01/03/2023 | Food & Beverage | 8 MINUTE READ

Measuring the Salinity of Brine in Freezers

brine frozen shrimp

Conserving different types of food over a lengthy period of time requires the right techniques and methods to ensure that the food doesn’t spoil or deteriorate too quickly. Seafood and other foods are known to be subjected to biochemical and respiration reactions that are catalyzed by enzymes. These reactions cause extensive deterioration to the foods unless they are properly stored.

There are a few food preservation technologies that you can decide to use, which include decreased water activity, fermentation, and thermal treatment, the latter of which includes the use of brine freezers. Some additional methods of conservation include high-pressure treatment, ionizing radiation, and treating with bactericidal gases.

Brine freezers have proven to be highly effective when used for the conservation of seafood since this solution allows for moisture to be properly retained. These freezers are useful because the salt/water solution can be kept at very low temperatures of around zero degrees Fahrenheit without freezing.

Even though the solution remains in liquid form, any food that’s placed inside will immediately begin to freeze. However, the solution’s salt content must be maintained to ensure that the solution doesn’t freeze, which is why measuring salinity is essential. The following takes a closer look at the importance of measuring the salinity of brine.


What Are Brine Freezers and How Are They Used?

Brine freezers are units specifically designed to accommodate the freezing of items in a brine solution. This form of refrigeration allows you to deliver a high-quality product that doesn’t have any sign of cellular damage that can occur with other freezing techniques. When using a brine freezing system, you can conserve fish for lengthier periods of time without needing to use ice. The food items are chilled uniformly for a more consistent temperature within.

In order to freeze food, a thermal exchange must be installed between the food product and the cold fluid. If the relatively warm product came in contact with the cold fluid, the fluid would be heated while lowering the product’s temperature. In the event that the fluid was kept in static contact with the food item, they would both eventually reach the same temperature, which would be at the halfway point between the food item and the cold fluid. At these temperatures, the food wouldn’t remain frozen and would quickly spoil.

Instead, brine freezers maintain the fluid’s temperature by circulating the solution around the product. The refrigeration system is designed to accommodate the extremely low temperatures. While there are a few other techniques that are just as effective as brine freezing, they are much more expensive and can involve everything from liquid nitrogen to impingement freezers.

When foods are placed in cold temperatures, the growth of microorganisms is slowed or inhibited. The same is true of damaging biochemical reactions. However, using freezing or deep freezing techniques results in the water being solidified. While the frozen products can be kept from spoiling for anywhere from a few months to a year, the quality of this product depends on how it’s frozen.

When water changes from a liquid state to a solid state, it expands, which can cause cell wall breakage to occur. This kind of damage allows for extracellular ice crystals to develop. When performing rapid freezing with brine freezers, small extracellular and intracellular crystals will form without damaging the food.

brine frozen food

What is Salinity?

Salinity refers to the concentration of dissolved salts present in water. Each body of water has different salinity levels. For instance, the Atlantic Ocean has the highest salinity levels of all five oceans. Seawater tends to have a salt concentration of around 3.5%, which is on the low end for brine solutions. Salinity can be measured as grams of salt for every 1,000 grams of water or as parts per thousand. Water that has a reading of 1.0 PPT would contain a single gram of salt for every 1,000 grams of water.

What is Conductivity?

Conductivity is the measurement of the ability that water has to pass an electrical current. Since inorganic chemicals and dissolved salts are able to conduct electrical current, the conductivity readings you obtain will increase as the salinity increases.

In comparison, oil and other organic compounds are unable to conduct electrical current properly, which means that their conductivity is low. Keep in mind that conductivity readings can also be altered by the water’s temperature. Warm water equals high conductivity measurements.

Conductivity is commonly measured to determine the quality of a water sample. Every body of water comes with a standard range of conductivity that can be used as a consistent baseline for future comparisons. Any large changes in the conductivity readings you obtain could indicate that a major pollutant has entered the water.

When looking specifically at brine freezers, a conductivity sensor can be used to determine if salinity levels are ideal. If the salt content is too low, the liquid solution could freeze, which would likely cause damage to the more delicate food that’s kept within.


How Brine Freezing Works

Brine freezing gives you the ability to freeze food at very low temperatures without needing to worry that the brine solution will also freeze. Adding salt to the water allows for the temperature of water to reach around -6 degrees Fahrenheit before freezing, which creates a eutectic system.

This system involves a mixture of elements of a single chemical composition that allows solidification to occur at a temperature that’s lower than all other compositions. The reaction that occurs when salt is placed into cold water is why this same solution is used to deice roadways during the frigid winter months.

How to Monitor Brine Salinity in Freezers

Brine freezing can be done in two simple steps. Let’s say that you’re using a brine freezer to store shrimp. The first step you’ll take in this process involves lowering the temperature of the shrimp to around 14 degrees Fahrenheit. From here, the product can be placed into an air blast tunnel to ensure that it reaches around zero degrees Fahrenheit. This process should only take between 20-120 minutes depending on the design of the tunnel you use.

By using the air blast tunnel before placing the product in the brine solution, the second phase of freezing can be completed at a much faster pace. The components that make up the brine solution extend to salt, water, sugar, and any additives you want to include.

The salt that you place in the brine solution should be standard sea salt. When used correctly, the salt will lower the freezing point of water. Once you’ve created a brine solution, it should be monitored to make sure the proper salt concentration is maintained. For consistent monitoring, it’s highly recommended that you use a conductivity sensor.

As was mentioned earlier, these sensors allow you to determine the salinity of a solution. If conductivity measurements are high, you can be confident that the solution contains a high amount of dissolved salts. On the other hand, low readings mean that the salt concentration should be improved before you attempt to use a brine freezer.

The Advantages of Brine Treatment

There are many notable benefits associated with using brine freezers for your food conservation needs, the primary of which is that flavor loss is kept to a minimum. The brine treatment that’s applied will allow you maintain the quality of the concentrate and the distillate, keep costs down, boost profits, reduce the time needed to obtain a return on your investments and enhance performance.

advantages of brine treatment


When you use brine freezing technology, the food you place in the solution will be thoroughly frozen without needing to worry about the cells being damaged. Treating the brine solution beforehand should allow for even better performance.

Quality of the Distillate and Concentrate

Adding each component of the brine solution separately allows you to maintain the quality of the distillate and concentrate, which gives you more control over how the system performs.

Cost and Profit

When you maintain the quality of the food that’s placed in the brine freezer, you should be able to deliver a fantastic product that can be sold at a better price. While standard freezing techniques are effective, they also cause more damage to the food, which results in more food being disposed. Less waste equals more profits.

Time Required for a Return on Investment

Brine freezers are a highly efficient method of freezing compared to the slow-freezing techniques that many companies use. By being able to freeze products at a quicker rate, you’ll spend less time and money on the process, which allows for a better return on investment.

Lowered Environmental Effect and the Economic Costs

If you properly treat brine solutions before discharging them, you’ll be doing your part to protect the environment and reduce the economic costs associated with environmental cleanup.

When you add salt to water, you can control when the solution will freeze, which is why measuring the salinity of your brine solution is essential with the brine freezing process. Obtaining precise conductivity measurements should help you maintain salinity levels.

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Posted by Dominic O'Donnell on January 3, 2023

Sensorex is a global leader in the design and manufacture of quality sensors for water quality and process applications. The company offers more than 2000 sensor packages for pH, ORP, conductivity, dissolved oxygen, free chlorine, chlorine dioxide, UV transmittance and other specialty measurements, as well as a full line of sensor accessories and transmitters. Its expert technical support engineers solve analytical sensor challenges with custom designs and off the shelf products.

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