Milk is more than just a refreshing drink that is a chemical cocktail also fascinating. Two important components of milk are a protein called casein and sugar in a call to lactose.The extraction of these components is a popular experiment in laboratory grade classes because it shows some of the methods that use chemicals to extract specific compounds from plants and other natural products.
Chemistry of Milk
Usually the fats oils do not dissolve in water.Milk, however, contains fat stored in countless small globules. Molecules such as phospholipids and specific proteins in milk are hydrophilic or andquot; likingandquot water, and a hydrophobic region or andquot; dislikingandquot water; region. These amphipathic molecules called surround the fat globules and allowed to mix with water. The globules are less dense than water, however, if the milk is left to stand for sufficient time, many of them will rise to the surface and create a layer of cream can skim the top.
The casein and lactose
Lactose is a disaccharide or two for a package formed by two simple sugars, but readily dissolves in water. It is less soluble, however, in a water-ethanol mixture, and may be crystallized from a solution of this type. Casein, however, is actually a mixture of three proteins, two of which dissolve poorly in water. As the fat globules, these proteins are stabilized by water-soluble protein third with negatively charged phosphate groups attached to some of its amino acids. If the pH of the milk falls below 4.6, the phosphate groups are hydrogen ions pick up and lose their negative charge and casein is precipitated or dropped out of solution.
Acid
To isolate casein may be added dropwise acetic acid to the hot milk. Casein is precipitated and can be removed with a spatula. It is important not to add too much acid, however, because if the pH falls too low, which will split the lactose to glucose and galactose. Once the casein is removed by heating the mixture to a still higher temperature makes albumin proteins have also found the milk to lose its structure and precipitate.
The crystallization of lactose
Centrifuging the heated milk albumin ensures all eliminated. A centrifuge is a relatively simple device that rapidly rotating tubes positioned in a rotor throwing outwards content of dense precipitate and deposition of liquids in the mixture. Can then add ethanol and heat the milk, the temperature is maintained higher than the precipitation lactose, while centrifuging the mixture, the removal of other compounds that may contaminate the product to lactose. Leaving the resulting mixture to precipitate for a few days lactose yields of sugar crystals.
