Note from Shannon: Please welcome Rosalyn, CFH Content Development Manager and Cultured Kitchen-Keeper.
I have been making yogurt for many years, and in experimenting with raw goat milk, raw cow milk, and different types of pasteurized cow milk, I’ve noticed quite a difference in the results. As most experienced yogurt chefs are aware, raw milk will produce a much thinner yogurt than pasteurized milk – unless it is heated up (sterilized) first. This is because, unless you heat raw milk, the natural bacteria and enzymes that are present in the raw milk will compete with the yogurt culture. Additionally, heating milk does change the structure of the cell membrane in the milk protein, so that it can clump together better and give you a thicker set in the yogurt. Goat milk also produces a thinner yogurt than cow milk, even if it’s pasteurized. This is because of the difference in the protein cells in goat milk. There’s a certain type of casein (milk protein) in cow milk that is absent from goat milk, and the two milks form curds differently, with the curd of goat milk being an average of half the firmness of the average curd from cow milk. Additionally, the goat milk forms smaller “flakes” (curd clumps) than cow milk does. Both of those things may explain why goat milk is easier for many people to digest than cow milk, and it also explains why goat milk yogurt tends to be kind of runny.
One of the ways you can get a better firmness in yogurt is to add powdered milk. This increases the volume of milk solids, so the resulting yogurt is thicker. A couple of years ago, we discovered a great source of organic dry goat milk from Mt. Capra, and this seemed like a great thing to recommend for thickening goat milk yogurt. When we developed some articles for our website on this, we used some data that had been passed along: do not mix proteins when making yogurt. That is, use dried cow milk to thicken cow milk yogurt, and dried goat milk to thicken goat milk yogurt. Recently a customer queried that information, and we took another look at the situation. We do have recipes for cheese that call for the possibility of mixing milks, but with cheese, the curd is formed by coagulation as well as by fermentation, so it’s a little different. We began to wonder: is it true? Should you not mix milk proteins in yogurt? While I was pondering and researching this, I had the opportunity to spend a little time with Sandor Katz, who knows everything. I put the question to him. He thought about it, and came up with pretty much the same thing I’d been thinking: that the different proteins might produce an unappetizing yogurt, but then again, they might be just fine together! Time for some experiments! Read more in the next installment to see what I discovered!