In general, refrigeration and cooling systems in the agri-food sector are critical. In fact, the cold chain to maintain the conditions of the product, slow down the development of bacteria and prevent its deterioration, begins in the processing companies. To achieve this, the use of equipment such as cooling and freezing tunnels is essential. In general, refrigeration plays an important role in this industrial segment, which is one of the largest in the Spanish economy.

Read on to learn a little more about these machines and their importance in preserving many of the foods we eat.


What are cooling tunnels and how do they work?

Cooling tunnels are systems used in various food processing facilities for fruits, vegetables, snack foods, baked goods and more. In essence, these machines provide controlled temperature reduction, whether in batch or continuous process systems. Structurally, they bear some resemblance to convection air ovens, although they do not provide heating.

In this sense, the cooling tunnels use blowers that introduce ambient air or outside air into the tunnel and extract the hot air from the products at the opposite end. Consequently, the passage of air over the pieces allows for more uniform cooling in much less time.


Types of cooling tunnels and some characteristics

Basically, there are two kinds of cooling tunnels: continuous and discontinuous. The first ones are designed for those applications in which all the products need the same cooling time.

Unlike discontinuous cooling units, created for processes in which the products must leave the tunnel once the required final temperature has been reached. These are usually more expensive than continuous but are more efficient in terms of energy consumption. They can also manage product pallets of different heights and reduce their handling time during cooling. In general, these cooling units may require accessories such as:

  • Elevating, vibrating or removable tables.
  • Additional space for the arrangement of products.
  • Granular feed distribution systems.
  • Integration with other processing equipment.

Depending on the types and characteristics of the processes, some cooling tunnels may be portable or modular in design. In addition, there are others that have a programmable logic controller (PLC) and a digital control panel. Its red and green light-emitting diodes (LEDs) warn if the refrigeration equipment is on or off, or if indicators such as temperature need to be adjusted.


Which cooling tunnel to choose?

Of course, choosing between existing cooling tunnel types requires an analysis of product and process specifications. This will determine its most common features and elements, which would include:

  • Tunnel length.
  • Conveyor width.
  • Conveyor belt material (metal or plastic; rough or smooth surface depending on the application).
  • Shell material,
  • Humidity range.
  • The number of cooling zones.

On the other hand, many industrial applications of the units at hand require conveyor belts made of stronger and more durable materials. Generally, stainless steel is the most selected material for both the tunnel cover and its side panels. The number of cooling zones is variable according to the model and the manufacturer. At the layout level, we can classify top-cooled and bottom-cooled products.


Cooling or freezing tunnels? Which ones do you need?

As obvious as it may seem, answering this question allows us to establish the differences between cooling and freezing tunnels. Indeed, a tunnel freezer is a type of industrial machinery capable of quickly freezing any food. Whether it is fruit, vegetables, meat or fish, these products may require freezing of these characteristics for their transport and conservation.

Quick freezing affects these foods less, as it prevents the creation of large ice crystals that break their tissues. Through this procedure, these products are last longer frozen. And, by reversing this process, they distill less water. There are various designs to adapt these units to the needs of the food industry and for their preparation materials are used that do not modify the organoleptic conditions of such foods.

In fact, there are different kinds of freezing tunnels that respond to particular situations. One of them is cascade freezing, which is very similar in appearance to a cold room, but whose operation is different. Inside it, air at sub-zero temperatures is poured; it falls from above, simulating a waterfall, and quickly freezes food. Then, all the products reach homogeneous freezing with minimal dehydration, so the process guarantees high-quality products.


Advantages of freezing tunnels

These units quickly freeze large quantities of food, which means a considerable increase in efficiency in the production chain. Apart from that, its management is simple and usually requires the participation of one or very few operators. This reduces personnel costs. Furthermore, they are flexible and scalable machines. In other words, they are adaptable to different circumstances and expandable over time. In this way, when production processes evolve, it is feasible to reconfigure them almost without any difficulty.


Importance of cooling tunnels in the food industry

A recent study forecasts that the Spanish frozen food market will grow at a compound annual rate of 2.1% between 2021 and 2026. This assessment is based on changes in consumption patterns and preferences toward ready-to-eat and convenient foods.

In this regard, they identify as frozen foods those that are preserved by means of a freezing process and that are kept in that state until they are consumed. These products are meat, poultry, fish, shellfish, fruits, vegetables, desserts, prepared meals, bakery products and snacks, among others. In particular, frozen foods facilitate the preparation of recipes, since the time and effort invested is less when compared to cooking from scratch. For this reason, they are the main ingredients of the dishes that are prepared and served in homes and restaurants.

As we said, the factors driving the growth of the market for these products in Spain are changes in consumption patterns and purchasing habits. Likewise, the increase in the number of people who work and a sustained increase in the demand for ready-to-eat products have an influence. The latter stems from consumers’ increasingly hectic lifestyles. Therefore, it is not surprising that it is those under 35 who lead this trend to consume fast food or ready to eat.

To this, we add the availability of frozen foods that motivates many more consumers to buy them. In this line, manufacturers launch a wide variety of them on the market: meat, fish products, frozen potatoes, ready meals, etc. Equally, this favors the growth of the industry.


Keeping cold and quality, two key requirements

Taking into account the above, the companies that process the mentioned foods make an effort to start and maintain the cold chain of their products. Consequently, the cooling and freezing tunnels play a predominant role, since they start this process. The same will be kept in the warehouse and transported to the points of sale. All this will guarantee the buyer that he will consume a fresh and quality product.


Do you need a customized cooling tunnel?

At Intersam we have been developing various industrial refrigeration and air conditioning systems since 1995. Our experience allows us to supply high-quality products that guarantee the best treatment of airflows. If what you require are cooling tunnels for your food processing company, we build them with the most advanced technology. And we move them to wherever they are, inside or outside of Spain. Do you need advice? Contact us now!