Mussel Machinery: Discover their Canning Process

The production process of canned mussels is essential to ensure this bivalve, highly appreciated by consumers, reaches the markets in optimal conditions. The industry of canned mussels hinges on a series of well-defined processes, where mussel technology and machinery play a crucial role in ensuring product quality. In this article, we will explore the different stages of the process, from reception to final canning, highlighting the importance of machinery and its function at each phase.

We will analyze the process for the different presentations of the final mussel product: canned, frozen (meat or half shell), pasteurized, and fresh.

Reception of Mussels

How do mussels arrive? De-shelled and in clusters

Mussels reach the factories in various states, either shelled, meaning loose and free from clusters, or in clusters, where they are bound by sea residues, byssus, etc. This difference influences the initial steps of the process.

Depending on the country and the farming methodologies used, mussels can arrive at the factory in bulk trucks that unload into large hoppers at the beginning of the production line or in plastic bins, both systems suitable for their subsequent processing at the plant.

Cleaning and waste removal: initial preparation

This declumping is carried out using a special machine called a mussel declumper, which, in the case of Gaictech, consists of two parts:

• A declumping drum where the mussels are ‘declustered’ and separated one by one from the cluster.
• A classification and washing drum, in which the now loose mussels are washed with large quantities of water to remove remaining residues and impurities. In this phase, besides removing pieces of broken shells or impurities, smaller mussels measuring less than 14-15 millimeters are filtered out. The water used in the process can be either saltwater or freshwater, and in the latter case, it can be filtered and recirculated to reduce water consumption. Saltwater is usually disposed of into the sea if the factory is near the coast.

If there is no declumping, the process proceeds directly to cleaning.

Mussel Classification

Separation by size

Generally, mussels are classified into three sizes using divergent rollers. This classification of the mussel with shell enables optimal processing, as each size has specific uses.

Medium or large mussels are usually destined for pasteurization or the fresh market, while medium or small ones are generally used for canning in metal or glass containers. However, some customers use all types of sizes for canning in cans or jars, producing a wide range of valuable market products depending on the mussel size.

Mussel grading machines are essential for efficiently sorting sizes, allowing each group to continue along its processing line, ensuring a continuous flow.

Importance of classification for optimizing production

Classification not only facilitates the organization of the process but also optimizes resources. A well-classified mussel ensures a quality final product and improves the efficiency of the production line by working with the ideal sizes for each machine or for the desired final product.

Mussel Meat Extraction

Byssus removal: mussel debearder

The process for extracting mussel meat is practically identical for canning or freezing.

Industrial Mussel Cooking

Generally, mussels are cooked in a continuous cooker under the standards known as 90-90. This refers to the center of the product needing to be at 90 degrees Celsius for 90 seconds, ensuring it is properly cooked and meets food safety regulations.

In this cooking process, there is a critical point where the internal pressure of the cooker is released upon reaching a certain temperature, according to the cooking cycle. This sudden release of pressure helps open most of the mussels inside the cooker, facilitating the later extraction of the meat.

Shell and mussel separation by density and vibration

Upon completion of cooking, the meat and shell are expelled from the cooker simultaneously but need to be separated. The mussels then undergo a shell and mussel separation process using machines that leverage vibration and/or the differing densities of the products. Occasionally, these processes complement each other.

The density difference between the meat and shell causes the shell to sink to the bottom when both are submerged in brine, while the mussel meat rises to the surface. If there are shell fragments adhered to the mussel, the subsequent vibration process removes them. The meat eventually becomes detached and falls onto a lower-level conveyor.

Finally, a laminar flow of water removes small shell fragments that may still be stuck to the meat after the vibration separator. This way, using conveyors, all the meat converges in a final inspection area.

Finally, a manual inspection is performed to ensure that no impurities or small shells remain mixed with the meat. This step ensures a high-quality final product before canning or freezing.

Mussel Freezing Process

Upon obtaining the mussel flesh, the next step is to freeze it or preserve it in cans.

The initial freezing process is done using IQF freezing tunnels designed to prevent the meat from sticking together into blocks. These tunnels freeze individual units of mussel flesh to assure they remain separated. After freezing, the meat is classified into three or four different sizes. This classification is important to ensure the product is marketed according to different market demands.

After freezing, the glazing process is performed, which involves covering the mussel meat with a layer of cold water to protect it during storage in the cold chamber. This glazing using a water spray protects the product during storage and transport. Finally, the mussels are packed into boxes.

Mussel Preservation

Before packing mussels in cans, it is crucial to carry out a dehydration process.

During the initial cooking in the cooker, mussels lose some water, but not enough to prevent issues during canning. If the mussels contain too much water, it will be released during the sterilization process and mix with the marinade or sauces, negatively affecting the product’s presentation.

To resolve this, a dehydrator is used, subjecting the mussel to a thermal process at approximately 100 degrees for a few minutes, removing excess water. This process must be carried out by size, as smaller mussels require less dehydration time than larger ones.

Once again, confirming that good size classification throughout the process is crucial for optimizing the production line’s profitability.

Canning of preserved mussels can be done manually, especially for large and delicate mussels, or using volumetric systems for large production volumes. These volumetric filling machines ensure speed and precision in the weight required per can.

Once the mussels are canned, a covering liquid is added, usually a marinade, although it can also be salted water or other sauces. Subsequently, the cans are sealed, palletized, and sterilized in autoclaves. This process ensures that the product is safe for long-term storage, with a shelf life of several years.

This preservation process is highly efficient and adds great value to the final product, being one of the most popular presentations of mussels in the market.

Obtaining Half-Shell Mussels

Preparation: cleaning and brushing

To produce half-shell mussels, thorough cleaning is essential. After the classification and debyssing of the pieces, the shell is cleaned. This is done using a mussel brushing machine, which removes marine debris adhered to the shell, leaving it clean and with a good appearance.

Controlled cooking for shell opening

Mussels are cooked in a steam tunnel in a controlled manner to ensure the shell opens properly, facilitating the subsequent de-shelling process. These atmospheric cookers gradually increase the temperature to prevent shell blockage, which would otherwise leave the mussel closed and greatly complicate the manual shelling process.

Manual de-shelling and freezing

The manual shelling process separates the excess shell, leaving only the half-shell with the meat. This mussel then undergoes IQF freezing in spiral tunnels, ensuring that the shells do not stick together.

Glazing and presentation options

After freezing, the mussel on the half-shell is glazed to protect it during storage. It can be presented in trays, boxes, or vacuum packaging, ready for distribution in supermarkets or restaurants.

Mussel Pasteurization

Pasteurizing mussels is a delicate process that ensures full cooking and the elimination of microorganisms without altering texture or flavor. It’s usually done in vacuum bags or trays, ready for direct consumption.

In this case, the mussel undergoes the same cleaning, debyssing, and brushing process. Afterward, it is transferred to semi-automatic filling machines, where the mussel is weighed and dosed into bags or trays. They can be packaged without any sauce, cooking in their own juice, or accompanied by a recipe with sauces.

Differences with the canning process: times, temperatures, and shelf life

In contrast to the canning process, which involves sterilization at high temperature and pressure, pasteurization is performed at lower temperatures and pressures. This results in a product with a shorter shelf life, generally up to six months, compared to several years for sterilized mussels.

The difference lies in the number of microorganisms eliminated during the thermal process, with sterilization (at higher temperatures) achieving greater effectiveness and, therefore, greater product safety over time.

Use of continuous pasteuriser or autoclaves

The pasteurization process can be performed in a continuous pasteuriser, which maintains a constant product flow during the pasteurization cycle, or in autoclaves (discontinuous flow, by cycles). Both systems ensure that the mussel is pasteurized uniformly and effectively.

Storage and distribution options

After pasteurization, bags or trays can be refrigerated or frozen, depending on the client or the destination of the product. In some cases, the pasteurized product can be sent directly for distribution.

Preserving fresh mussels

This is the simplest process. To prepare fresh mussels, they are typically grouped in nets once they have been shelled, de-bearded, and their shells have been cleaned. These nets are then packaged and ready for sale in the fresh produce market.

This type of presentation has a very limited shelf life, usually between one to three days, making it the perfect choice for quick sales in markets or supermarkets.

Waste management: Shells

After separating the meat and shell, the shell waste is transported to silos located outside the factory. This is done using screw conveyors due to the abrasive nature of the shells, which can damage other types of conveyors such as modular belts or polyurethane and other plastic material belts.

Shell Crusher

The shells removed during the production process are managed through a system that crushes them before storage. This is done to optimize storage space, as crushed shells take up much less volume than whole ones.

A machine known as a shell crusher performs this process. Although not all factories choose to install this equipment, those that do can store more tons of shells in external silos before they are permanently disposed off.

Conclusion

The processing of mussels involves various techniques and stages that, with the appropriate mussel machinery, ensure a high-quality final product, such as canned mussels and half-shell mussels. Gaictech’s technology, a leader in the manufacture of canning industry machinery, ensures a high level of efficiency in the production line, reducing costs and maximizing output.

Distinctive value of Gaictech’s mussel machinery

The mussel processing generates very aggressive and corrosive waste, especially during cooking, so machines must be particularly robust. Gaictech’s machines are designed to withstand this aggressive environment by using high-resistance materials.

Specifically, Gaictech’s cookers are partly made from a special, high-quality stainless steel (SMO254) that is much more resistant than the standard steel commonly used in the industry (AISI316). This high-quality, resilient steel ensures that key parts of the cooker, such as the internal conveyor, last up to four production campaigns.

Thanks to the use of this material, Gaictech’s cookers require less maintenance, which translates into significant savings for customers. While other competing cookers often need key part replacements after each campaign, the use of more durable materials in Gaictech’s equipment provides a higher return on investment by reducing maintenance expenses.