Question about milk and milk powder
I'm planning to make txfarmer's recipe of Sourdough Sandwich Bread back from 2010 but I don't plan to by a whole package of milk powder and would rather replace it with UHT milk I already have on hand; I'm wondering how much should I use and how much water I'd have to cut out? From Google, milk is 87% water on average, so I assume that would determine the amount of water to be cut out, but should I base the amount of milk to use on total milk solid (avg. 13%) or should I deduct fat (avg 4%) from that also (so, 9%). Say I'd need 10g milk powder for my batch, do I use 77g or 111g of milk?
Another question, yesterday I made pancake and I put starter into it. What caught my attention were white lumps which started to foam up on top when milk was added into the mixture of butter, sugar, egg, and starter. At first I thought it might be the grains of butter clumping up some how, but when I came back to think of it, I suspected they might be milk protein clumping up because of acidic starter? In the end, my pancake turned out fine after it was mixed with flour, but I was a bit concerned if it would be okay if it was a bread dough? I normally mix starter with liquid to break apart and disperse the starter before mixing with flour and (sort of) autolyse so I'm a bit concerned if milk would clump up in that process and if clumped up milk would make the dough lumpy? I've never use milk in sourdough before.