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Ice Cream Machine
Ice cream makers have grown increasingly popular over the last few years. Not only do the results often taste better than shop-bought ice cream, but they allow you to control exactly what goes into your dessert, important for those who want to avoid additives, or are watching their calorie intake.
A domestic ice cream maker is a machine used to make small quantities of ice cream for personal consumption. Ice cream makers may prepare the mixture by employing the hand-cranking method or by employing an electric motor. The resulting preparation is often chilled through either pre-cooling the machine or by employing a machine that freezes the mixture. An ice cream maker has to simultaneously freeze the mixture while churning it so as to aerate the mixture and avoid ice crystals. As a result, most ice creams are ready to consume immediately. However, those containing alcohol must often be chilled further to attain a firm consistency.
Some machines, such as certain lower-priced countertop models, require the resulting mixture to be frozen for additional time after churning is complete. Some more expensive models have an inbuilt freezing element. A newer method is to add liquid nitrogen to the mixture while stirring it using a spoon or spatula for a few seconds; a similar technique, advocated by Heston Blumenthal as ideal for home cooks, is to add dry ice to the mixture while stirring for a few minutes. Some ice cream recipes call for making a custard, folding in whipped cream, and immediately freezing the mixture. Another method is to use a pre-frozen solution of salt and water, which gradually melts as the ice cream freezes.
There are three types of electric ice cream machines. Each has an electric motor that drives the bowl or the paddle to stir the mixture. The major difference among the three is how the cooling is performed.
Counter-top machines use a double-walled bowl with a solution between the walls (typically distilled water and urea) that freezes below 32°F or 0°C. In a domestic freezer, this requires up to 24 hours before the machine is ready. Once frozen, the bowl is put into the machine, the mixture is added and the machine started. The paddles rotate, stirring the mixture as it gradually freezes through contact with the frozen bowl. After twenty to thirty minutes, the solution between the double walls thaws, and the ice cream freezes. This type of machine has the advantage of being relatively inexpensive; however, a pre-frozen bowl makes only one batch at a time. The bowl must be refrozen to make another batch. Multi-batches require extra bowls for the machine, which require extra freezer space.
Small freezer-unit machines sit inside the freezer (or the freezer part of the refrigerator) and operate similar to a food processor in slow-motion. Every few seconds, the paddles stir the mixture to prevent formation of large ice crystals. When the ice cream sufficiently freezes, the paddles automatically stop rotating and lift. Since the mixture is cooled in the freezer, it takes longer to freeze than other ice cream makers, which work by placing the ice cream bowl in direct contact with the cooling element. A disadvantage is that the freezer door has to be closed over the flat cord, which is plugged into the nearest power outlet. However, some modern refrigerators have a built-in ice-cream maker as an accessory or a specialized electrical outlet for freezer-unit machines. It is not necessary to pre-freeze this type of ice cream maker. However, some people feel that this type of machine produces a lower-quality ice cream because of its slow-motion method. Also available are cordless, battery-operated ice-cream makers that may be placed directly in the freezer, although these tend to require expensive non-rechargeable potassium batteries (most rechargeable batteries or regular alkaline cells perform very poorly at low temperature).
More expensive, and usually larger, machines have a freezing mechanism built in and do not require a bowl to be pre-chilled. A few minutes after starting the cooling system, the mixture can be poured in and the paddle started. As with coolant-bowl machines, ice cream is ready in twenty to thirty minutes depending on the quantity and recipe. These machines can be used immediately with no preparation, and they make any number of batches of ice cream without a delay between batches. Some of these machines cannot be moved without waiting twelve hours before use since moving the unit upsets coolant in the freezing system. These machines are normally kept in a permanently position ready for use making them impractical in smaller kitchens.
The fourth type of electric ice cream maker uses an outer tub filled with ice and salt for chilling. An inner canister holds the ice cream mixture and churn and scraper assembly. A high-speed electric motor, geared at approximately 75RPM, drives a mechanism that simultaneously rotates the canister, counter-rotates the scraper and holds the churn paddles stationary. As the canister turns, the ice cream mixture freezes against the inner wall of the canister. The counter-rotating scraper constantly removes the frozen product from the canister wall and returns it to the mixture. The continuing turning motion of the canister against the stationary churn paddles causes the mixture to become increasingly thick. Enough time, ice and salt produces a smooth "hard packed" ice cream.
Ice cream (derived from earlier iced cream or cream ice) is a sweetened frozen food typically eaten as a snack or dessert. It is usually made from dairy products, such as milk and cream, and often combined with fruits or other ingredients and flavours. It is typically sweetened with sucrose, corn syrup, cane sugar, beet sugar, and/or other sweeteners. Typically, flavourings and colourings are added in addition to stabilizers. The mixture is stirred to incorporate air spaces and cooled below the freezing point of water to prevent detectable ice crystals from forming. The result is a smooth, semi-solid foam that is solid at very low temperatures (<35 °F / 2 °C). It becomes more malleable as its temperature increases.
The meaning of the term ice cream varies from one country to another. Terms like frozen custard, frozen yogurt, sorbet, gelato and others are used to distinguish different varieties and styles. In some countries, like the USA, the term ice cream applies only to a specific variety, and their governments regulate the commercial use of all these terms based on quantities of ingredients. In others, like Italy and Argentina, one word is used for all the variants. Alternatives made from soy milk, rice milk and goat milk are available for those who are lactose intolerant or have an allergy to dairy protein, or in the case of soy and rice milk, for those who want to avoid animal products.