Top Ice cream definition history production britannica

Iced desserts were introduced into Europe from the East. Marco Polo brought back descriptions of fruit ices from his travels in China. Italian cooks developed recipes and techniques for making both water and milk ices; Buontalenti, one of the cooks taken to France by Catherine de Medici, first prepared such treats for the French court. In 1686 a Sicilian, Francesco Procopio, opened a café in Paris and began to sell ices and sherbets, which became so popular that numerous other ice makers soon opened in the capital. Tortoni, owner of a café in late-18th-century Paris, is credited with developing cream ices. In the United States, ice cream was served by George Washington, Thomas Jefferson, and Dolley Madison. Philadelphia became the hub of ice-cream manufacture in the United States; the ice-cream soda was invented there in 1874. The ice-cream cone, portable and self-contained, originated at the 1904 World’s Fair in St. Louis, Missouri, U.S.Commercial ice cream is made by combining, under constant agitation, the liquid ingredients (milk, cream, syrups, etc.). These liquids are heated and combined with dry ingredients (sugar, stabilizers, dried eggs or milk) to form a mix, which is then pasteurized and homogenized. The mix is ripened for several hours in a refrigerated vat, then combined with finely chopped fruit, nuts, or other solids. The mix is agitated while being frozen in order to incorporate air and control the size of the ice crystals that are formed. The partially frozen ice cream is drawn off into packages and frozen solid, or “hardened.” So-called soft-service ice cream was invented in 1939; it is served directly from the freezing machine without being allowed to harden.Homemade ice cream is often made with a base of boiled custard. The mix, with flavourings, is poured into a canister surrounded with ice and salt or a refrigerator unit. The contents of the canister are agitated by means of a hand crank or electric motor until the ice cream is softly frozen. The ice cream is usually allowed to harden further in a freezer.mechanical system, Any building service using machines. They include plumbing, elevators, escalators, and heating and air-conditioning systems. The introduction of mechanization in buildings in the early 20th century brought about major adjustments; the new equipment demanded floor space, and the design team began to include electrical and HVAC (heating, ventilating, and air-conditioning) engineers. Heating and cooling changed dramatically.Modern buildings, with their large heat gains, turned central heating into little more than a supplement. Heat removal is a much more serious burden, especially in warm weather. The roofs of high-rises are occupied by cooling towers and mechanical penthouses; entire floors are often dedicated to the containment of blowers, compressors, water chillers, boilers, pumps, and generators.cooling system, apparatus employed to keep the temperature of a structure or device from exceeding limits imposed by needs of safety and efficiency. If overheated, the oil in a mechanical transmission loses its lubricating capacity, while the fluid in a hydraulic coupling or converter leaks under the pressure created. In an electric motor, overheating causes deterioration of the insulation. The pistons in an overheated internal-combustion engine may seize (stick) in the cylinders. Cooling systems are employed in automobiles, industrial plant machinery, nuclear reactors, and many other types of machinery. (For a treatment of cooling systems used in buildings