What is the working principle of Blast Freezer?

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A Blast Freezer is a specialized category of freezer used to preserve food at a very low temperature to prevent the growth of microorganisms. A Blast Freezer is also known as Shock Freezer. In normal temperature, bacterial growth in food occurs at a  rapid, exponential rate. The food becomes unsafe for future consumption. The microorganism cannot thrive in the extremely cold environment of a Blast Freezer. A Blast Freezer is commonly used in food industry. Commercial kitchens use a Blast Freezer to preserve seafood, meat, dairy products, confectionaries, leftovers, and cooked foods. A Blast Freezer is commonly used in restaurants, catering unit, bakeries and ice-cream parlors. A Blast Freezer can reduce temperature of a food from +70?C to -18?C in less than 4 hours. Cost of a basic Blast Freeze can range between $5,000 to $35,000. Nowadays several models of automated Blast Freezers are available. These are provided with different energy saving, automatic defrost and noise reduction modes.


What is the history behind a Blast Freezer?

Till 1842,  food was preserved  by soaking in salt and ice brine. This method was commercially utilized till the advent of a mechanical refrigerator. In 1880, the first refrigerated frozen meat cargo was shipped from Australia to Britain. In the beginning of 20th century, quick freezing done by blowing air over food surface was found to highly effective. This led to the commercialization of the Blast Freezing method.


What is the working principle of a Blast Freezer?

In ordinary refrigerators, when a food gets frozen, the water inside it crystallizes. The crystals formed inside the food are relatively larger in size. However, a Blast Freezer promotes rapid freezing. As a result, very small crystals are formed inside the food.  When a large crystal melts, it ruptures the cells of the preserved food. Eventually the texture and taste of the food gets deteriorated. Blast Freezers are equipped with blowers to pass on chilled air over the food surface to freeze it down rapidly. Modern Blast Freezers are provided with movable trays for customizing foods' position for freezing. High volume of hot food should not be chilled in a Blast Freezer as it will increase the temperature of the freezer. In a conventional refrigerator, food is stacked one above another. The air circulating inside gets stagnated. The cold air pumped by the cooling coils has to cool both the stagnant air  and the food. That is the reason for which  ordinary refrigerator takes longer time to cool. However, a Blast Freezer has a different arrangement. In a Blast Freezer, there is always big space between the trays. Cold air is pumped continuously by the fans behind the racks in a smooth laminar fashion. There are different chilling modes in a Blast Freezer such as:

  • Soft Chill reduces the food temperature to +3?C.
  • Hard Chill reduces the food temperature to-15?C . Hard Chill is ideal for food products with high fat content such as broths, cut meat, and portioned meals.
  • Shock Freeze is used to reduce foods' temperature to -18?C within 4 hours.


What are the advantages of a Blast Freezer?

  • A Blast Freezer locks the color, texture, flavor, and nutritional value of the preserved food quickly.
  • Delicate preparations such as fruit extracts, soufflés, and pasta are protected from dehydration, and physical appearance damage with an 'ice skin' on the surface formed due to rapid cooling.
  • It inhibits microorganism growth and ensures 100% food safety.
  • When a food preserved in a Blast Freezer is thawed, its quality and structure remains in better form.
  • A Blast Freezer is provided with different food preservation compartments. Hence the risk of contamination is very low.
  • It is ideal for storing larger batches of leftovers. Thus it reduces food wastage and increase chef’s menu options for future use.


What are the disadvantages of a Blast Freezer?

  • A Blast Freezer is expensive and not ideal for domestic uses.
  • It consumes a lot of energy. Hence it is used in commercial units.
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