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. Production Before the development of modern refrigeration, ice cream was a luxury reserved for special occasions. Making it was quite laborious; ice was cut from lakes and ponds during the winter and stored in holes in the ground, or in wood-frame or brick ice houses, insulated by straw. Many farmers and plantation owners, including U.S. Presidents George Washington and Thomas Jefferson, cut and stored ice in the winter for use in the summer. Frederic Tudor of Boston turned ice harvesting and shipping into a big business, cutting ice in New England and shipping it around the world. Ice cream was made by hand in a large bowl placed inside a tub filled with ice and salt. This is called the pot-freezer method. French confectioners refined the pot-freezer method, making ice cream in a (a covered pail with a handle attached to the lid). In the pot-freezer method, the temperature of the ingredients is reduced by the mixture of crushed ice and salt. The salt water is cooled by the ice, and the action of the salt on the ice causes it to (partially) melt, absorbing latent heat and bringing the mixture below the freezing point of pure water. The immersed container can also make better thermal contact with the salty water and ice mixture than it could with ice alone. The hand-cranked churn, which also uses ice and salt for cooling, replaced the pot-freezer method. The exact origin of the hand-cranked freezer is unknown, but