Many baking recipes call for milk as one of the main ingredients. Many recipes will call for a specific type of milk – whole milk, low fat, skim – and others will simply call for it without specifying the fat content. This brings a couple of questions to the surface: what is the difference between whole milk and skim milk, and does it matter what you use when it comes to baking?
The difference between whole and skim milk is the fat content. Whole milk generally contains about 3.5% fat, while skim contains none. All liquids in baked goods help to bind things together – even if you add water to a recipe – but fat plays an even more important roll and acts as a tenderizer and moisturizer. This means that cakes and muffins with slightly more fat in them tend to have a finer crumb and not be quite as dry when they have a little more fat in them. In professional bakeries, whole milk is the standard for baked goods and most recipes for home bakers – unless otherwise specified – tend to assume that you will be using whole milk. You can substitute low fat or skim milk in just about any recipe that calls for milk, but because the recipe was probably designed to work with a little more fat in it, you should mix carefully so that your product doesn’t become tough from overmixing.
I typically use low fat milk when I bake because that is what I keep in my kitchen on a regular basis. I tend to note in recipes when I think using a different type of milk will be beneficial. I prefer to use whole milk in ice creams and custards when possible because that small amount of extra fat in the milk contributes to a much richer mouthfeel in the end. In cakes, muffins and other baked goods, you should have results that are very, very similar regardless of what type of milk you use.