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Chapter 34
Control by Low temperature
introduction
The effectiveness of low temperature, especially freezing, in food preservation was probably recognized by our ancestors at least in the last Ice Age, before 40,000 b.c. Natural freezing and
thawing could also have been used to preserve food during the very early stages of civilization in
approximately 10,000–12,000 b.c. In the colder regions of the world, foods (e.g., meat and fish)
are still preserved in natural ice. Ice was used by the wealthy Romans to reduce the temperature
of foods. Until approximately a.d. 1800, ice blocks from frozen lakes were cut, stored, and used
to preserve raw foods (e.g., meats, milk, fish, and produce) by lowering the temperature. By 1840,
with the help of ammonia-compressed refrigerator units, ice blocks were produced commercially
and used to reduce the temperature of food for preservation. In 1880, refrigeration was used on
ships and trains in Europe to transport meat and fish from other countries. Linde, in Germany,
developed the first domestic refrigerator in approximately 1874 and started commercial production before 1890. The popularity of domestic refrigerators was initially slow in the United States;
in 1930, 2%–3% of the households had the units. In the United States, methods to freeze fruits
and vegetables were developed and commercially used around the 1930s. During this time, retail
stores also started using cabinets to display frozen foods.
During World War II (1941–1944), consumer interest in refrigerated and frozen foods
increased dramatically, which helped develop the technology necessary for processing, transporting, retailing, and home storage of refrigerated and frozen foods in the United States. The popularity of refrigerated and frozen foods has increased steadily since then. In the 1960s, 1970s, and
early 1980s, frozen food consumption increased sharply, mainly because of the long shelf life.
Since the mid-1980s, there has been increased interest in refrigerated and chilled foods, which
consumers view as natural and healthy. The major drawback of many refrigerated foods is their
relatively short shelf life, approximately one to two weeks. But in recent years, several technological improvements, such as oxygen-impermeable packaging materials, good vacuum-packaging
equipment, innovative packaging systems, low-temperature refrigeration units (≤–1°C), and use
of the hurdle concept to preserve food (Chapter 41) have helped increase the shelf life of many
refrigerated foods to 60 days and, for some products, to more than 90 days. At present, of the
total foods consumed, low-temperature preserved foods constitute more than 65%, and the trend
Chapter 34
Control by Low temperature
introduction
The effectiveness of low temperature, especially freezing, in food preservation was probably recognized by our ancestors at least in the last Ice Age, before 40,000 b.c. Natural freezing and
thawing could also have been used to preserve food during the very early stages of civilization in
approximately 10,000–12,000 b.c. In the colder regions of the world, foods (e.g., meat and fish)
are still preserved in natural ice. Ice was used by the wealthy Romans to reduce the temperature
of foods. Until approximately a.d. 1800, ice blocks from frozen lakes were cut, stored, and used
to preserve raw foods (e.g., meats, milk, fish, and produce) by lowering the temperature. By 1840,
with the help of ammonia-compressed refrigerator units, ice blocks were produced commercially
and used to reduce the temperature of food for preservation. In 1880, refrigeration was used on
ships and trains in Europe to transport meat and fish from other countries. Linde, in Germany,
developed the first domestic refrigerator in approximately 1874 and started commercial production before 1890. The popularity of domestic refrigerators was initially slow in the United States;
in 1930, 2%–3% of the households had the units. In the United States, methods to freeze fruits
and vegetables were developed and commercially used around the 1930s. During this time, retail
stores also started using cabinets to display frozen foods.
During World War II (1941–1944), consumer interest in refrigerated and frozen foods
increased dramatically, which helped develop the technology necessary for processing, transporting, retailing, and home storage of refrigerated and frozen foods in the United States. The popularity of refrigerated and frozen foods has increased steadily since then. In the 1960s, 1970s, and
early 1980s, frozen food consumption increased sharply, mainly because of the long shelf life.
Since the mid-1980s, there has been increased interest in refrigerated and chilled foods, which
consumers view as natural and healthy. The major drawback of many refrigerated foods is their
relatively short shelf life, approximately one to two weeks. But in recent years, several technological improvements, such as oxygen-impermeable packaging materials, good vacuum-packaging
equipment, innovative packaging systems, low-temperature refrigeration units (≤–1°C), and use
of the hurdle concept to preserve food (Chapter 41) have helped increase the shelf life of many
refrigerated foods to 60 days and, for some products, to more than 90 days. At present, of the
total foods consumed, low-temperature preserved foods constitute more than 65%, and the trend