IT ADDS MOISTURE:It will depend on the type of milk used as to how much moisture it will impart.The amount of fat in the milk will also help add moisture.
PROVIDES TEXTURE:Milk in cake recipes, generally makes the texture lighter and stronger (thanks to the protein and lactic acid). Adding the right amount keeps the cake from being dense.
GIVES IT FLAVOR:Milk adds some flavor, but buttermilk will add even more flavor.Now, to use regular milk in place of buttermilk, you’d need to add an acid, since regular milk isn’t acidic.
KEEPS RATIOS STABLE:Ratios have to be in balance in order to get a cake that’s both moist and not too dense.Milk fulfills the role of the liquid part of the ratio as well as part of the fat ratio.
DO I HAVE TO ADD MILK TO A CAKE?It's generally necessary to add liquid to a cake, unless the recipe says differently.It's always best to add the specific type of milk noted as well.
WHAT HAPPENS IF I DON'T ADD MILK?The cake will turn out dry and possibly dense and/or crumbly. Liquid needs to be added in order to achieve a cake that’s moist with a nice texture.
SHOULD I USE MILK OR WATER IN A CAKE?Use what the recipe calls for, otherwise, milk is usually a better choice over water. Milk contains things that water doesn’t, like sugar and fat, which helps with the taste and texture of cakes.