It seems that salting and soaking liver is insufficient to release the blood sufficiently to make it kosher. It needs to be broiled (or is there some other method that also works?)

What's the science behind this? I would think that the heart which is the main blood-pumping organ, would also need to be broiled, but, I guess not. What's special about the liver? Is it the same with all kosher animals and birds?

  • Do you have a scientific explanation for any of the blood rules? None of it makes sense. Why should we suddenly expect this to make sense?
    – Double AA
    Aug 6, 2019 at 15:43

1 Answer 1


The halachic issue behind broiling liver is the prohibition to eat blood (Vayikra 17:10). "Since the liver contains much blood, it therefore not permissible to cook it even after salting it" (quote from SA YD 73:1, see also here).

Maybe less well known is the fact that the heart also cannot be eaten after only being salted and cooked. Blood first needs to be removed from the heart by tearing it open, washing and salting it.

HalachaYomit brings the following

Heart is sold in stores without being koshered first and there is still blood in it and it may therefore not be consumed until it undergoes a halachically valid koshering process. The reason why heart is not salted before it is sold is because when the animal or bird is slaughtered, a large amount of blood is collected in the heart and it is like a container for this blood and it cannot be expelled through salting alone. Thus, even if they would salt the heart, this would not be sufficient to release the blood contained in it and consumption of the heart would still be absolutely forbidden.

Before the heart is salted, it must be torn open and the blood inside it must be washed off with water and only then may it be salted. Tearing the heart refers to cutting it at least once deep enough that it reaches all of the corridors of the heart along either its entire length or width. [...]

After doing so, one should salt the heart well by covering it with fine cooking salt on all sides and leave it in this matter for approximately an hour on top of a rack or other perforated utensil so that all the blood can drip out of it.

If one does not wish to salt the heart (or any other piece of meat for that matter), one may kosher it by grilling it (preferably, one should place a small amount of salt on the meat and only then grill it) since grilling also causes the blood to flow out of it and it will then be permissible for consumption. Even when wishes to kosher the heart by grilling it, one must tear it properly as we have explained above regarding salting the heart.

So it is really the presence of blood in blood-rich organs, such as the liver and the heart, which is the root issue.

There remains a key difference between the liver and the heart. One can take blood out of the heart by tearing, rinsing, salting then cooking it (see here). For the liver, one needs to tear or slice, rinse then broil/gril it (see here and there).

I imagine the difference is that blood gets more absorbed into the liver than the heart. @JoshK in comments speculates it is because of the density of the liver. But I don't feel qualified to comment on the science of it (and am not sure it belongs on this site).

  • Then I don't see how this answers the question at all. "What's the science behind this? I would think that the heart which is the main blood-pumping organ, would also need to be broiled, but, I guess not. What's special about the liver? Is it the same with all kosher animals and birds?" He's right that heart doesn't need to be broiled, still doesn't know why, and doesn't know if this applies to all animals.
    – Double AA
    Aug 6, 2019 at 16:39
  • Just observation rather than sourced, liver is MUCH denser than beef heart. It may very well be possible to get the blood out of a beef heart by salting and soaking once properly scored to allow for drainage; this would not be the case with liver. Also practically speaking the only way beef heart has an appetizing texture and flavor is if it is well marinated and then grilled. Stewed or deep fried it would be rubbery. Aug 6, 2019 at 16:41
  • @DoubleAA you have a point and I edited further. I try to look at the halachic aspects since I do not believe the science of the differences belongs on this site. This is as far as I am able to go
    – mbloch
    Aug 6, 2019 at 18:38
  • 1
    If the halacha is based on the science, why wouldn't that belong on this site?
    – Loewian
    Aug 7, 2019 at 0:49
  • 1
    I think this post provides information that gets the reader closer to knowing the answer to the question by a) correcting the question's assumption that hearts just take simple salting, and b) speculating as to a possible reason livers require roasting, in contrast to hearts.
    – Isaac Moses
    Mar 18, 2022 at 19:38

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