Behind the ingredient: Kosher salt

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If you cook from American blogs or cookbooks, you may have come across recipes that specify ‘kosher salt’. You might have wondered how this is different from other salt, and what on earth is it that makes it kosher?

What is Kosher Salt?

Kosher salt
Kosher salt

In fact, not all kosher salt *is* kosher; it refers most often to koshering salt, i.e. salt for koshering meat, by drawing out the blood. This means that the critical difference between table salt and kosher salt has nothing to do with Rabbis, and everything to do with the shape of the salt grains.

Kosher salt is usually shaped as square or pyramid shapes, instead of the cube-shaped grains of table salt. This is produced either from evaporation (the same process as most sea salt) or by compressing the salt grains to produce flat flakes.

The biggest reason why American chefs love to use kosher salt is that it is much easier to pick up between your fingers and thus gives you tighter control over your seasoning. It sticks to your fingers less than table salt and is easier to sprinkle by hand into an even layer over meat or vegetables. If you’re dissolving the salt into water to cook vegetables or pasta, it makes no difference what you use – table salt is just as good.

How much salt to use

The other effect of the shape of the flakes is that it takes up much more volume for a given weight.

My measurements (on a scale that only measures to the nearest 2 grams):

You can see that 1 teaspoon of kosher salt weighs about half the amount of a teaspoon of table salt, so if you’re using a recipe that calls for kosher salt, you need to use about half as much table salt to get the same effect.

I was really surprised that the sea salt and table salt were a very similar density. Despite having similar sized flakes, the sea salt and kosher salt pack very differently, because of their different shapes (see below). This explains the problem I had with the Hot Bread Kitchen challah recipe (see here) – I had assumed that the sea salt would be similar enough to kosher salt, but in fact I added about twice as much as I should!

Kosher salt
Diamond Crystal kosher salt
Sea salt
Saxa fine sea salt

Which salt to use when:

Sprinkling over meat or veg before cooking – I would use kosher salt or inexpensive sea salt here – it’s easier to distribute it evenly without oversalting things. For meat, it generally makes sense to salt in advance to help draw out water and concentrate the flavour of the meat. This might mean an hour ahead for a steak, or up to 24 hours in advance for a whole chicken or a joint of meat. It has the added advantage of drying out the surface a little, which will help to give you crispy chicken skin or pork crackling.

Table salt
Table salt

Dissolving in cooking water – use fine table salt for this, something cheap. Once salt is dissolved into water, it doesn’t really matter what shape it was in to start with. Bear in mind that it’s particularly important to season water that is used to cook something like pasta, which will absorb the cooking water. For vegetables, you can often get away with seasoning after they are cooked.

Baking – if you want to mix the salt into the dough or batter, then table salt is probably a good choice – you want something fine that will mix in evenly. If you use sea salt or kosher salt, make sure the flakes are nice and fine before mixing in.

Sprinkling over food – this is where those more expensive salts are worth using. Maldon or Fleur de Sel have big, crunchy flakes that add texture to the surface of a crust of bread, the surface of a steak or the top of a brownie. The contrast between the burst of salt from a big, crunchy flake can be really exciting, but is lost if it’s added too far ahead and just dissolves.

Maldon salt
Maldon salt
Fleur de Sel de Guerande
Fleur de Sel de Guerande

More about Kosher Salt:

Serious Eats – Do I Need to Use Kosher Salt

The Kitchn – Kosher salt – where it comes from and why it’s called kosher

 

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louise-marston

I’m Louise, and I’m a compulsive baker, cookbook hoarder and a bit of a food geek. I learnt to cook at home, and later at Tante Marie’s cooking school in San Francisco. With a science degree and a background in IT analysis, I like to understand why a recipe works, not just how to do it. Why the rules are there and when they can be broken.

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