I have some questions about separating raw milk into skim and cream and using it for cheesemaking. I am lucky that I get raw milk easily and cheaply here, but it is balanced by the fact that anything available in stores is not great, the cream especially is either UHT or, if labeled fresh and refrigerated, seems to have gunk added to it, it acts weird when you use it in cooking. Nothing on the label or manufacturer’s information online what it contains or how it’s made, I’ve looked. The skim milk is UHT, and low -fat/2% milk (they call it “toned” milk here) is a mix of milk and milk powder.
I’ve looked on the forum and found posts which give suggestions for how to skim/make cream from raw. They basically recommend leaving the milk at RT for a certain amount of time (12-24 hours) and skimming the cream off the top when it separates out. However, I am a little worried about a couple of things.
First, as suggested by the posts, I left my raw milk out at RT, about 76-80 degrees, for about 12-14 hours. It separated quite successfully into milk with a thick cream layer on top to scrape off. So far so good. However, the milk tastes a little soured/acidic. Also, I am concerned about using this milk, either in skim or cream form, as it has not been pasteurized. So questions:
(1) I can’t use this raw as I have no idea of the conditions under which the milk is obtained/transported. It is from a milk co-operative which buys from sellers and sells to buyers at the same time. A truck makes rounds with multiple stops twice a day. At each stop the sellers bring their milk jugs, it gets poured into bigger containers on the truck, and the truck guys measure out the required amounts to buyers after that. No sanitizing conditions, even handwashing or gloves during this part, so who knows what the conditions are like where the milk is actually produced. Indian buyers deal with the hygiene issues of this by boiling it to death before using. So questions:
(1) Usually I thermize this milk for cheesemaking (145 degrees for 30 minutes, thanks Andy!). If I thermize this at the outset and then leave it out to separate afterwards, will it effect the process of separating into milk and cream (or anything downstream in the cheesemaking process) negatively? Ie; it seems like thermizing it might somehow homogenize it to some degree so that it will be difficult to get the milk and cream to separate again, or that they might separate again later at some point when they're not supposed to during the make. I don't know if this makes any sense.
(2) Not sure exactly how acidic the skim milk is, the PH meter is on the way but has not arrived. Is the increased acidity from sitting out at RT a problem for making either cheese or mother culture? The seminal MC thread by Sailor recommends using skim for MC. In some ways it seems like the RT resting time might be a good thing for MC, a head start on LAB growth, but don’t know if bad bacteria will get a dangerous boost as well.
ETA: Reread the Sailor thread on MCs and some others and I think I understand that part a little better. Ie; I could use a number of things for the MC culture/innoculant growth matrix, all of which would have to be sterilized, including UHT, raw milk (although that might have to be diluted before adding to the vat because it would be really thick after MCing), skim milk from milk powder, the combo milk/milk powder from the stores. Also that acidity is not really a problem as long as you refrigerate/freeze the MCs when they either curdle or drop to 40-4.2 PH for thermo cultures and 4.2-4.5 for meso ones. Do I have that part more or less right? Ugh. I am not very good at this math/science stuff for an Indian.
Thanks in advance for any guidance.