A sample of the milk is taken and tested for its milk fat content, flavour, odour, and bacterial count. Milk naturally contains bacteria and because milk is so nutritious, bacteria can grow really well in it. This process is named after a famous French scientist, Louis Pasteur, who discovered that heating milk quickly and then cooling it quickly kills harmful bacteria without changing the milk's nutrient value. Therefore, the milk can be stored unopened, at room temperature for up to 6 months. Once opened, it too needs to be kept in the refrigerator.
Milk fat is what makes milk creamy, rich and flavourful.
A homogenizer is a machine which forces the milk at high pressure through tiny holes. This process breaks up the milk fat globules into particles one eighth their original size. When the milk fat particles are that tiny, they stay evenly suspended. A very special nutrient, vitamin D , is added to milk because we need it, along with calcium, to grow strong, healthy bones and teeth. When we add nutrients to food, we say that food has been enriched or fortified .