Bakers Journal

Having a blast

November 11, 2010
By Brandi Cowen

Freezing is a hot issue in the industry lately.

Freezing is a hot issue in the industry lately.

Many bakers and equipment manufacturers have been experimenting with new techniques for freezing, searching for methods that perfectly preserve a product without compromising quality. One of these is blast freezing. Here’s the lowdown.

A blast freezer uses a very strong compressor to force cold air over food until it reaches the desired temperature. Once the food is cooled, the freezer goes into holding mode and works like any other cold storage unit.


Whenever food is frozen, some of the water it contains is transformed into ice crystals, which can destroy the structure of a product. There is a critical temperature range for ice crystal formation between 0 C and 5 C. The time it takes food to pass through this zone has a huge impact on the number and size of ice crystals that form. A quick freeze, during which the product passes through this critical zone quickly, produces a large number of very small ice crystals, while a slower freeze produces a smaller number of larger ice crystals. This happens because the longer it takes for a product to truly freeze, the more time the water molecules have to come together to form ice crystals. These ice crystals are problematic in many foods, especially baked products like breads, cakes and muffins. Larger ice crystals pierce the cells in a product, affecting its structure, appearance and overall quality. That’s why blast freezing is inherently designed to preserve products better than traditional freezing techniques. The quicker freezing process forms significantly smaller ice crystals, minimizing the potential for ice crystal damage in the finished product.

Blast freezing also has an edge over other freezing techniques when it comes to food safety. The Canadian Food Inspection Agency (CFIA) says that temperatures below -18 C can stop the growth of many of the bacteria that cause foodborne illness. Because blast freezers bring temperatures down to this level (and lower) faster than other freezers, blast freezing halts bacterial growth sooner. This can be a huge advantage when working with eggs and unpasteurized dairy products that may be contaminated with salmonella. But, as the CFIA warns, freezing doesn’t kill bacteria; only proper cooking can do that.

Blast freezers are available in a variety of designs. The cost of a basic two-door model starts around $8,000, which is pricey compared to a basic two-door freezer that may sell for about $3,000. With all the different styles available, the various features different models include, and the options to customize a unit to suit your needs, prices can run high. If you decide a blast freezer is worth your investment, odds are there’s a model that suits your operation.

There are two ways blast freezers monitor the temperature of the products inside them. Some models have a timed chill cycle. Once the chill cycle has run its course, the freezer switches to holding mode and begins to operate like any other cold storage unit. Other models come equipped with sensor probes that are placed inside the food. When the probes register that the optimal holding temperature has been reached, they send a message to the freezer, instructing it to switch to holding mode. The best model for your bakery depends on what you plan on freezing, and whether inserting a probe will negatively impact your finished product.

Perhaps the most important consideration when thinking through your options is what size of freezer will best serve your needs. Purchasing and powering an overly large blast freezer is a waste of resources, but purchasing a freezer that’s too small and overstuffing it with product will produce substandard results. According to, one of the most common reasons for service calls on blast freezers is because a freezer isn’t cooling food quickly enough. According to the site, the problem usually isn’t with the freezer, but rather with staff cramming too much product inside, or improperly loading the unit.

Like any other process that relies on power, blast freezing can be hard on the environment. In addition to looking at energy requirements when purchasing a blast freezer, consider investing in products that can help green your investment from the inside out.

For example, Green Freeze Technologies has developed a line of heat exchangers made from food-grade stainless steel tubing. The Kinetic Energy Recovery Tubes (KERTS), which contain a proprietary thermal storage material, can be mounted near the ceiling of a fridge or freezer unit. When the compressor in your unit is running, the cold tubes attract heat from the air, lowering the temperature in the unit until it reaches the desired temperature. A programmable thermostat then turns the compressor off, and the KERTS release their cold thermal energy into the air to maintain a steady temperature. According to Green Freeze Technologies, KERTS can reduce your fridge or freezer’s energy requirements by up to 20 per cent.

There are also ways to green what goes into your blast freezer. Germany’s FkuR Kunststoff GmbH, a developer of several biodegradable plastics, has developed a sustainable, deep-freeze packaging solution made entirely from renewable resources. The company’s Bio-Flex line features three layers of compostable biofilms developed from biodegradable plastics.

As with any equipment purchase, be sure to ask a lot of questions. Find out from the manufacturer how much you can expect to pay to run and maintain the makes and models you’re interested in.  

As shelf-life stability and clean label continue to collide in the consumer-driven world of “free-from,” you can be sure freezing technology will continue to evolve. It’s worth keeping on your radar as a consideration for future investment and how your own products may or may not change in the marketplace.

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