Buttermilk has been a staple in the home and around the world for thousands of years. People have used it for cooking and baking and as a beverage, but it has also been touted as a skin refresher, a soap ingredient, and an animal feed. When it comes to creating alternatives for buttermilk you have to consider two issues. One is what buttermilk actually is. The other is what you want to use the buttermilk for. Buttermilk used to be the liquid that was left after you finished making butter. That could have two forms, sweet or sour, because some people made butter from sweet cream, others from slightly soured cream. These days, buttermilk is a cultured product, just like sour cream and yoghurt. It bears little resemblance to the original buttermilk our ancestors used. The good part of that is that today's buttermilk is a very standardised product. This means that you have a definite goal when you look for a substitute. Here are some of the alternatives you can use.
Use buttermilk powder in a baked recipe. This is the easiest. Just follow the directions on the package to use buttermilk powder. Buttermilk powder can be found in most grocery stores, in the baking section with the flour and sugar.
Use mayonnaise, whipped salad dressing, or sour cream as a substitute for buttermilk in things like sauces and salad dressings. You might want to add a small amount of lemon juice to get the characteristic tangy flavour. This will only work if you are not heating your dish. It's a great alternative in things like ranch dressing.
Use one of several alternatives in yeasted baked goods, like rolls. These recipes are using the buttermilk for flavour. Use milk, cream, half and half, or sour cream, the same amount called for in your recipe. For every cup, add one teaspoon of lemon juice. Stir them together and let the mixture sit for 15 to 20 minutes.
Use the same substitution method as in Step 3 when you are making quick breads and other things that use the buttermilk as part of the leavening process. Things like pancakes and other kitchen staples using buttermilk are using the sour component of the buttermilk as part of the ingredients to make the dish rise. Again, use milk or cream cup for cup as called for in the recipe, but add one teaspoon of vinegar to the milk and allow it to sit for 15 to 20 minutes. Vinegar is better in this case because it is more consistently sour than lemon juice.
Use these methods to eliminate dairy from a recipe. Use soy milk, coconut milk or cream, almond milk, rice milk, or another substitute in the same way you would use regular milk or cream in the previous steps. Add the same one teaspoon of vinegar or lemon juice per cup. Use vinegar or lemon juice depending on whether you are using it for flavour or as a part of the leavening.
Use vanilla flavoured soy milk to add an extra flavour dimension to your recipe. Cultured buttermilk has a thick consistency, so don't hesitate to use cream or half and half for your alternative. Sour cream can be used as an alternative in baked goods as well. You may have to add a bit of lemon juice for acid.
Remember that vinegar has a consistent acidic percentage but lemon juice varies.