosting of product making it difficult for the food technicians to read the product labels. By far the greatest concern of Edo Cuiper, KLM Catering Services Technical Engineer was the freezing snow and ice on the floor and ceiling “The floor was very slippery and unacceptably dangerous, we had to do something” he said. As well as the risk of accidents Edo said “We had ice and snow on the evaporator, it was difficult to clean, and difficult to keep at a constant -20oC”, we had frequent defrosts, typically six times daily for one hour”.

The simple and effective answer was to remove the moisture from the air and this is exactly what Munters IceDry® systems do so well. KLM Catering Services installed three IceDry® systems in their cold stores, as Munters system is purposed designed for low temperatures. Munters desiccant dehumidifiers work by drawing air from the cold store through a rotor containing silica gel. 

In removing moisture from the air, Munters calculate, then control the dewpoint temperature required - the point at which moisture in the air will condense out and freeze onto surfaces. Once the moisture in the air is removed, the now ultra-dry air is piped back into the cold store area. By removing the moisture, the IceDry® system also assists increase the periods between defrost, reducing energy utilisation and refrigeration plant cleaning.“The difference before and after the installation of IceDry® is like night and day” says Edo Cuiper, “The coldstore rooms are clean and the floors are no longer slippery” The safety improvements also got the thumbs up from the “ARBO” welfare at work organisation. Improving the safe operation of the environment had previously been attempted by adding grip strips into the floor to make it less slippery. This proved unsuccessful as after only two weeks, the ice built up again. Now with IceDry® this is completely clear. Moving the food pallets is also much safer, and loading is faster, the catering team can read all the labels correctly, without having to wipe the frost off labels away.The improvements have not only been seen in safety, KLM Catering Services now only defrost once a day for half an hour, it is not really necessary however is done as a precautionary measure for cooling equipment safety.

Previously KCS observed ice build up on the coldstore fan during the night, which occasionally was so severe that it meant that the fan could not blow anymore. Now this has been completely solved with Munters IceDry®KCS have also found through their constant electronic temperature tracking, that they have been able to maintain much tighter temperature control. The reduced defrost with IceDry® has also enabled KLM Catering Services to reduce the temperature of the refrigerant evaporator coolant from –27oC to – 22oC KLM Catering Services see the installation of  Munters IceDry as a primary element of their HACCP initiative for safe and effective working, in short, it has been a great success.


In freezer production, icing is often the cause of interruptions , food releases moisture and becomes water vapour, which coupled with the moisture in the air and cleaning process can make equipment and freezer compartments ice up rapidly.  The consequence is frequent productions stoppages to defrost and clean. With Munters IceDry®  system moisture is removed and for Unilever’s Langanese Iglo this meant freezer running time was almost doubled by dramatically reducing the periods between defrosts.

Productivity improvement and quality are a constant concern, especially in freezer production, where avoiding stoppages due to defrosts and uneccessary cleaning due to ice means significant productivity gains. At the Technology-Centre of Langnese-Iglo part of the Unilever Group, they scale up manufacturing improvements to factory production and adapt existing production methods to the new conditions.

The production of bread and pastry snacks (frozen Bistro-baguettes) is an around the clock operation, so reducing stoppages and extending production times was the only option. The cause of disruption was icing up of the freezer.  The baguettes are packed after being frozen, to avoid sticking together of the topping with the packaging. However fresh ingredients of toppngs release a lot of moisture into the freezer.  Also the difference in pressure between the air in the freezer and the surrounding air causes moist outside air to be drawn into the freezer. All this causes condensation and icing up of the evaporators, which in turn reduces the cooling effect and the conveyor belt has to run slower so that the products can be frozen sufficiently.

.After four shifts, production stopped in order to defrost and clean the freezer.  “Each defrost procedure meant up to six hours production interruption and employing two staff, who have to defrost the freezer with a lot of warm water,” explained the Head of the Technology Centre. To reduce these stoppage times and install a new freezer was too high an investment.  “The freezer is the central part of the production line with a life span of 10 – 20 years”, said the  Head of the Technology Centre.  The aim was to extract moisture from the air before it condenses on the evaporator and slowly ices up, at the product entry into the freezer.

By using Munters IceDry®” system the freezing  up of the evaporator was clearly reduced. Previously the past freezer had to be defrosted and cleaned after 3-4 shifts, but now has been extended to 6-7 shifts.  That means not only an almost a doubling up of the running time, but also a constant running speed is kept for longer. 

Langnese-Iglo produces over 100.000 tons of products yearly for Unilever in Europe.  Bread, cake and pastry snacks (Bistro baguette), mixed vegetables, well known stir-fry vegetables, ready-to-serve meals and the popular spinach originate from the freezers of this production location .  At Langnese-Iglo they also produce high quality frozen ready-meals.  Here the frozen ingredients have to be mixed exactly to the recipe in the freezer installation.  That is dealt with by electronic scales, which always empty their small bowls, when the right amount of frozen vegetables are weighed.  Since this production step is carried out under freezing temperatures, the scales often malfunction because of the increased ice build up.

Every time during cleaning, moisture entered the air in the room, which after only a short time formed frost and ice.  Then the fine mechanism of the bowls jammed and production had to stop”, explained the Head of the Technology Centre. “In addition the floor was icing up badly and the accident risk for staff increased.  Besides regular production stoppages, the safety risk was not acceptable for us”.

A Munters IceDry®  system was installed above the production room to dry the room immediately after cleaning, so when cooling to minus temperatures no frost and ice forms  because the air has low moisture.  In the production plant disruption through new frost forming has been significantly reduced with the help of dry air being blown in and the safety risk for employee slips has dropped considerably. Munter IceDry®  system takes care that the highly precise scales at Langnese-Iglo now work in ideal atmosphere, providing a trouble free operation. With 28 offices worldwide why not contact your local office at  www.munters.com/food, or telephone ++44 (0) 1480 4423 or  Email food@munters.co.uk
Νέα 12/2008

Munters Humidity control Unit for industrial facilities (HCU) provides operators the ability to control temperature and humidity independently !
For more information please visit www.munters.com

Νέα 12/2008

Participation in the 20th International Exhibition for Food, Beverages, Machinery and Equipment, DETROP '09, from 6-9/03/2009, pavilion 2 stand 16.