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.
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.
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: