Photo: Instagram @krantonsen

New knowledge about salt fish production

NORWAY
Friday, July 03, 2020, 05:20 (GMT + 9)

Now a salt status has been created for the salt quality used for clipfish and salt fish production, and how the salt can affect the finished fish product. A prototype for cleaning and washing salt for reuse has also been made.

The Norwegian saltfish and clipfish industry uses about 180,000 tonnes of salt annually, corresponding to a value of NOK 120 million. Salt is an important ingredient in these products. Attempts have been made in the past to study the quality of salt used for salting fish, but the results are neither comprehensive nor readily available. There has therefore been a need to summarize all existing knowledge, which is now done in the FHF project Knowledge status on salt for saltfish and clipfish production. The project is completed and led by Nofima. The project also aimed to create an overview of the requirements and regulations that apply to salt in the most important markets for Norwegian salt and clipfish.

Adding salt to cod is a method that can be traced all the way back to the 15th Century.There are a few different ways that fish can be salted – dry salting, brining or pickling

The Quality Regulations for Fish and Fishery Products require that the salt to be used for salting fish should be clean in appearance and not contain colored particles or foreign crystals. Furthermore, the salt is required to be free of an aberrant odor, and it must have a clear and pure salt taste. The iron and copper content should not exceed 10 and 0.1 mg / kg salt, respectively.

Photo: FHF

The salt composition changes after use

The results show that salt used for salting fish contains 97–98% salt, while the remainder consists of minerals. After the salt has been used, the salt composition changes and the salt composition affects the product quality. But the results also show that factors other than salt quality affect product quality, such as whether the raw material has been frozen and thawed and the temperature of the fish during salting. A fact sheet has been created in the project that summarizes these results. 

New technology for the purification and recovery of salt

Some companies have recently introduced mechanical purification of used salt after it was opened in the Quality Regulations in 2013. There is a great economic potential for the reuse of unsolved salt. Today, mainly used salt is dumped on the sea or buried. According to the researchers, it is realistic to assume that 40% of the salt can be reused. Today, the salt undergoes a washing process to recover the unsolved salt, but this is not satisfactory. Therefore, FHF initiated a project in the company Recycling salt and brine (ReSALT)led by Sintef Ocean in close collaboration with industry players. The project has developed a prototype salt purifier that has the potential to complete fully automatic cleaning of salt. The quality of the salt after purification meets the requirements of the regulations, but some adjustment and testing is needed before it can be commercialized.

Senior Scientist Grete Lorentzen. Photo: Lars Åke Andersen © Nofima

In order to clean brine, membrane filtration was tested in the project with good results. The investment cost of such a technology is reasonably high, but the potential for dividends is great.

The results of the project are summarized in a video: 

If this technology is used, it will have a significant impact on the environment as well as most likely to save costs in the long run.

Source: FHF – Norwegian Seafood Research Fund

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