Low-fat milk comes in two types 2 percent milk and 1 percent milk, meaning that 9they contain 2 percent and 1 percent fat respectively. Nonfat or skim milk must contain less than percent milk fat. Buttermilk used to be the liquid left in the churn after butter was made. Now, it is made commercially, by adding cultures of bacteria to low fat milk. This gives the resulting milk a thick texture and a slightly acidic taste.
Some dairies add bits of butter to their buttermilk to give it that fresh from the churn taste.
In some supermarkets and nearly all health food stores you ll find Sweet Acidophilus milk, which comes in whole, low fat and fat-free. This is milk which has had a friendly little bacteria called Lactobacillus Acidophilus added to it. It looks, smells and tastes like regular milk, but has the added benefit of these bacteria, which help you to digest the milk easier and are just plain good for your tummy. In commercial dairies, they separate the cream by spinning it in a centrifuge. The cream is then pasteurized and graded for sale based on how much milk fat it contains.