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ULT freezers for fish

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Alex Henderson

Aston Business School graduate who has been the Managing Director of Henderson Biomedical since January 2015. Passionate about helping laboratories keep their vital equipment operational and compliant. Architecture enthusiast, fitness fanatic and dog lover!

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Laboratory instruments, such as centrifuges and heat sealers can be used for a variety different applications. These applications are not always restricted to the scientific world. Ultra-Low Temperature (ULT) freezers, are also like this, as they can be used for both clinical and non-clinical applications. A good example can be seen in the food and restaurant sector. It is becoming increasingly common for top chefs in restaurants to use ULT freezers for deep freezing fish. This could be general fish such as cod or hake, or it could be more specialist fish dishes such as sushi. Let’s take a look at some of the reasons why:  

Freezing fish at ultra-low temperatures

The food we consume is mainly comprised of water. Fish is no different. It is estimated that the water content of raw fish is around 70%.

When a piece of fish is placed in a freezer, the molecules of water inside the flesh turn into crystals. These crystals then connect with other nearby crystals. When a fish is frozen in a conventional freezer (by that we mean at around -18°C), this crystallisation process can take some time. During this period, more crystals join together to form larger crystals. These larger crystals can often puncture the cells of the flesh. This means liquid content inside the cell will be released when it is eventually defrosted. Consequently, this has a negative effect on the overall texture of the fish.

The diagram below summarises this:

ULT freezer for fish vs conventional freezing
ULT freezing for fish Vs conventional freezing

Conversely, by using ULT freezers for fish, you are freezing the fish as a much faster speed to a lower temperature (usually between -40°C to -60°C). You are essentially ‘flash freezing’ the flesh, minimising the crystallisation process and thus avoiding the risk of puncturing the cells.  This preserves the original texture of the fish and results in a much better taste when the fish is defrosted for consumption.

ULT freezers for storing fish

As already mentioned, we can store fish in a ULT freezer between -40°C to -60°C. Freezing fish at this temperature helps to preserve the organoleptic qualities of the flesh. However, there is another advantage. By freezing at ultra-low temperatures, restauranteurs are able to store fish for much longer periods of time. For example, flat fish such as plaice and sole can be stored for 9 months at -18°C, but can be stored for 2 years if frozen at -30°C. This allows restaurants to better manage their supply chains. Restauranteurs can bulk buy or stockpile certain types of fish at different times of the year when supply is good. This ensures a good supply of all types of fish, all year round. Furthermore, by buying fish further in advance, restaurants can better protect themselves from nasty price rises due to supply issues.

How Henderson Biomedical can help

We supply a range of ULT freezers in different sizes to a variety of different markets. Of course, our core business is within the scientific field. However, we do also supply ULT freezers for other uses, including in the food sector. We can offer brands such as Vestfrost, which are already very well known in both science and food/beverage markets. Whilst brands like Nuve are also offer a competitively priced ULT freezer that can be used for many different applications.

In addition to this, Henderson Biomedical can also offer a number of complimentary products used in the restaurant and catering sector such as wireless temperature monitoring, ice makers and refrigerators.

For more information on what we can offer and how we can help you, please contact our team on 020 8663 4610 or email us at

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