What is the process for Canned Sardines? These are the essential Machines

The processing of canned sardines involves a series of crucial stages to ensure the quality of the final product. This article explores in detail the process and machinery used at each stage, from the reception of the sardines to their final packaging, highlighting the unique treatment of this fish.

Reception and Classification of Sardines

Size Classification

When the sardines arrive at the plant, they must be classified according to size. This step is essential as proper classification optimizes the efficiency of subsequent stages such as cutting, evisceration, and packing. Given the large volume of sardines to be handled, manual classification is not practical for this species. Typically, automatic systems are used, with each equipment model tailored to the capacity of each factory.

In this process sardine sorting machines are employed to grade the specimens into three, four, or even five different sizes. These grading machines, equipped with diverging rollers, facilitate selective storage of the fish and improve the overall efficiency of the sardine processing.

Freezing and Thawing

Sardines are a seasonal fish. Many companies freeze part of their catch during months of abundance and thaw it during periods of scarcity to maintain consistent production throughout the year. When fishing is limited or in regions where local sardines are not available year-round, it is also common to receive frozen sardines from third parties at the canning plant.

Freezing is a critical process that must ensure the proper preservation of the product. There are two main methods:

• IQF Freezing (Individual Quick Freezing): Sardines are frozen individually, which allows for greater flexibility in subsequent handling and facilitates use in automated production lines. The final product quality is superior because both the freezing and thawing processes are more product-friendly, as the freezing and thawing times are shorter, achieving more uniform quality in each piece.

  

  

• Block freezing: Several sardines are grouped into a compact block, which makes transportation and storage easier but requires a longer thawing process before processing. The final product quality may not be uniform depending on the thawing process used. This type of freezing is technically simpler and more cost-effective.

The thawing process is crucial to maintaining the quality of the final product. Thawing must be done carefully to avoid quality loss and is carried out in a thawing machine that preserves the fish’s properties intact. The thawing times must be appropriate for each size of fish, considering whether the fish were previously frozen using IQF or block freezing methods.

Sardine Preparation: De-scaling, cutting, and evisceration

De-scaling the sardine (if necessary)

Once classified, depending on the species and the fishing method, the sardine may require a de-scaling process. Some sardines arrive at the processing line with minimal scales due to their very light scaling, which is often lost during transportation or in the early stages of handling. Others, especially those from species with harder scales, need to go through a de-scaling machine.

This machine automates the sardine de-scaling process through a rotary drum equipped with a special mesh that facilitates the removal of scales. Additionally, the machine is capable of fully evacuating the scales thanks to a water filtering system.

Cutting and Evisceration: Performance optimization

After classification and the necessary de-scaling, the sardine undergoes a cutting and evisceration process, where the head, viscera, and tail are removed (although in some countries the tail is kept). This step is essential to prepare the sardine for packaging, ensuring that each piece is of uniform size to maximize its use.

In this process, the cutting and eviscerating machine plays a pivotal role, maximizing yield. Its adjustable versatility allows it to adapt to different fish sizes and the selective cutting of the head and/or tail.

Brining Process (optional)

Brining is an optional process that some producers use to enhance the flavor and texture of the sardine. During this process, the sardines are submerged in a saline solution, allowing them to absorb salt uniformly. This way, a specific salt concentration is achieved in the product, especially if the natural salinity of the fish from the sea is insufficient. Additionally, the aim is for the sardine to gain consistency and firmness to better withstand subsequent processes.

In the salmuerador, the sardines are submerged in a brine tank via a conveyor. This conveyor ensures that the sardines remain submerged for a controlled period, depending on the size of the fish and the desired salt level. At Gaictech, we recommend performing this process after cutting for greater effectiveness, ensuring that the salt properly penetrates the meat.

Packing

Sardine packing can be performed manually or automatically. Manual packing offers a more attractive and uniform presentation, especially in rectangular cans with formats such as ¼ Club and Dingley, where the appearance of the product when opening the can is very important. Automatic options are more efficient and recommended for large volume productions and are primarily designed for round formats. Naturally, manual packing is always a good option for small volume productions in any type of format, or where flexibility is required (various types of packaging, different types of sardines, etc.).

Sardine packing lines can be adapted to the different packaging formats to be used and the required production. Ergonomics, flexibility, and total control of the production process are key in packing. Therefore, Gaictech machines offer great versatility, being able to adapt to different production processes based on the type of packaging being worked with, speeds, type of presentation, etc.

Sardine Cooking

Continuous cookers: Functionality and design

Next, the sardine is cooked in continuous cookers, where the containers are placed in plastic grids to ensure the containers enter the cooker in an orderly manner. Once placed in the grids, the cans are introduced upside down into the cooker and follow a zig-zag path while being steamed. This method ensures that the fats released during cooking do not remain inside the can, thus preserving a smoother and more pleasant flavor.

The oils and fats collected during cooking can be reused thanks to the cooker’s design. These liquids are valuable by-products that can be used in the food or cosmetics industry.

This cooking method is the most common in countries with a strong tradition of canning along the Mediterranean Sea coast and is applied to various types of containers, depending on the country.

At this point, it’s also worth highlighting the cleaning process for the racks where the sardines are cooked. These racks go through a specific machine that consists of a double tunnel: a first immersion tunnel where the racks are submerged in a solution such as caustic soda (or an equivalent product, where caustic soda is not permitted) to soften the fats, followed by a washing tunnel with high-pressure water to thoroughly remove the fats and provide a final rinse. This grill washer effectively cleans stubborn fats and is specifically designed to wash all types of boxes previously subjected to cooking processes, where difficult-to-remove residues remain embedded.

However, there are other cooking options where the cans are not cooked upside down and the cooking liquids remain in the container during the process. These liquids need to be drained after the cooking process and before the oil or sauce is added.

There are other models of continuous cookers that adapt to these other cooking options and can integrate various automatic systems that connect packaging to cooking, for different container formats such as the more common oval and round formats used in other countries in America, Africa, or Asia. Additionally, automatic systems can be integrated to connect the output of the continuous cooker to the oil or sauce dosing line. This accelerates the process and requires less staff on the plant floor.

Oil or sauce dispenser

After cooking, the sardine passes through an oil or sauce dispenser, where it receives the desired amount of liquid to cover the entire volume of the container. This machine, integrated into the line, can allow successive dosages in containers of different capacities, ensuring that the product meets the proper liquid absorption parameters.

Washing, Loading into sterilization carts, and Sterilization

After closing, the cans are washed to remove any surface residues of oil or sauce and then loaded into sterilization carts before being sent to the autoclave for sterilization. This step is essential to ensure the cleanliness of the container and prepare it for the next stage. After passing through a cans washer, the containers are neatly placed into the sterilization carts (loading).

Sterilization in Autoclaves

Sterilization is a critical process that ensures food safety and long-term preservation of canned sardines. This process uses high temperatures and pressure to eliminate any microorganisms, guaranteeing a safe and high-quality product.

The sealed cans are placed into carts (loading), or stackable cage-like structures if dealing with flexible containers like pouches. These carts are then introduced into the autoclave, a large pressure vessel designed to withstand high temperatures and pressures.

The autoclave is filled with either steam or superheated water, depending on the chosen operating system. The internal temperature is then gradually increased until it reaches between 115°C and 121°C (239°F-250°F), according to the type of container being sterilized or the client’s sterilization preferences.

Drying, Labeling, and Cartoning (if applicable)

After sterilization, the cans are cooled with water, unloaded from the carts (removed from the carts in an orderly manner), and dried to remove any residual moisture before labeling or cartoning.

At Gaictech, we manufacture efficient can dryers that use hot air and steam to ensure the cans are completely dry. These machines incorporate heat exchangers and air-knives to leave the can surfaces water-free, allowing for subsequent processes (labeling, cartoning, and in some cases, inkjet printing of specific information such as production date, expiration date, batch, etc.) to be carried out reliably.

Depending on the market, type of container, and final presentation, the cans can be packed into cardboard boxes or directly labeled. In the case of lithographed cans or cans with artwork printed directly on them, this process would not be necessary since all product and client information is printed on the can itself.

Finally, the cans are grouped according to the client’s preferences (cardboard boxes with ‘x’ units, groups of ‘x’ shrink-wrapped cans with shrink plastic, etc.) and the final product is palletized for distribution and sale. In this aspect, we offer automatic palletizing solutions that can adapt to all types of formats and container sizes. Thanks to their high degree of automation and connectivity, they allow for precise and real-time control of their operation.

Feeding empty containers to the packing lines

Feeding empty containers to the packing lines is a parallel and complementary process to the main production line. Manual or automatic packing lines need to be supplied with the empty containers where the product will be introduced.

There is a wide range of possibilities here, depending on the type of container being used and the desired production, from very simple semi-automatic solutions to complex robotic systems that can supply multiple production lines at high speed.

Conclusion

The production process of canned sardines is complex and requires specialized machinery to ensure a high-quality final product. From receiving the fish to its packaging and final palletizing, each stage is crucial to maintaining the standards characteristic of the canned fish industry.

That’s why at Gaictech, we are committed to providing efficient, rigorous machinery tailored to your company’s needs. If you need more information or specialized advice, don’t hesitate to contact us.