I'm trying to turn whole milk/yogurt into skimmed/no fat milk/yogurt. I don't live in US and no fat dairy products are 4-5 times expensive also hard to find in store. Can I just whip pasteurized homogenized milk or yogurt and make butter.
If I take butter from milk remaining liquid is buttermilk, can I use this for sour cream, is this cultured buttermilk. Of course I can't find buttermilk either.
Best Answer
There are many questions here, but the practical answer to almost all of them is "no".
To understand why, you have to understand what all these products are.
What won't work
If you were to churn butter from raw full fat milk, you would end up with butter + buttermilk (old meaning). The result is not low-fat or skim milk, since it is not an emulsion. It is also not the buttermilk required by modern recipes. You could it for either antique recipes or drink it, but it isn't like milk.
If you try to churn store-bought full fat milk, nothing will happen, because the emulsion is stabilized.
If you try to churn yogurt, nothing will happen - Getting butter from yogurt.
What works in principle
If you want low-fat buttermilk (modern meaning), the only way is to start wih low-fat milk and culture it. The catch: you said you don't have low-fat milk.
Also, if you want your own low-fat milk, the way to go is to find some raw milk, pasteurize it yourself, then let it sit in the fridge for 2-3 days. Then remove the fat from the top. You cannot control the exact percentage of remaining fat that way, but is definitely lower than in raw milk. It is certanly not no-fat, probably closer to the 1.5%ish milk that is sold in many countries. The catch: depending on your location, it may be easier to buy 1.5% milk than to buy raw milk.