Milk+Madness

__** MILK **__
Milk is a mixture of substances. We can change milk into other products. These changes can be physical eg: when making ice cream or butter, or chemical,eg: when making yogurt or casein.

The main substances in milk are water, fats (including butterfat), proteins, milk sugars (including lactose), and minerals. Milk also contains small amounts of other substances, such as pigments or colouring, enzymes, vitamins, gases and phospholipids (substances with fatlike properties).

Milk consists of about 87% water. The other 13% of milk is made up of solids, which are known as ‘dry substances’. The exact amount of each substance varies among cows of different breeds and among other milk producing animals.

If full cream milk is left to stand, it separates into two layers- skim milk and cream. The layer of cream forms on the surface because it is less dense than the skim milk. (This is rather like floating oil on the surface of water.) Cream contains spherical fat globules of various sizes, which float in the milk. Each sphere has a thin ‘skin’ made of proteins and phospholipids. These protect the fat from being attacked by the enzymes in the milk. Although small, the fat globules are the largest particles in milk, numbering about 3000 to 4000 in every millilitre.

Many consumers dislike milk separating into creak and skim milk. To prevent the fatty components from separating out and floating to the surface of a bottle or carton, the milk can be homogenised. This is achieved by forcing the milk through a fine filter. In this process the fat globules are mechanically broken down into smaller globules that will spread evenly through the milk.

Milk can be treated in many ways to produce a large number of other products.

Raw milk can contain a variety of disease causing organisms. Pasteurisation kills these organisms be exposing them to heat levels that they cannot survive. After the full cream milk has been pasteurised it may be separated into skim milk and cream. Each component can be manufactured into different types of dairy product.

__**Milk on the Move**__

media type="youtube" key="6T3C-0-Djas?rel=0" height="480" width="853" Detergent molecules have two ends, one end is attracted to water, and the other end is attracted to fat.

**What you need:** Milk Food colouring Shallow dishes Detergent Eye-droppers or straws

**Method:** 1. Pour thie milk into a dish to a depth of about 1cm. 2. Using an eye-dropper or straw, add a few drops of food colouring to the milk in different places. Using a seperate eye dropper or straw, add a drop of detergent into the middle of the milk.

**Variables:** Change this experiment by trying different types of milk. How does the reaction differ?

Record your results on your form.

__**Ice Cream Capers**__ Legend has it that the Roman emperor, Nero, is credited as the first person to make ice cream. Nero commanded slaves to bring snow down from the mountains, which was then used to freeze the flavored cream mixture. The secret was to lower the freezing point of ice in order to freeze the cream. How? The scientific secret is salt! Here’s a scientific recipe that you can use at home to make your own ice cream.

media type="youtube" key="OslIVjv0MiY?rel=0" height="480" width="853" **Materials:** 1 large zip lock plastic bag 1 smaller zip lock plastic bag 200 grams salt 120 ml milk 20 grams sugar 1/2 teaspoon vanilla essence 1kg crushed ice Ice cream container

**Procedure:**
 * Fill the large plastic bag about half full with crushed ice.
 * Add about 200 grams of salt to the ice. Seal the large plastic bag and shake the ice and salt for about five minutes.
 * Use one small-size zipper-lock bag to mix the following ingredients:Seal tightly, allowing as little air to remain in the bag as possible. Too much air left inside may force the bag open during shaking.
 * 120 ml milk
 * 20 grams sugar
 * 1/2 teaspoon vanilla extract
 * Place the small bag inside the bag with the ice and seal the bag. Put both bags inside the ice cream container and seal.. Shake, rock, roll, and mix that can! Your ice cream should be ready after about 15-20 minutes.
 * Once mixed, remove the inner bags from the container and rinse them well with water. You don’t want any salt water accidentally getting into your ice cream.
 * Once mixed, remove the inner bags from the container and rinse them well with water. You don’t want any salt water accidentally getting into your ice cream.

Repeat this experiment without the ice. What differnece does this make to the ice cream consistency? The length of time it takes to make the icecream?

**//What does the salt do?//**
Just like we use salt on icy roads in the winter, salt mixed with ice in this case also causes the ice to melt. When salt comes into contact with ice, the freezing point of the ice is lowered. The lowering of the freezing point depends on the amount of salt added. The more salt added, the lower the temperature will be before the salt-water solution freezes. For example, water will normally freeze at 0 degrees C. When salt is added to the ice (or snow), some of the ice melts because the freezing point is lowered. Always remember that heat must be absorbed by the ice for it to melt. The heat that causes the melting comes from the surroundings (the warmer cream mixture). By lowering the temperature at which ice is frozen, you were able to create an environment in which the cream mixture could freeze at a temperature below 0 degrees C into ice cream.