I have an open carton of buttermilk. I think I first opened it around Christmas. I want to make biscuits, but I can't tell if it has turned. It is from pasteurized milk (I would love to find raw milk, but I've had no luck where I live in Portland, OR) and seems to have an "alive" smell that wasn't there when I first opened it. I assume that since it is a cultured drink, its fine, but the carton says that it is best for five days after opening. Can I still make biscuits?