Refrigeration

Lore & Background

The Persians stored ice in a pit called a Yakhchal and may have been the first to use cold storage to preserve food. In the 19th century, the rise of the ice trade enabled cold chains; Frederic Tudor harvested ice in New England and shipped it to the Caribbean and southern states, eventually turning a profit after constructing icehouses and using better insulated ships. Refrigeration is the artificial cooling of a space, substance, or system to lower and maintain its temperature below the ambient temperature. Early methods relied on consumable coolants like ice or dry ice, which required periodic replenishment.

Modern refrigeration is a self-sustaining heat exchanger process that transfers thermal energy against a temperature gradient using a working fluid, or refrigerant. Energy transfer can be driven by physical means, such as melting ice or an electromechanical machine, or by heat pumps, magnetism, electricity, or laser cooling. Heat pumps can utilize the heat output of refrigeration, such as for water heating, and may be reversible, functioning similarly to air conditioning units. Refrigeration has profoundly impacted human lifestyle, agriculture, industry, and settlement patterns.

The idea of preserving food by cold storage dates to prehistory, but for millennia, societies in tropical and most temperate regions relied on curing and drying, while cold storage was limited to arctic, subarctic, or alpine areas where natural ice or cool caves were available. The 19th-century ice trade enabled cold chains, and from the late 19th to mid-20th centuries, mechanical refrigeration was invented and expanded, leading to temperature-controlled rail cars, trucks, and ubiquitous home and store refrigerators. Refrigerated rail cars facilitated the settlement of areas not on traditional transport routes and enabled the growth of large cities in hot climates. In most developed countries, refrigeration is essential for food processing, distribution, and retail to maintain food safety.

Reader's Guide

The improvement in food preservation due to refrigeration significantly reduced food loss and waste due to spoilage, leading to a new supply chain infrastructure where large quantities of meat, seafood, and produce can be supplied from a smaller number of farms and fisheries. This has resulted in more diversification of food products available to the consumer market, affecting nutrition, tastes, and culinary arts. The introduction of refrigerated rail cars contributed to the settlement of areas not on earlier transport channels and sparked the building of large cities in hot climates such as Houston, Texas, and Las Vegas, Nevada. In most developed countries today, cities and towns are heavily dependent upon refrigeration in food processing, distribution, and retail industries to maintain food safety.