Among the most popular posts on Milk Maid Marian are those about permeate, so I thought that, for only the second time, I’d break my “never reblog” rule and highlight this post from science communicator, Heather Bray.

Stuff & Things

Today I butted in on a twitter conversation. [View the story “So what is permeate?” on Storify] The question that caught my eye was this:

What is permeate?

I’ve been following the discussion about permeate and I knew that Lynne Strong from Clover Hill Dairies had recently posted something on the subject.

Now my friends who were having the original discussion are not your average consumers. They are scientists! They felt frustrated that they could not find the answers that they were looking for. They could find out that permeate was a natural by-product of milk processing, but could not find out what it actually was.

So I decided to do some research and find out for myself.

I should add that I find the biochemistry of lactation fascinating and I very nearly did my PhD on it. Lactation defines and unites us as mammals on a…

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8 thoughts on “

  1. Marian, it was this article that really caught my eye:

    “…a watery, greenish waste product…”
    “…a “lemony-green liquid substance; it’s certainly not attractive”…”
    “There are no known health risks associated with adding permeate to milk.”

    I agree with the blogger you have linked to: the dairy people have lost control of the message and what looks to me like an acceptable product to add back into milk has now been demonised. It’s not a rational discussion anymore (especially when shows like ACA start a beat-up) and the only logical move is damage control (ie say your product is permeate free). Sad really.

    Just imagine if yoghurt was called “lumpy, bacterially infected spolied milk” or cream was “a yellowish, byproduct loaded with oleic and palmitic acids”.

    If marketers can call rice gunk ‘milk’ then surely permeate can be resurrected!


  2. We would like to know why permeate is added to the milk, also explain exactly of what it consists of. Having both come off the land it wasn’t used in our milk, why is it now?


    • Thanks Stan and Val,
      Permeate is milk’s lactose, minerals and vitamins. Coming off the land yourselves, you’d appreciate how much milk changes in its composition depending on the time of year. Large processors filter the milk to even it out because most consumers have a preference for a particular type of milk, whether that’s full cream or skim or something in between. In fact, a small Queensland processor had to recall its milk not long ago because people thought it was contaminated – turned out the cows had just been grazing on a different type of pasture!

      After the milk’s been split into different components, they (including permeate) get mixed back together to match the type of dairy food that’s needed. You can read more about it at

      Does that help?


  3. I was shocked this week to have to explain to some dairy farmers I work with that permeate isn’t leftover stuff after cheese is made (like whey), but just the watery result of ultrafiltration when components are picked out of milk to make other products.
    If the farmers don’t get it, because processors & industry leaders haven’t explained it, then what hope do average consumers have?

    And no, I don’t work for a milk processor!


  4. The thing that strikes me with permeate is that if it is high in lactose, soluble proteins and minerals, why isnt it used in (firstly) human emergency food rations, as a concentrate / base ingredient or (secondly) as a stockfeed?

    If the processors wont use permeate, where will it end up? Down the drain?


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