Homogenized, stabilized…

Reader Cici writes in to ask:

What is homogenization and why must all grocery store milk be homogenized and/or stabilized?

The trouble with cream for big commercial processors is that it separates easily. The fat globules that make up 36 (or more) percent of it tend to become attracted to one another and clump up into…well, you can see the results below. Homogenization — essentially hot, high-pressure spraying that tears large fat globules into teeny tiny pieces and distributes them evenly through the milk — helps to inhibit that natural separation.

However it can’t defeat it entirely. That’s where stabilizers come in. A common one is carrageenan, a natural seaweed extract, the molecules of which get between the fat globules to prevent them from clustering together.

What does all that do to the taste of the cream? It changes it, there’s no question. The simple act of homogenizing cream changes it’s physical characteristics, making it blander than it would otherwise be. The reason again has to do with fat and how it interacts with the tongue (see my posts from two weeks ago for more on that!). Add a stabilizer and you get a little further still from cream as it was on the farm.

But then what are the alternatives? Heavy cream is one of the grocery industry’s most returned items, as the clumps of fat that sometimes plop out of the little cartons are commonly mistaken for signs of spoilage. Imagine the response to an un-homogenized and/or un-stabilized mass-market product. The taste would be truer to the real thing, but the texture would probably cause a panic.

Thanks for the question, Cici!

7 thoughts on “Homogenized, stabilized…”

  1. I think it’s important to note that milk does not require stabilizers because casein (the major protein in milk) is an excellent emulsifying agent. Homogenization (a two step process) is carried out at ~67ºC (not “hot”; but warm enough to destroy the lipase enzyme naturally present in milk — which prevents rancidity). During the first step the milk fat globules (high pressure: 140 bar) increase the number & decrease the diameter of the milk fat globules. But they would like to clump back together. Thus, it’s processed a second time (low pressure: 40 bar) and this breaks up any clusters and allows for the casein proteins to cover the surface of the milk fat globules which naturally stabilize them. Homogenization is not a dangerous process nor is it harmful to the consumer. It is just taking advantage of the chemistry of milk.

    Just thought I would share a bit of my knowledge as I am working on my PhD program in dairy chemistry.

    1. Wonderful, Jessie! Thanks so much for sharing your clear expertise here. Come back and do it any time!


      – Joe

      1. I’m always lurking. I guess I should stop being afraid to post. Love your blog, Joe!

        1. Hi Jessie!

          Isn’t lurking the whole point of the internet? But feel free to jump on in anytime you feel like saying something. The water’s warm here.

          – Joe

  2. Joe,

    Why does freezing heavy cream cause it to separate when thawed? Why do you get what looks like butter curds and whey? Is it that water molecules clump together into larger and larger crystals as it freezes?


  3. I love the fact that this blog has attracted so many food chemists! I also did a research project on microbiota found in raw milk, and I’m an undergrad majoring in biochemistry. Keep up the good work and great discussions. 😀

    1. Me too…I always need somebody with a real clue to keep me honest! I hope you won’t be shy about it yourself! 😉

      – Joe

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