Tips & Warnings??? You do not have to add the powdered milk, but it does make a thicker yogurt, which makes it easier to 'fold' fruits and other items into it.??? You can use cow's or goat's milk.??? You can use dried yogurt cultures, but using ready made is so much easier.??? Whole milk makes richer flavored yogurt, skim milk makes it non-fat.??? You can use yogurt instead of sour cream.