Ice cubes
An ice cube is a technically produced small portion of frozen water ( ice ). Often, however, the shape does not correspond to that of a cube , but an uneven cuboid with an edge length of 2 to 5 cm, a cylinder , a sphere , more complex shapes such as stars, hearts, fruits, animals or undefined shapes.
history
Ice cubes have only become widespread since almost every household has at least a refrigerator with freezer compartment. Until the first third of the 20th century, ice was usually delivered to the home in the form of large cuboids ( stick ice or block ice). These were then stored in the refrigerator or cut into the required portions on site.
Refrigerators with an integrated ice cube maker and dispenser are available in stores.
use
The most common use of ice cubes is to cool food. Fish, meat and other perishable goods are kept fresh with ice cubes on their usually long transport route. Ice cubes are also used to cool drinks and are added directly to the glass or carafe. The cooling effect results from the temperature equalization between the ice and the food to be cooled, whereby the food becomes colder, while the ice cube warms up and melts after a certain time. The dilution of beverages by the melt water is a disadvantage of ice cubes compared to other means of cooling.
When mixing cocktails , the ingredients are often cooled in a cocktail shaker or in a mixing glass while mixing with ice cubes. Ice cubes are often crushed for cocktails and other drinks in order to enlarge the surface and thereby increase the cooling speed or to achieve a visual effect. One speaks then of crushed ice ( English for "crushed / crushed ice"). Chefs and bartenders use special devices with ice crushers .
In medicine, ice cubes are used to cool transplant organs on their long journeys from the donor to the recipient. The cooling stops the decomposition process .
In chemical laboratories, ice cubes can specifically cool certain processes, such as pyrolysis . So-called cold mixtures are prepared from crushed ice , since crushed ice has much better cooling properties than whole ice cubes, both locally and over a large area, and due to the greater degree of division it combines faster with table salt and other hydrophilic substances.
Manufacturing
Ice cubes can be made by pouring water into a mold and cooling it to below freezing point . The shape of the recesses in the ice cube mold determines the shape of the finished ice cubes.
Germs are not killed in the process. When traveling in tropical countries, it is therefore often recommended not to use ice cubes, as the water used may not have the usual hygienic standard. In May 2005, over 1,000 people in the Thai provinces of Lampang and Chiang Rai contracted hepatitis A because contaminated water was used to make ice cubes in a local ice factory . Even poorly cleaned ice compartments can lead to bacterial contamination of ice cubes, so that manufacturers of film packaging today offer ice cube bags in which water can freeze without further contact with air.
At first glance, it seems surprising that warm water freezes faster than cold water; this can be explained by the Mpemba effect .
There are ice cube machines for the automated production of ice cubes . Cloudy, cracked ice cubes are formed when the cubes freeze from the outside in. The liquid water trapped inside expands when it freezes and thus bursts the outer layers. Ice cube machines for the production of transparent, homogeneous ice cubes avoid this by solidifying the cubes around cooled pegs layer by layer from the inside out. Finally, the bowls or pens are briefly heated so that the ice cubes fall off. Most of the time you can see an indentation in the middle of these ice cubes. But there are also ice cube machines that can produce “real” whole ice cubes without cloudiness, for example from the manufacturers Hoshizaki or Kold-Draft.
During production in the freezer compartment, air pockets and cloudiness occur because the water surface and the sides freeze at the same time and the air is systematically displaced to the center and bottom of the ice cube. There it is finally enclosed in small bubbles that can be seen as white spots in the otherwise clear ice cube.
Ice cubes with air pockets
Cloudy ice cubes from an ice cube tray in iced tea
Formation of ice spikes when freezing
Melting ice cubes in a glass ( time lapse )
Cup-shaped machine ice cubes
Web links
Individual evidence
- ^ Travel and Infectious Diseases, Govi-Verlag Eschborn, 2004, pp. 192 and 213. ISBN 3-7741-0987-7 , preview in the Google book search
- ↑ Thailand. Ice cubes cause hepatitis ( memento from August 2, 2013 in the Internet Archive ), Stern (magazine) , May 26, 2005