Depending on the species, fish have varying amounts of proteins and vitamins, primarily A, B (B₁, B₂, B₃, and B₁₂), D, and E. They also contain minerals such as sodium, iron, potassium, and calcium. Regarding their fatty compounds, many species, especially oily fish, provide polyunsaturated omega-3 fatty acids. Specifically, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), are related to reducing the risk factors of cardiovascular diseases. Hence, fish is a fundamental part of a balanced and healthy diet. However, to maintain its nutritional properties, it is necessary to preserve it through proper cold chain management from capture, processing, and transportation to commercialization. This is the purpose of industrial refrigeration in the fishing industry.
Importance of industrial refrigeration in the fishing industry
As we said, most marine and freshwater species have highly nutritious value. However, they are perishable products that are susceptible to environmental conditions from the moment of fishing. Therefore, it is essential to refrigerate them immediately after their capture in the fishing vessels. Timely activation of this process helps prevent microorganisms present in these animals from starting the decomposition process. First of all, it is essential to determine the necessary resources and appropriate conservation conditions for each seafood product. With this, it is possible to ensure the maintenance of its nutritional and organoleptic properties, such as its odor and visual appearance.
It is worth noting that both the species and the fishing method determine the valid time for fish to be in perfect condition. One of the basic objectives of industrial refrigeration in the fishing industry is to ensure that seafood products are kept at the appropriate temperature from capture to the moment of purchase by the end consumer.
Likewise, the size and fatty content of each marine species also influence their valid marketing time. For example, small fish that contain a lot of fat, such as anchovies and sardines, usually remain in good condition for three to six days. In contrast, cod and hake can remain in good condition for three to four weeks. On the other hand, larger species such as swordfish can last up to 24 days without spoiling.
In this sense, it is critical to have broad and accurate knowledge of the composition of each product to establish the most convenient temperature for its preservation. Even those with high-fat content will require pre-freezing treatment.
Stages of industrial refrigeration in the fishing industry
We have already said that the cold chain to preserve the properties of marine and freshwater fish begins from the moment of capture and extends until the sale to the consumer. Below, we will summarize the conditions that should be considered in the design of industrial refrigeration in the fishing industry at each stage.
On-board refrigeration
Immediately after the catch, the specimens are refrigerated on board the fishing vessels. This process can be carried out in three ways:
- Pre-cooling. The catch is subjected to temperatures below 4°C. The resources for pre-cooling and cold maintenance are usually tanks of chilled seawater and/or flake ice. Typically, on some vessels, seawater at temperatures between 0°C and -1°C is used.
- Freezing. On the other hand, many fishing vessels carry out pre-processing of the fish once caught. This task can be carried out in plate freezers. Then, the pieces are subjected to rapid freezing at low temperatures for preservation during transport to land. These temperatures could reach between -30°C and -50°C.
- On-board conservation. In order to preserve the organoleptic conditions of the catch during transport to land, the load is placed directly in refrigerators with temperatures of -30°C. Depending on the species, this cooling could go down to -60°C.
By the way, these vessels always operate at sea and are exposed to movement and salt spray. Consequently, the design and development of cooling systems for fish on these ships is a challenge for industrial refrigeration in the fishing industry.
Processing on land, is another challenge for industrial refrigeration in the fishing industry
Subsequently, the processing plants on land receive the catch from the vessels. There, the cold chain must continue during preparation to be dispatched to sales points. Regarding this, the different environments should have the following ideal conditions:
- Fresh room. This will have a temperature between -1 and 0°C, close to the melting point of ice, as well as high humidity.
- Ice factory and silo. It is advisable to locate them in a chamber capable of maintaining a temperature close to 0°C. In the case of producing flake ice, the thickness should not exceed 3 millimeters.
- Workrooms. In these environments, the temperature can be somewhat higher at 12°C. However, it is critical that the airflow generated by the evaporators has a low airspeed on the workstations. The advisable speed is around 0.2 m/s.
- Storage chambers. Here, the frozen product must be in a closed container that does not allow oxidation or dehydration. In these chambers, the temperature will not be higher than -18°C. But, if it requires preservation for several months, it will drop to -30°C.
- Waste deposit. For these enclosures, the recommended temperature is -5°C. This generates superficial freezing that reduces the odor of the waste while awaiting evacuation.
- Fish and fresh seafood storage chambers. To prevent dehydration, it is necessary to cover the product with ice. In general, the temperature of these chambers will be between -1 and 1°C.
- Freezing tunnels. There are three types: continuous, semi-continuous, and static. Usually, their process temperature is between -35°C and -30°C. Continuous tunnels provide freezing times between 120 and 240 minutes.
Transport to Points of Sale
Once processed, frozen and packaged products must be transported in refrigerated trucks, containers, or ships to points of sale. In this regard, the aforementioned vehicles must have loading containers or tanks that guarantee a constant temperature of -20ºC or even lower. For their part, products intended for the domestic or local market, with an expectation of short-term consumption, only require the maintenance of the temperature for frozen products during transportation. That is, between -18 and -20ºC.
We can take on any industrial refrigeration project in the fishing industry
At Intersam, we design and develop refrigeration and air conditioning systems for any sector of industry and commerce. This has been our business since 1995. And we know it well! Our equipment and solutions have cutting-edge technology to guarantee maximum capacity and energy efficiency.
We can handle your industrial refrigeration project in the fishing industry anywhere in Spain and the world, where you are located. Whether you require refrigeration systems for vessels, trucks, processing centers, or points of sale. Contact us!