Application of immersion heaters in the cheesemaking industry

Cheesemaking involves fermentation and coagulation of milk, which then, through gentle agitation and separation of curd from the whey, results in cheese production.

The practice dates as far back as the Bronze Age and has been practiced by cultures worldwide. However, our ancestors encountered problems with certain cheeses because of using baskets to separate curd. Such cheeses would cause constipation or kidney stones, especially when taken in excess or with a combination of other foods like walnuts and almonds.

Fortunately, the process of making cheese has evolved over the centuries to ensure nutritious and safe cheese. However, this evolution has come at a cost; the process is much more complex and requires good equipment and a very high level of skill and precision. That said, here’s a brief description of the process and how immersion heaters have been employed within it.

Steps for making cheese

Although different cheeses require different processes, they all go through similar stages.

First, the milk is standardized to optimize the protein to fat ratio and make high-quality cheese with a high yield. Then, depending on the desired cheese, milk may be pasteurized or mildly heat-treated to reduce the number of spoilage organisms for an improved environment for the starter cultures to grow.

The starter cultures and any non-starter adjunct bacteria are added to the milk to allow ripening which develops flavor for the cheese. However, starter cultures require a temperature of 90ºF for optimal growth. Thus the pasteurized milk is cooled before they are added. It is then held at the said temperature for around 30mins. Aside from developing flavor, ripening helps to lower the pH of the cheese.

Rennet, which acts on the milk proteins to form the curd, is also added. During this step, the mixture is not disturbed until coagulum forms, which takes around 30 mins. When the curd reaches a pH of 6, it is taken out, cut into small pieces using cheese knives, and heated to 100ºF to separate the whey from curd through cheddar. This involves draining the whey and forming a mat from the curd, which is cut into sections that are piled on top of each other and flipped periodically. Cheddaring helps expel more whey and allows fermentation to a pH of between 5.1 and 5.5.

Some cheeses have to be put back in the vat and salted by either sprinkling salt on the curd or placing it in a brine.

Finally, they are placed in cheese hoops and pressed into blocks of cheese, which are then stored in coolers until the desired age is reached. This process takes months but can reach years in some cases. The cheese may then be cut and packaged into blocks or waxed.

Note that there are plenty of heating instances throughout cheesemaking. Here’s how immersion heaters are incorporated.

Application of heaters

The first application of immersion heaters is during pasteurization. Here most cheesemakers apply the flash pasteurization technique that’s different from superheating the milk. It involves heating milk for either 161.6°F for 15 seconds or 140°F for 30 minutes to eliminate the pathogenic microorganisms.

Others may use Thermalisation, which helps them avoid the pitfalls of heating pasteurized milk and raw milk since it’s not heated at such high temperatures. However, they still need to abide by the 60-day rule meaning that the milk must be aged for at least 60days at 35°F or higher to allow ample time for the cheese’s safeguard to combat any potential growth of harmful microbes since it’s technically raw milk.

The large-scale setups for these commonly include 200L tanks, often made from food-grade stainless steel, with motorized stirrers rotating at 25rpm with an outflow controlled by a butterfly valve. The heaters’ power is 2000W and is powered by 400V @ 50Hz, and is capable of maintaining the set temperature with an accuracy of between +/-35.6°F and +/-41°F.

Immersion heaters for these large-scale setups can be installed in one of three ways; the first is a direct insertion in the pasteurization tank, which is simple but still poses a challenge when replacing as it requires the tanks to be drained.

The second method is a more traditional method involving ‘over-the-side’ type immersion heaters. Although it’s the easiest to install and maintain, it’s outdated.

The last method involves using double jacket tanks. It is becoming more and more popular because of its ability to maintain high hygienic standards; water is used in the inner lining to heat the milk, thus keeping them separate.

For a home setup, you can get a portable immersion heater operating by 120V and between 5kW and 45kW.


Immersion heaters are crucial for cheesemaking. They are used in several process steps to provide precise heat to the mixture, creating ideal conditions for making quality cheese. But to work effectively, they themselves need to be ideal, which is why you need a reliable manufacturer on the job.

Rama Corporation has been designing immersion heaters for decades. If you’re looking for something custom for your cheese processes? Don’t worry, we got you covered. Contact us today to get a free quote on your next project.

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