Making skim milk and cream from raw and using for cheesemaking

[not_ally]

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.

[Bantams]

You can either separate the cream by using a centrifugal cream separator, or by allowing the milk to settle for several days and then ladling the cream off. The milk needs to remain in the fridge.
When hand-skimming, the less agitation the milk goes through, the better.  Ideally the still-warm milk will go into a fairly wide vessel in the fridge (more surface area makes for thicker cream and easier skimming), chills and settles for 2-3 days, and then is skimmed.
Stirring, pasteurizing, or other disruptions to the milk before settling make the cream slow/difficult to rise.  If left at room temp the milk would sour (which also impedes the cream rising).

What do you need skim milk/cream for? Most cheeses can be made with whole milk, although I do wonder what butterfat/protein values your milk source has as the Bos Indicus breeds have very rich milk. If the butterfat % is quite a bit higher than the protein % (say, 8% bf and 4% protein) then taking a little cream off will be helpful for your longer aged cheeses.  Our herd tests at about 4.5-5.5% bf and 4.2% protein and I make all our aged cheeses with whole milk, no problem.

For a mother culture I would just use store skim because it is a blank slate. 

One issue with hand skimmed milk is that the slow chilling and long settling time are not conducive to good cheese milk - too much LAB growth. It's ideal for making cultured butter and clabber/farmers cheese/etc but not so much for other cheeses. This is especially true if the milk is kept warm for a while or the containers aren't sanitized.
Alpine cheeses that are skimmed call for the evening milk to settle overnight in a shallow pan - in a very cool room (50°F?) - and then get skimmed before the morning milk is added. You can do this short duration cream rising if you only need to take off a bit of cream, as most of the cream will still be in the milk portion.  Letting the fresh milk settle for just 12 hours (vs 2-3 days) shouldn't cause issues with cheesemaking unless the milk already has a high bacterial load - which it sounds like your milk source does. I think your best bet would be to pasteurize the raw milk (145/30 minutes) and use it whole. 

[not_ally]

Bantams, thanks for taking the time to read through all that and answer so cogently and comprehensively.  I'm glad you were able to get through it, I think I was more confused after I wrote it than when I started.

Ok, it looks like trying to separate the milk is just not a good idea.  A lot of effort for something that is not likely to work well.  I wanted to be able to do it because I am sure I found a recipe here that stressed using at least some percentage of skim milk (can't find it now, I have dozens of forum "share this link" emails that I have to go through and organize).  I think it must have been some sort of Alpine, probably jarlsberg. 

But the bigger issue is the cream that is marketed as fresh heavy cream here.  For ingredients it states only "Medium Fat Cream containing Milk Fat 40% minimum" but I think there must be some form of gum or other stabilizer/thickener in it. It doesn't whip well, when used with coffee it leaves little chunks and a greasy, oily film on the surface.  When I recently used some of it in a recipe for boursin it did liquefy but didn't seem to mix well with the milk and ran out with the whey while draining in the molds.

There are some recipes that call for adding cream that I would really like to make, including some cams/cambozolas/blues.  If they were long aging cheeses I'd just take my chances with not pasteurizing and using raw milk and the cream thereof, but don't want to risk it with these since they are right at the two month aging mark.  So I am just going to try the store version of heavy cream and/or UHT cream, and see how it goes.

Will use the store milk for MC.  Do you think it is better to use the UHT (skim) or the 2% (refrigerated mix of milk and milk powder? 

Thanks again.   

   

[Bantams]

I think I would use the 2% store milk for the cultures. It's the same here - all skim milk contains some powdered milk.

I think your store cream is pasteurized but not homogenized (does it say?) That's the usual appearance - kind of clumpy on top with some butterfat globules (happens just from the agitation of the bulk tank paddle, transferring milk, etc). When warmed you'll find spots of melted butterfat and an oily sheen on top. And that's why large producers homogenize.
You can try warming the cream first in your pot to 100+°F (stirring well to get all the lumps out), then add the cold milk and bring up to your culturing temp. Should be able to melt the lumps that way.

[not_ally]

That's the frustrating thing, the "medium fat cream containing milk fat 40% minimum" is the sum total of the ingredients disclosure. Very different labeling requirements here.

I'll do what you recommended on warming the cream. I miss the ease of, well, everything in the US. Thanks, Bantams.