From the Sea to the Factory: Reception and Initial Processing Stages of Mussels

Mussels are one of the most versatile marine products. Their flavor, texture, and cooking possibilities make them a highly popular food. Additionally, the various presentations of mussels for commercialization (canned, frozen, on the half shell, etc.) make this bivalve a highly valuable product for industrial exploitation.

In this article, we will focus on the initial stages of industrial mussel processing, where precision and efficiency are crucial to ensuring optimal economic performance.

Mussel Farming and Transport to the Processing Plant

Mussels are sourced from marine farms such as rafts (bateas) in regions like Galicia, Spain, or through systems known as long-lines, which are more common in other countries. These variations in farming methods influence the condition in which mussels arrive at the processing plant.

One of the key factors is whether any initial processing is carried out at the cultivation site. Some companies invest in basic machinery installed on work barges, enabling mussels to be detached on-site and sent loose to the processing plant. This pre-treatment involves detaching and washing drums that remove some of the marine debris, easing subsequent operations. However, not all farms use this approach. In many cases, mussels arrive at the plant just as they are harvested from the sea – in clusters, still attached to the ropes, with byssus threads and other marine residues.

When this pre-processing is not done at the source, the factory must undertake additional tasks. Mussels are received mixed and unsorted, in large bulk quantities. This situation demands more robust transport systems and machinery capable of operating in particularly dirty and demanding environments. Additionally, the initial work of detaching and cleaning requires more time, resources, and water, thereby affecting overall process efficiency.

In summary, the more pre-processing done at the source, the smoother and more profitable the initial treatment at the factory will be. Conversely, if mussels are received without any preliminary treatment, having a reception line equipped to handle high volumes of raw material becomes essential.

Mussel Separation and Washing

Once the mussels are brought into the plant, the first step is to detach and wash the mussels. This treatment is crucial when mussels arrive in clusters, meaning they are together and attached by byssus threads and marine debris after harvesting. The purpose of this step is to separate individual mussels and remove debris and undersized mussels, which are out of size range, before continuing with processing.

For this purpose, a mussel declumper is used. In the case of Gaictech, it consists of two main modules. The first module is the detaching drum, which is responsible for separating the clusters and releasing individual mussels. Once detached, the mussels proceed directly to the second module, which is the washing drum.

In this second stage, with a large amount of water – which can be fresh or saline, depending on the plant’s system – marine residues such as algae, stones, byssus threads, and other impurities are removed. Additionally, undersized mussels, typically smaller than 14-15 millimeters, are filtered out.

All water used for washing is managed through filtration systems. In plants close to the sea, the saltwater utilized can be discharged directly into the marine environment. For freshwater, a filtration and recirculation system is generally applied to reduce consumption, since these machines require intensive water use.

This initial process of mussel degranulating and washing standardizes the product, removes debris, and prepares the raw material for size classification. The machinery involved plays a key role in ensuring the quality and cleanliness of the mussels from the beginning of the process.

Mussel Classification by Size: a Crucial Phase

Next, the mussels are classified by size to facilitate their subsequent processing and to tailor them to the different final products that will be elaborated upon later. This phase is critical not only for improving the overall efficiency of the line but also for ensuring an adequate presentation of the final product.

Once cleaned, the mussels undergo a classification process using a grading machine that employs a system of divergent rollers with a specific design. In the case of Gaictech, this equipment allows the separation of mussels into at least three different size categories. Each of these sizes is directed to a distinct section of the processing line, as their destination and further handling differ.

Size separation not only optimizes line efficiency but is also essential for the various uses of mussels. For instance, large and medium sizes are often used for processes such as bag pasteurization, the production of frozen half-shells, or the fresh market. Meanwhile, smaller mussels are mainly used to obtain meat which is then either frozen or canned. These uses can logically vary depending on the needs of each factory or the market they aim to target.

In cases where mussels are destined for canning, all three sizes can be utilized based on the type of presentation required. In other processes, such as third-party freezing, a clearer differentiation is made, as some sizes remain in the plant for further processing while others are sold directly.

Conclusion

The first stage of mussel processing —which includes reception, declumping, washing, and classification— forms the foundation upon which the entire production line is built.

Having automatic, efficient, and precise machinery at this stage not only allows for processing large volumes of raw material swiftly but also ensures adequate preparation of the mussels for subsequent processes, reducing time, waste, and costs. The automation and durability of the equipment involved are especially critical when working with a raw material like mussels.

Investing in a well-designed and balanced production line from the start improves overall performance and guarantees the quality of the final product, regardless of its commercial destination.