The Purpose of Refrigeration

• Refrigeration slows bacterial growth in food and beverages. Bacteria, which are everywhere, thrive in a warm environment and can cause serious illness. According to the U.S. Department of Agriculture, ideal temperatures for bacteria growth are between 40 and 140 F. In such an environment, some bacteria will double within 20 minutes. A refrigerator set at 40 F or below will significantly slow this process and protect the majority of foods.
  
  

Early Preservation

• Man has attempted to preserve food since prehistoric times by storing meat in caves or snow. In colder climates, ice was harvested and stored for use in the warmer months. Krasner-Khait writes that by the 17th century, France was using ice to create cooled drinks such as iced liquors and frozen juices. Others stored perishables such as milk and butter in cellars, lakes, streams, or wells. However, the food was often prone to spoilage during the warmer months. Salting, spicing, smoking, pickling and drying were popular methods for combating spoilage.
  
  

Manufacturing Ice

• The use of ice became prevalent by the early 19th century. Frederick Tudor developed insulating materials for storing and transporting ice. By the late 19th century, most homes had an icebox. Natural ice was extracted and shipped throughout America. By 1879, there were 35 commercial ice plants in America. However, as natural ice eventually proved problematic, due to pollution and sewage, mechanical refrigeration took hold.
  
  

Refrigeration Emerges

• Over time, the leakage of refrigerants such as ammonia (NH3), methyl chloride (CH3Cl), and sulfur dioxide (SO2) proved deadly. In 1928, Thomas Midgley Jr., assisted by Albert L. Henne and Robert Reed McNary, invented freon as a substitute for the harmful refrigerants. Freon was eventually determined to be harmful to the ozone and was replaced with HFC 134a in 1996, which is used today.