Ice cream is a colloidal emulsion made with water, ice, milk fat, milk protein, sugar and air. Water and fat have the highest proportions by weight creating an emulsion that has dispersed phase as fat globules. The emulsion is turned into foam by incorporating air cells which are frozen to form dispersed ice cells. The triacylglycerols in fat are non polar and will adhere to themselves by Van der Waals interactions. Water is polar, thus emulsifiers are needed for dispersion of fat. Also ice cream has a colloidal phase of foam which helps in its light texture. Milk proteins such as casein and whey protein present in ice cream are amphiphilic, can adsorb water and form micelles which will contribute to its consistency. The proteins contribute to the emulsification, aeration and texture. Sucrose which is disaccharide is usually used as a sweetening agent. Lactose which is sugar present in milk will cause freezing point depression. Thus, on freezing some water will remain unfrozen and will not give a hard texture. Too much lactose will result in a non ideal texture because of either excessive freezing point depression or lactose crystallization.
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