What is a Blast Freezer?

Mary McMahon
Mary McMahon

A blast freezer is a freezer which is extremely cold. It may also be known as a shock freezer. Such freezers are intended to rapidly bring the temperature of foods down, freezing them extremely quickly. These specialized freezers are used in the frozen food industry for everything from ice cream to television dinners, and they are also utilized in some commercial kitchens for specialty tasks.

Blast freezers are used by the food industry to initially freeze microwavable TV dinners.
Blast freezers are used by the food industry to initially freeze microwavable TV dinners.

When food is frozen, the water inside it crystallizes. If freezing takes place at relatively warm temperatures, the ice crystals which form will be large. In a blast freezer, the extremely cold temperature promotes very rapid freezing, which creates small ice crystals. The smaller the crystals, the less damage to the food, as large crystals can rupture cells. Once the food has been frozen, it can be moved to a more conventional freezer for storage, as long as the freezer stays cold enough to keep the food frozen.

Many blast freezers operate with blowers which force chilled air over the food in the freezer to cool it down rapidly. Others may operate differently, depending on the design. These freezers can be equipped with movable trays for positioning foods, and they may also include an assortment of compartments for freezing. The freezer can usually handle foods which are chilled, at room temperature, or hot, as long as it is not overloaded; too high a volume of hot food, for example, can cause the temperature in the blast freezer to rise.

There's another advantage to blast or shock freezing, beyond the preservation of the integrity of the food. Extreme cold inhibits bacterial growth, which means that if food is handled safely and then placed immediately in the freezer, the likelihood of contamination is very low. This increases food safety, making such freezers popular in commercial food preparation to reduce the risk to consumers.

Blast freezers tend to eat up a lot of energy, which is why they are most commonly seen in industrial and commercial applications. Household cooks can use a blast freezer as well, if they have a need for it. For example, some hunters like to use a blast freezer to freeze meat once it has been butchered, and cooks who prepare a lot of dishes for future use, such as lasagnas, may also prefer the quality of shock frozen food.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


Can someone help me to find the procedures for the correct way to use a blast chiller? I've a very large quantity of food and I need to open the chiller door often to add more food. Is this wrong? If yes, why and which procedures say this?


I am a refrigeration laboratory technician and would like to have access to blast freezer parts.


I need advice and to get information from you. Should a blast freezer be totally sealed off during blasting? Is it advised that the door should not be open during blasting because you need to put in the product during blasting. --C. Lim


Not all bacteria die during freezing; they can be damaged, die or stay viable. Parasites however, if following proper freeze time/temperature guidelines, can be killed. Freezing bacteria is the equivalence of hitting the pause button! Microbiology labs freeze pure cultures into small vials at -80C.


@ ValleyFiah- You can find different blast freezers online. You can also contact manufacturers like Hobart, Electrolux, and others to find out about dealers for their models.

Your best bet may be to look for a used blast freezer. A new blast freezer can easily run for $10,000+, but a used freezer will only run you half the cost. Commercial quality blast freezers are also relatively easy to maintain, usually costing no more to maintain than a walk-in or commercial refrigeration unit. You can find used blast freezers at restaurant supply auctions or at sites like eBay.


I own a small restaurant and I would like to make my own gelatos to serve in the restaurant. I also would like to be able to freeze locally produced seasonal products and seafood so that they can be used on the menu during the off-season and winter months. Where can I find a blast freezer for sale? How much does a blast freezer cost?


Premium sashimi or sushi grade seafood is often frozen in a commercial blast freezer. Freezing fresh ocean fish at a temperature below -31 degrees Fahrenheit for more than 15 hours will kill all bacteria and parasites present in the fish. As the article stated, the fish will also resemble fresh caught seafood because the ice crystals will do less damage to the flesh.

If you enjoy sushi, you should always look for fish that is frozen in a blast freezer. You should never eat "fresh" fish raw, unless you eat it within two hours of being caught.

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