Author Topic: fat separation: how to "re-homogenise"?  (Read 1120 times)

Offline tinysar

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fat separation: how to "re-homogenise"?
« on: March 29, 2012, 08:15:27 AM »
Well no, I don't actually want to homogenise my milk.
It's just that I'm using mainly unhomogenised milk at the moment - it's usually a bit old by the time I get my hands on it and has formed quite a definite cream layer (in some it's like a plug of cream blocking the top of the bottle!) - it's Jersey milk too, so there's plenty of fat. I'm used to using goat milk, so this is a new problem for me. I have tried agitating the bottles gently for a few minutes to mix the cream back through, but this doesn't always work if the cream is solid - sometimes it just breaks up the fat into smaller chunks. And even if it does "re-homogenise", it's still separating out again somewhat during the ripening stage. So I end up with little (~2-5mm diameter) globs of butterfat mixed through my curds.

Is there a better way to mix the cream layer back into the milk?

If not, are the butter globs in my curd going to cause problems for my cheeses (eg. go rancid)?

By my rough calculations, skimming off the cream "plugs" will reduce the fat content by about 1% (i.e. from 4.8% to 3.8%), so the milk would still be ok for most cheese types, but I'd like to know whether this is necessary. None of my books mention this problem.


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Offline Tomer1

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Re: fat separation: how to "re-homogenise"?
« Reply #1 on: March 29, 2012, 08:19:52 AM »
I wonder how old the milk is if you get accuall globes and not just a layer of cream (which can be mixed in during renneting)
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Offline DeejayDebi

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Re: fat separation: how to "re-homogenise"?
« Reply #2 on: March 29, 2012, 05:34:37 PM »
warmimg the milk doesn't help?

Offline Boofer

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Re: fat separation: how to "re-homogenise"?
« Reply #3 on: March 29, 2012, 06:16:18 PM »
I have the same situation. The fresher the milk, the less chance it has of adhering to the top of the bottleneck. Before opening the bottle, I shake the heck out of it to try to dislodge the cream from around the neck.

When I pour it into the kettle...yes, there are floating bits of butterfat. I have found that when you raise the temperature of the milk during the "cooking" stage, it melts and becomes more mixable with the rest of the milk.

This probably won't work with lactic cheeses that aren't really heated as much. Lactics that I have done have very visible bits of butterfat laced throughout.

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Offline tinysar

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Re: fat separation: how to "re-homogenise"?
« Reply #4 on: March 29, 2012, 10:28:33 PM »
I did try heating them once - just put the bottles into a warm water bath before shaking them. I'm not sure that it helped - the cream melted, sure, but then it kinda separated out again and formed an "oil slick" when the milk cooled again.

So Boofer, your cheeses with the butterfat bits - did they taste ok? I'm not worried about my cheeses looking pretty, and only mildly concerned about the lack of homogenous texture. I'm just a bit worried that the butter might go rancid during the aging time (this is mainly for blues and Cams).

The only mention I have found of this problem in my reading is a suggestion to "top-stir" when adding cream to milk (as in Stiltons) - can anyone explain the reasoning behind this technique? Isn't that just going to keep the cream layer sitting on the top?


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Offline Boofer

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Re: fat separation: how to "re-homogenise"?
« Reply #5 on: March 30, 2012, 08:24:53 AM »
Yes, I've had quite a few "oil slicks" in my cheesemaking past. Hey, it's part of the milk (unless you use nonfat milk  :o ) and is expected to be in the mix. I don't discern any problems after aging...even two years out. I vacuum-seal most of my cheeses to preserve moisture and prevent rind mold incursions, so that may have something to do with the long-term viability.

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Offline iratherfly

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Re: fat separation: how to "re-homogenise"?
« Reply #6 on: March 30, 2012, 10:47:37 AM »
I get the same problem with some of my milk too and I don't think it's a matter of being fresh at all. I get the milk within 6 hours of milking.  In some cheeses I don't mind bits of butterfat but in others it may go rancid before the surrounding paste. More annoyingly, it turns what should be rich, creamy fatty cheeses into skim cheeses because a lot of it doesn't get into the curd and just floats away.

There are two factors that cause this as far as I know
  • Standardization
    This is a practice that is used by many of the milk farmers. They skim the fat layer from all their milks first right after pasteurization. They preserve all the butterfat in a different tank. Then they pour a fat layer that represents 1%, 2% and about 3.8% for skim, lowfat and whole milk bottling respectively. The remaining butterfat is used for the bottling of cream products in the same manner, or for making butter.  It's a little bit like buying the orange juice marked with "lots of pulp" - the pulp is added from a batch tank of pulp and not from the exact oranges used for bottling that particular jug.
  • Breed
    If it's not standardization, then it could be the breed. We already know that some breeds produces entirely different amounts of fat, proteins, caseins etc. The globule size als differs from breed to breed. I recently began working with milk from Dutch Belted cows. One of their hallmarks is having a tiny fat globule (almost like goats milk which never need homogenizing). It is rather homogenized naturally and the fat never rises to the top like Holstein or Jersey milk.
Another thing to think about it changing fabrication technique to match the milk. For example, in semi-lactic triple cremes, the French often use higher temperature and more rennet so that the curd hardens faster and capture the cream in it before it manages to escape in the whey layer.  To maintain the tangy acidic flavor profile and the proper maturation of the cheese (and to assist in faster coagulation) they simply ripen the milk for 6 hours or so before adding the rennet.

Offline tinysar

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Re: fat separation: how to "re-homogenise"?
« Reply #7 on: March 30, 2012, 08:33:04 PM »
Thanks Boofer, good to know.

iratherfly - thankyou for that detailed answer. So you have had butterfat bits in cheeses going rancid? The technique you describe is certainly something to think about - I have to think about how to apply it to blues. Just another question for you - when you say that they use a higher temperature, is that while adding the rennet?

Offline iratherfly

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Re: fat separation: how to "re-homogenise"?
« Reply #8 on: March 31, 2012, 12:49:24 AM »
I have never had them go rancid on me but they do degrade and break down faster as they are subjected to more lipolysis vs the rest of the paste which is subjected to a balance of lipolysis and preotolysis. I also don't do very long aged cheeses so that may have something to do with it...

The more rennet/higher heat method is used for semi lactic fatty cow's milk cheeses such as St Marcellin, Chaource or Delice de Borgogne. These are made in room temperature milk anyway (68°F-72°F - depends on room temp and season). They raise it to 77°F-78°F instead and they use maybe 25% more rennet, but that means 4 drops per gallon instead of 3. That's enough of a difference to make the change.

Blues are a bit different because they need to be a bit more stiff so you can pierce them. The blue itself plays a big part in degrading fat and proteins which is why they get the spicy flavor and the creamy texture. I say, just try it and see what it does. If you don't like the result, try another batch and this time just skim the fat out before ladling, but first add cream to the milk to make up for the loss fat. Don't throw away those gorgeous lumps of skimmed fat! Use it for frying or to make butter.   

Offline tinysar

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Re: fat separation: how to "re-homogenise"?
« Reply #9 on: March 31, 2012, 01:34:00 AM »
That's a good point - the fat chunks might just get eaten up by the moulds.


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