Cooking with Liquid Nitrogen

[tan319]

Can you list some of the safety precautions?

Thanks!

[slkinsey]

we also are doing cocktails spheres that are liquid in the center and frozen on the outside........

This sounds very interesting. Can you explain how you do it?

[nathanm]

There are several web sites that have full safety info, such as this

The following is provided for information only, use at your own risk.

The basic things are this:

- Get a pair of Tempshield cryo gloves - these are available from scientific supply places like Fisher Scientific and others. You want the waterproof model (there are also non-waterproof), and I like the elbow length ones.

- Get a cryo apron, also by Tempshield

- Get safety glasses, or a face shield. I use a full face shield that I happened to have already from using oven cleaner. Here is a similar one that from Amazon

The gloves and apron are ridulously expensive - like $150 each. I know people who use much cheaper gloves, or no gloves, but these are the correct ones to have.

LN2 is VERY cold. If it splashes on your skin it could really hurt you - or not. Surprisingly, if it falls onto a a convex surface (i.e. the back of your hand) it just falls off. You hand is so hot compared to the LN2 that it boils at the bottom and a cushion of nitrogen gas lets it fall off harmlessly. In graduate school (I was in physics) we would sometimes play irresponsibly with the stuff and have hallway fights with it ect. I've had it on my skin many times without a problem - even had it run down my back under my shirt.

If you pour a bit onto a flat surface - a plate, or pan - droplets will float and dance on teh surface until gone, just like drops of water will do in a very hot saute pan, and for the same reason.

BUT that's only if there is a way for it fall off. If it falls onto a concave surface where it will collect instead of fall off, such as the palm of your hand, well that is BAD.

Your biggest risk is having it splatter into your eyes - hence the shield or goggles. Any saftey goggles should do, but I like the face shield because it does not fog up.

The other risk is soaking into clothing - that is BAD. There are plenty of lab rats who work with the stuff that will tell you that the best way to handle LN2 is naked.

An example of a really bad thing to do is to spill some so it goes in your shoes. You'll lose a bunch of flesh that way.

So, I use cryo gloves and cryo apron. However, if I didn't have those I would use waterproof gloves and a waterproof apron, and maybe rubber boots.

The other main hazard is that when LN2 goes from liquid to gas, the volume increases. So, you NEVER seal it in a container. A popular stunt for physics grad students is to pour a bit into an empty 2 liter plastic soda bottle, then throw the bottle into a plastic trash can half filled with water, or into a swimming pool. The whole thing will explode. I don't mean a little explosion either.

So, NEVER seal it in a container. Never pour it down a drain - it will freeze the water in the sink trap, and can make it explode.

This all sounds bad, but I do not believe that LN2 is any more dangerous that fry oil. You wouldn't want to fill your shoe with hot fry oil either. In fact, it is probably more dangerous spilling hot oil on your hand than LN2.

I use the gloves and apron for pouring between the storage dewar (container you store it in) and the container that I use to dunk food in -(a open mouth dewar, or small plastic cooler). However, once I am using it I usually have at least one glove off. because they are just too cumbersome.

In practice you use the same sort of tools you'd use for frying in oil - i.e. tongs and mesh strainers to catch the food and bring it out. For some purposes, like making a powder by spraying a liquid into LN2 a fine mesh chinois is best.

[nathanm]

Chef Sean can reply on how he makes his cocktail spheres - I am curious too.

Here is a trick that may be similar. Take a mixture which normally does not freeze at typical freezer temperatures - for example something with lots of sugar in it (syrup), or lots of alcohol in it, or an oil that does not typically freeze.

You can use LN2 to freeze these things. Even pure vodka will freeze. Alcohol freezes at -117C, but LN2 is at -196C.

Once you've frozen the normally unfreezable liquid you can encase it in something else around it - say ice cream, mousse.... or a liquid which will stay frozen at normal freezer temperatures. Then you put the whole thing in the freezer and let it sit a while - usually overnight. Ironically the goal of putting it in the freezer is to WARM UP the core that was frozen with LN2, which then melts into a liquid. Obviously, the encasing should not leak.

Heston Blumenthal makes a mock egg this way that has a liquid yolk. The mock yolk has enough sugar and alcohol that will be liquid in a normal freezer. He freezes the mock yolk, then makes the mock egg white and molds it around the yolk and lets it stay in the freezer.

When the customer's spoon goes in, they find a liquid yolk.

This is a variation on things like Chinese soup dumplings where you freeze a liquid, encase it in something, then heat the something and serve with liquid inside.

You could do this with LN2 also. If you wanted vodka filled dumplings or syup filled dumplings you could freeze the vodka with LN2, encase in dumpling dough, then cook the dumplings. The only issue here is that your dumpling dough must be watertight.

[slkinsey]

My father used to regularly win bets from his colleagues at MIT by gargling liquid nitrogen. I'm not sure what the trick was, but he never burned himself. I'll have to ask him about it.

[Shalmanese]

The other risk is soaking into clothing - that is BAD.  There are plenty of lab rats who work with the stuff that will tell you that the best way to handle LN2 is naked. 

An example of a really bad thing to do is to spill some so it goes in your shoes.  You'll lose a bunch of flesh that way.

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Naked and shaved preferably. Hair + LN2 = BAD too.

[Patrick S]

My father used to regularly win bets from his colleagues at MIT by gargling liquid nitrogen.  I'm not sure what the trick was, but he never burned himself.  I'll have to ask him about it.

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Interesting. There is a picture of a girl doing this here. I think I'd pass on that one!

[Patrick S]

The other risk is soaking into clothing - that is BAD.  There are plenty of lab rats who work with the stuff that will tell you that the best way to handle LN2 is naked. 

An example of a really bad thing to do is to spill some so it goes in your shoes.  You'll lose a bunch of flesh that way.

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Naked and shaved preferably. Hair + LN2 = BAD too.

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And besides, what could possibly be more sexy than a bunch of naked and shaved lab rats exploring the mysterious ways of LN2? Add some MDMA, loud techno music, and flashing lights, and you have yourself a fine rave . . .

[nathanm]

My father used to regularly win bets from his colleagues at MIT by gargling liquid nitrogen.  I'm not sure what the trick was, but he never burned himself.  I'll have to ask him about it.

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Yes, amoung irresponsible things that science types do with LN2, this is one of them.

I have not done it myself - I'm crazy, but not that crazy. I am sure it can be done, but it would seem that if it isn't done just right you'd have a real problem.

[Wendy DeBord]

Is there any chance someone would do a demo on this? I think we'd all be thrilled to see someone working with it.

Please, please, please, etc..........

[edsel]

Wendy, I hope you're not asking for a demo of the naked-and-shaved nitro treatment.

Louisa Chu has an account of Albert Adrià's oil-encapslated-in-sugar thang here. I'm wondering how he gets the oil encapsulated in the sugar coating - does he super-freeze it wit LNG? Enquiring minds want to know.

[nathanm]

No, I believe that what he does is siply pour the oil into a blown sugar bubble.

You could freeze things and then coat them this way I suppose. Albert Adria does lots of other things with liquid nitrogen.

[heidihi]

I was at a party the other night where someone brought a large tank of LN2 to make ice cream.

Some shots of the process, and detail shots of the consistency below. It was wonderfully smooth - soft-serve style ice cream meant to be consumed immediately.

Mid-mix

Ready to eat

-h

Edited December 29, 2005 by heidihi (log)

[_john]

I have let a thin stream of honey fall in to a styrofoam cooler full of liquid nitrogen to make "honey shards." They are very good on their own, but their main purpose is a garnish for ice cream. maple syrup and black strap molasses are also amazing. very thinly sliced fruits and vegetables can be made to mimic crunchy fried items as garnish for desserts. I have also experimented with shattering thin items to create shapes that are impossible to make with a knife. There was an experimental steak tartare made in this way.

very high temperatures can do amazing things as well. I read about a chef using lasers to cook bread from the inside out etc. can't find the article however.

[nathanm]

Great pictures!

[jsolomon]

I'm having horrid little visions of someone balling up mashed potatoes and dropping it into LN2 with gravy so the outside is frozen and the inside is still hot and serving them to unsuspecting folks as a tapas item.

Right next to the glowing pickle ornament at the bar.

The Glowing Pickle Page

Edit to add: For LN2 Ice cream, the recipes I saw on the web vacillated between equal amounts of mix and LN2 to 5 parts LN2 to 1 part ice cream mix. Most recipes called for 1 part mix, 2 parts LN2. I vaguely remember Dr. Carr making it with 2 parts mix and 1 part LN2.

So, obviously, YMMV. But, I have to ask, after 10 years of lab-ratdom, are there that many lab-rats that you want to see naked, and shaved? I shudder at the thought of most of the ones I know.

Edited December 29, 2005 by jsolomon (log)

[heidihi]

Thanks Nathan,

_john - I you come across that article again, I would love to read it - please post.

With the batch of LN2 ice cream I observed, we started with about 4 cups of a pretty standard vanilla base in the the metal mixer bowl. Turned on the mixer, and started adding the LN2 gradually - a bit at a time over the course of about four minutes. Everything quickly firmed and fluffed up, the room we were in looked like a haunted house.

With the leftover LN2 they went out back with the Kitchen Aid mixing bowl a hammer, and a selection of things they were interested in freezing and then smashing.

- a whole onion (more impressive in theory - the core didn't seem to get cold enough, and it didn't really shatter the way I imagined it would)

- leafy herbs (kind of interesting - they ended up very dry, brittle, and flaky)

- a cigarette (similar to what happened to the herbs - the wrap around the tabacco got dry and brittle)

-h

[Wendy DeBord]

I recieved the lastest issue of Pastry Art & Design (Decemeber 2005) yesterday and the whole issue is devoted to frozen desserts. Toward the back of the magazine Tish Boyle did a "how to" with Robert Ellinger on 'liquid nitrogen dip' and 'instant ice cream' as shown above in Heidihi's post.

[Shalmanese]

- a whole onion (more impressive in theory - the core didn't seem to get cold enough, and it didn't really shatter the way I imagined it would)

- leafy herbs (kind of interesting - they ended up very dry, brittle, and flaky)

- a cigarette (similar to what happened to the herbs - the wrap around the tabacco got dry and brittle)

-h

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Heh, it's funner to dip a cigarette in liquid oxygen and then hand it to an unsuspecting person. When they try and light it, it turns into a massive fireball which, fortunely, isn't hot enough to hurt anything.

[annecros]

Can you huff it?

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Yes.

But then your face would fall off, when it thaws.

[tan319]

A scientist who's little girl goes to school with my daughter was telling me about an accident with a bunch of NASA scientists who were wiped out by the odorless vapors in a improperly ventilated room.

I guess maybe not as much of a chance of that happening in a pro kitchen with hoods but...

[BryanZ]

But where can home cooks get liquid nitrogen? Give me a source and I'll get some.

[Shalmanese]

But where can home cooks get liquid nitrogen?  Give me a source and I'll get some.

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Scientific and Medical supply stores. Although some are a bit more picky about who can buy. If your near a university (which, IIRC, you are), you can sometimes just rock up to the chemisty department with a thermos and they'll fill it for you then and there.

Be careful though, it's not especially dangerous but there are some precautions you have to take.

[slkinsey]

My father used to win bets around MIT by gargling liquid nitrogen. Just like dipping your hands into a pot of boiling water, I imagine there are ways to dip one's hands into liquid nitrogen without being burned. Still, though, I wouldn't recommend it. Liquid nitrogen is still something that can hurt you quite badly if you're cavalier about the way you use it. I'd much rather be hit in the eye with a splashed droplet of boiling water than a splashed droplet of liquid nitrogen.

[inventolux]

Not really dangerous at all

really, so how come all the pro's insist you use it in the books, Dani Garcia, El Bulli, both my meals at morimoto ny and fat ducky ?????

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The only "pros" with LN2 I know are the ones that work for the LN2 companies. I go through 1,000 litres of LN2 every week. Thats enough to be considered a pro, but I am far from a pro when it comes to the knowlegde the scientists have. I can tell you LN2 is no more hazardous that working with gas burners. One just has to be careful to have adequete hvac and dont keep your hands in the thick fog or liquid for too long. The rules of engagement are similar to a gas flame. If anything, gas is MORE dangerous because it can blow up the kitchen if youre not careful.