Kashering Liver

Blood is prohibited, and meat is ordinarily rid of it by salting. Liver is the exception. It holds so much blood that salting cannot draw it out, so liver is kashered by broiling over a fire — the heat drives the blood out directly.

This is one of the few kashrus procedures a household might perform itself, and the details matter.

Before you start: timing

The clock is the part people miss.

• Pour off collected blood immediately. Liver should not sit in blood for twenty-four hours, so empty the bag or container as soon as it arrives.
• Frozen liver must not defrost sitting in its own blood for more than twenty-four hours.
• Thaw completely before broiling begins.
• Kasher within seventy-two hours of defrosting.

Preparing the liver

Beef or calf liver. Remove the fats. Then make deep crisscross cuts, horizontally and vertically — or slice the liver instead. The cuts open channels for the blood to leave. Wash the knife in cold water after cutting raw liver.

Chicken liver. No cutting needed, but make sure the gall bladder has been removed.

Wash the liver after cutting.

Salting and broiling

Salt lightly on both sides — enough salt to give it a good taste, no more. Salt immediately before broiling, because the salt draws out blood and the liver should not then sit in it.

For the broiling itself:

• Use a separate grill or dedicated appliance. A dedicated toaster-type device is one common arrangement.
• Make sure the catch basin collecting the blood is not too close to the liver, so the blood does not come back into contact with it.
• Livers may touch one another and may lie stacked. With beef or calf liver, the cut side should face down.
• If the heat comes only from below, turn the liver — using a utensil designated for this, not a kosher one.
• The liver must be at least two-thirds fully broiled to be considered kashered.

Afterwards

Remove with a fork kept exclusively for this, not a kosher one. Then rinse three times in cold water, after which the liver may be sautéed or cooked normally.

One timing rule applies at the end as well: if three days passed between defrosting and kashering, the liver may be eaten in its broiled state only, and should not be cooked further.

Why broiling works, and what breaks it

Broiling draws blood out more powerfully than salting does. But it only works on a piece lying open to the air, over the fire, with no sauce and no liquid — or over glowing coals.

Two worries that sound serious turn out not to be, and it is worth knowing why:

• Will it reabsorb the blood it is releasing? No — while a piece is releasing, it does not absorb.
• Will it absorb back from the spit or the grate? No — whatever it takes in, it immediately gives back out.

What does break it is anything that blocks the blood's exit. So broiling may not be done in a pot, a pan, a tray, or on any surface. The piece must be exposed to the fire on every side — laid on a grate, or skewered on a spit, or anything else that does not impede the blood leaving and being burnt.

Wrapping, coating and brushing

All of these fail for the same reason, and one of them is counter-intuitive:

Oven floor and hot plate

Two alternatives to an open flame, both permitted by some.

The floor of a hot oven. A swept oven whose floor is very hot: some permit broiling meat or liver directly on it even with no actual flame, since the heat of the floor can draw out and consume the blood. Others are stringent.

An electric hot plate. Some permit it where the plate has no rim, so the blood runs off or divides and drains — or is burnt off by heat above 100°C. Two conditions attach: put the liver on only after the plate is thoroughly heated, and the heat should be such that a cloth laid on it would burn. One authority forbids it where the plate does not stand at a slope, since then the blood has nowhere to go.

The common thread is the same as above: the blood must have an exit.

Salt, and the sick person

Before broiling, keep the meat or liver away from salt.

Where the custom is to salt the liver lightly as it goes on the grate — and many do — the timing is strict: salt it only as you place it on the fire. If it was salted first, it must go straight onto the fire and not be left standing, and it must not be put down salted on a plate, pan or tray, even briefly.

For a sick person who may not eat salt, one may be lenient and not salt the liver at all while broiling it. And bedieved, liver that was neither rinsed nor salted before broiling is permitted.

Rinsing, before and after

Before: rinse off any congealed blood on the surface. There is no need to soak it, and where it is already clean, no rinsing is needed at all. If you did rinse it, do not put it on the fire dripping — wait for the water to run off first.

After: practice divides. Some rinse the liver after broiling even when eating it broiled; Sephardi custom did not. In many Ashkenazi communities the custom is to rinse the liver or meat three times, to remove any blood still clinging to it.

Turning it, and how long

The older guidance is not to roll the spit continuously — leave it until the blood has flowed from one side, then turn it so the other side broils. Bedieved, turning it is fine; turning it slowly is fine. And some permit turning the spit freely even lechatchila, which is the widespread custom.

How much broiling is enough? Lechatchila, until it is fit to be eaten as broiled. The practical test given: if it has dried and hardened on the outside and nothing drips from it, that is the sign it broiled properly and its blood has run out.

Bedieved, half-broiled may be eaten as it is. And while it is still short of half-broiled, take care not to lift it off the fire — even to adjust the flame.

If you want to cook or fry it afterwards

Then it must be broiled fully first. Half-broiling is not enough.

The Taz records the practical form this took: because people were not reliably expert at judging it, the custom became to broil until the outside has dried, and only then cook — and that is what one should do. For a sick person one may be lenient with half-broiling even where it will be cooked afterwards.

Where the liver was salted, rinse the salt off before and after broiling and then cook, because the salt absorbed blood. Bedieved, where it was not rinsed and was cooked that way, it is permitted — the blood was burnt, and there is presumably sixty in the dish against it.

Some are lenient specifically with liver, holding that half-broiling suffices even before cooking, since liver is softer than meat and the fire extracts its blood more readily. Even so, lechatchila liver too is broiled fully where it will be cooked.

The blood that drips

This is the part that affects your kitchen rather than the liver.

Blood and juice dripping off during broiling — before the piece is half-broiled — is forbidden, and forbids whatever it lands on, vessel or food. A vessel it lands in needs hagalah.

So when broiling in a kosher oven or over a kosher hob, take care that blood does not spatter. The recommendation given is to line the hob or oven with silver foil before broiling.

There is a disagreement about a tempting alternative. Some suggest a tray of water in the oven beneath the grate — not touching it — so dripping blood lands in water and is nullified rather than forbidding the oven. Others object that the water boils and steams, the meat then does not broil properly in the fire's heat, and it may end up cooked by the steam — which would forbid it as meat cooked without salting. A remedy that creates a worse problem than the one it solves.

Where blood from one piece drips onto another that is already broiling, the fire does not burn it off — it drives it into the meat. The Beis Yosef holds the receiving meat is forbidden k'dei netilah: peel off a layer thick enough to lift away, discard it, and the rest is permitted. The Rema requires sixty against the blood that fell; without sixty, all of it is forbidden.

Never liver and meat together

Do not broil liver and meat at the same time. Liver releases far more blood than meat does, and it may drip onto meat that has already finished releasing its own — at which point the meat will absorb it. Bedieved, where they were broiled together, it is permitted.

The same applies to one spit, even with the liver below and the meat above. The reason is pleasingly practical: spits get lifted and turned, the top becomes the bottom, and now the liver is dripping onto the meat after all. Bedieved the meat is not forbidden.

Some permit self-rotating spits even lechatchila, since these stay level along their length; others are stringent even then.

The utensils stay separate

This is the part most often underestimated. Everything used in the process — catch pans, forks, grates, the appliance itself — is treated as non-kosher and kept exclusively for kashering liver.

They may not be washed together with other utensils, and may not be washed in the sink where kosher utensils are washed.

That is a permanent arrangement, not a one-off precaution, and it is worth knowing before you start rather than discovering afterwards.

If any of this is unclear for your situation, ask your rav — and if you are buying liver that has already been kashered, this is what was done to it.