A blast chiller freezes food by using a fan inside a traditional refrigerator or freezer to circulate the cold air. The blast chiller can cool food up to three times faster than a regular refrigerator or freezer. Speed is essential to avoid the formation of large crystals of ice which can damage food and to cool food faster than bacteria can grow. Blast chillers in 2011 cost from $5,000 for a countertop model to $35,000 for a restaurant grade walk-in blast chiller.
Components of a Blast Chiller
The basic refrigerator or freezer has a place to stack food, often one atop another, and a cooling system. Stacked food is insulated on the top and bottom and takes longer to cool. Air around the food is stagnant. Cold from the cooling coils has to cool the stagnant air then cool the food. In addition, new food items add heat inside the freezer or refrigerator. Stagnant air allows this new, warm air to stay next to other food. A blast chiller substitutes a number of trays in which food is separated into a single layer for the big space in which food is stacked. Cold air is drawn over the food from fans at the back of the racks in a smooth laminar flow.
Lean meat is approximately 70 percent water. Slow freezing results in the formation of large ice crystals which damage proteins within the meat and cause a loss of elasticity, water-holding capability and reabsorbtion. Meat should be thawed slowly in the refrigerator, allowing the ice crystals to melt with minimal damage to the meat. Also, bacteria growth is slower when meat is thawed inside the refrigerator.
Bacteria grow from two to 12 times faster in temperatures between 45 degrees Fahrenheit and 140 degrees Fahrenheit than in temperatures colder than 45 degrees Fahrenheit. Blast freezing speeds food through this danger zone. The United States Department of Agriculture recommends that food stored in a bowl or package 2 inches thick should freeze in two hours. In a walk-in freezer, a container with two inches of beef stew takes 12 hours to to get to a temperature of 38 degrees Fahrenheit from room temperature.
The Cost of Blast Chillers
The website, Shopping.com, lists blast chillers from $4,530 to $34,558 in 2011. The lower cost models are built to rest on a counter top. The expensive model features a roll-in ramp, three chilling functions and three chilling modes and holds 200 pounds.