Microstructure and Processing of Ice Cream

Ice cream and frozen desserts are popular throughout the world, but the United States is the largest consumer of ice cream. In the United States it is estimated that 46.8 pints per capita of ice cream and frozen desserts were consumed in 1992.Physically, ice cream is a foam in which the continuous phase is a partially frozen emulsion. Foams are also important for foods such as whipped toppings, souffle, mousse, meringue, and angel food cake. The structure of the foam affects the appearance, texture, consistency, lightness, and mouthfeel of these foods. A foam is mostly air and is characterized by high viscosity, low density, high surface area, and high surface energy. Food foams such as ice cream have an air content of 40-50% by volume. The continuous phase is a concentrated, unfrozen aqueous solution containing soluble milk salts, lactose, and added sugars. The dispersed solids (i.e., proteins, salts, stabilizer, and fat) are in the colloidal state and in the form of an emulsion. The ice crystals exist in the coarsely dispersed phase, occupying a major portion of the space between air cells.