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Soaking liver in milk is said to be a common technique that supposedly helps to remove impurities, softens flavour, and tenderises the liver.

I tried it, and the liver turned out alright, but it got me wondering: how does this work? What's the chemistry behind it? Exactly what's happening between the milk and the liver?

Is it the acid in the milk tenderising the liver? That would mean I could soak liver in a marinade based on lemon juice or vinegar? (It doesn't seem like a terrific idea)

Or is there something else involved? I searched around, but nothing I found seemed terribly exact.

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My knowledge about the phenomenon itself is limited but I did see it mentioned in "Modernist Cuisine" (Nathan Myhrvold, p. 147)

Many recipes for foie gras, liver, sweetbreads, and other offal include a soaking step before cooking. For kidneys, this step serves a very simple purpose: to remove any trace of the animal's bodily fluids. Recipes often call for soaking foie gras, liver, and sweetbreads in milk. It is often said that milk improves the taste, purges blood, lightens the color, or affects some other property of the meat. We were skeptical, so we tried several experiments. With a mild-flavored organ meat like foie gras, we could taste a difference, but, frankly, in our tests, we prefer the taste of water-soaked to milk-soaked foie gras. With stronger-flavored organ meats, there is even less of a difference than with foie gras. So our suggestion is to simply soak the meat in water.

So, there you have it.

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The milk has caeisin wich pulls out blood and impurties as well as some metallic elements. Same stands for tapia as it pulls out some of the muddy and overpowering stony elements. I have put in 12 years in kitchens and have seen milk used in many soaking applications mostly for cleansing methods.

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Milk is very close to neutral pH, hardly worth calling acidic, but it does contain lots of calcium, and is a buffering agent, meaning it will tend to pull strong acids or bases closer to it's own pH.

Any time you soak meat in fluid with different salt content, it is going to cause fluid to flow in and out of the meat, this is the same way brining a turkey makes it more juicy, but the fluids can end up flowing in both directions, diluting whatever water soluble compounds are in the meat.

I'm not so sure that the milk actually neutralizes the liver taste so much as dilutes it, and then you throw the milk, with its portion of the flavor, away. If the milk was neutralizing rather than diluting, I'm sure at least half of the old recipes would tell you to do something useful with that leftover milk, like make a white gravy...

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I have done the milk thing and never noticed any real difference in either the texture or the flavor. Maybe its just me. What I did notice is "how" you cook the liver. A Hot pan so when the liver hits it it shrinks right now. Flip it and cook the other side a short time then out and into an already prepared bacon and onion mix to simmer for awhile followed by beef gravy and serve. Mashed potatoes and a vegetable go great and boy is that ever good. While I was a prisoner (NOT a convict) in a South American lock up my cell mate made this our Sunday night special. The Two cane Kid

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As a child my mother would soak liver in a bowl of milk for a day and a half regularly replacing the milk and washing the liver before cooking it. What I noticed is that the blood from the liver would seep out into the milk and the liver would have absorbed some of the milk. I can't remember what she said about the milk treatment but it had something to do with the acids in the milk detoxifying the organ and helping remove the acidic bitterness of the liver. I think the acids break down the toxins and the absorption of the milk into the organ helps it retain moisture whilst at the same time flushes out the bitter tasting blood with all the toxins.

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My mother said the milk helped neutralize the liver. Blood (liver) being slight basic and milk being being slightly acidic together became neutral.

  • But since it has properties of buffer solution, it can be used to bring pH of other solutions (e.g. that in our stomach) closer to neutral even when strong acids or bases are present. I am curious in this case which is the desired reaction? – Adrian Hum Nov 11 '15 at 22:04
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    Why would we want that? We don't neutralize other meats. I don't know if the assumption that meat and blood have the same pH is true, but if it were, why does it have to be neutralized? – rumtscho Nov 12 '15 at 19:40
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You shouldn't soak a liver in milk as that would make the iron in the liver essentially useless to your body, soak it in water.

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    This doesn't answer the question-- OP is asking how and why it works, not whether they should of shouldn't soak the liver in milk or anything else. Also, why would soaking in milk make iron useless to my body? If I have a glass of milk with my steak that doesn't render my steak nutritionally valueless. – senschen Nov 16 '17 at 12:46
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Milk contains calcium, and that will bind with iron ... and make it less bioavailable possibly. We are warned not to take iron supplements at the same time as dairy products. Also, milk contains sugar - in combination, the binding and sweetening may make the liver more mild-tasting than it would be otherwise. The liver is not the organ that produces urine, those are the kidneys which should be well washed also.

  • I edited out the final line of this as it was a question put where we put answers. It's a good question though - I encourage you to ask it using the Ask Question link at the top of the page. – Jolenealaska Jun 1 '18 at 0:50
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My mother and grandmother soaked liver in milk prior to cooking. When I moved out on my own I ignored that step and stopped eating liver. I can't explain the chemical process but I can say it does work, by soaking the liver (chicken or beef) in milk for an hour or two prior to cooking makes the dish less bitter. I have also learned adding some cream at after cooking the liver and letting that simmer I have a nice thickened sauce. I think, at least most of the time, cooking techniques learned through generations may be the best.

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I could be wrong but my reasoning is that heme iron - the type of iron in chicken liver - is not destroyed by milk. Milk is virtually pH neutral when liver is soaked in it it softens the texture and neutralizes any residual urine. All water does is wet your liver making one use more paper towels to pat the liver down and absorb the excess water.

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    Um, how does it neutralize residual urine and how does it soften the texture if it's pH neutral? – SáT Jan 14 '18 at 22:50
  • Milk is VIRTUALLY... operative word being virtually. – Mims Jan 20 '18 at 13:54
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    The liver in a healthy animal (or even most unhealthy ones) doesn't contain urine. You seem to be confusing it with the kidneys, which do. – Mark May 12 '18 at 20:04
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Reading these explanations, debunkings it seems to me, in large part, and taken as a whole, I'm led wonder if there's another answer entirely.

Calf liver is considered better than more mature beef liver, more tender, milder flavor, etc., and it is lighter in color. What if the milk soaking technique originated as a way to 'improve' the color of the liver? Then as the technique was handed down, it would be a natural process for people to make assumptions as to the reasons the technique was beneficial.

  • Sorry, this is not an answer, just wild speculation. – user34961 Feb 5 '18 at 9:06

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