The Biochemistry of Milk

The Complex Nature of Milk Milk supplies the calcium for building bones and teeth, especially during adolescence Milk is 87% water However that’s a solvent for over 250 chemical compounds, milk sugar (what is the name for milk sugar_____?____) water-soluble vitamins and trace minerals and salts

Protein Two main proteins make up milk: 80% Casein = milk protein 20% Whey = milk protein Micelles = an aggregation or cluster, of molecules, often found in colloidal dispersions The light reflecting from micelles makes milk white As long as milk keeps its normal acidity level, about pH 6.6, casein remains stable

Protein Continued When the pH level decreases the milk forms lumps or coagulates. Curds = The casein clumps that separate from the liquid when milk coagulates When cooking with milk you can prevent curdling by using starch to thicken the milk If you want to coagulate milk, you can use the enzyme rennin or vinegar. Whey = protein found in the liquid that remains after fat and casein have been removed from milk. Whey is also called serum protein

Fats Milk is an emulsion because small globules of fat (lipid) are dispersed throughout the water Creaming = process in which some of the fat droplets come together in larger clusters that rise and float to the top of the milk These clusters rise to the surface because fat is less dense than the watery portion of milk Cream = simply milk that is extra rich in emulsified fat droplets The fat in cow’s milk are most complex lipids, over 400 different fatty acids Click For Milk Experiment

Carbohydrate Lactose or milk sugar is the main carbohydrate Lactose provides food energy Also adds body to milk as well as a sweet flavor When milk is heated, lactose reacts with amino acids in the protein (giving cooked milk a slightly caramel flavor) When you consume milk, lactose becomes available to the body because of the enzyme lactase. This enzyme breaks lactose down into galactose and glucose, which is used in the body for fermentation during digestion.

Carbohydrate Continued Do you know someone who cannot drink milk??? People can be lactose intolerance = the inability to digest milk due to the absence of the enzyme lactase in the intestines People who are lactose intolerant cannot break down lactose in their body. When they drink the milk they can have bloating, stomach cramps and diarrhea.!!! -NOT FUN

Minerals and Vitamins Milk has salt that occurs naturally Salts in milk include chlorides and phosphates (in very low amounts) Salt in milk helps prevent curdling If an acid is added to milk (what would be an example of an acid), the pH lowers which removes the calcium ions from the casein, making the milk curdle Four vitamins found naturally in milk, riboflavin is found in the largest quantity. Breaks down when exposed to light