86 replies to this topic

[nathanm]

Who is cooking with liquid nitrogen? What are you doing with it? This is a topic that is at the cutting edge of culinary technique, but there is very little information out there about it.

Liquid nitrogen is a clear liquid (looks just like water) but it is extremely cold - 320F / -196 C. It has been used scientifically for over 100 years, and has many industrial uses. Most people abbreviate it LN2, because N2 (with 2 as a subscript) is nitrogen molecule in the air.

A number of chefs are using LN2 in various ways. LN2 ice cream has been around for many years as a science demonsration, and there are many web sites about it such as this one. If you search for "liquid nitrogen" and "ice cream" you get 16,000 hits on Google so this is not exactly unknown. Heston Blumenthal likes to point out that the first reference to LN2 ice cream was in the 19th century. However, apart from the cool presentation there are a lot of other (and probably better) ways to make ice cream.

LN2 can be bought at welding and medical supply places. It is pretty cheap - $0.20 to $0.25 per liter. That is less than $1 a gallon - cheaper than milk, gasoline, or bottled water. The only expensive part is that you need a large thermos - called a Dewar to store it, and these can run $500 to $1000. However, they do exist on eBay for less.

Because of the intense cold, LN2 is dangerous. However, we need to put that in perspective - boiling water is dangerous too, and a hot oil in a deep fryer is also dangerous. Realistically speaking, LN2 is no more dangerous than these.

Heston Blumenthal serves an amuse bouche that is a small ball of foam frozen with liquid nitogen at tableside. Dani Garcia , until recently at Tragabuches in Ronda also cooks with it and has a short chapter in his cookbook on it (in Spanish).

This web articlementions a couple other chefs using it. Ferran Adria of El Bulli has spoken publically about making an LN2 chilled version of a plancha - the cold version of a hot griddle. Instead of heating food in contact with the griddle it would be chilled.

I will confess that I have not used LN2 yet for cooking myself, but did use it in graduate school scientifically. I'm about to gear up to trying some LN2 cusine, but I thought I'd canvas eGullet first to see who else is into it, and whether there are any practical ideas, tips etc out there.

[McDuff]

Can you huff it?

[wattacetti]

While I was in grad school (and when it was plentiful) I used liquid nitrogen a couple of times to make a vodka granite (vodka, simple syrup, cold - not particularly good) and vodka ice cubes. Interesting, but at the time that was about it. The stuff gave quite the kick, especially when people would suck on the ice cubes after they had finished their drinks.

You'd want to use the transport dewar and not draw N2 from the tank used to store cell lines.

[Patrick S]

Heston Blumenthal likes to point out that the first reference to  LN2 ice cream was in the 19th century.  However, apart from the cool presentation there are a lot of other (and probably better) ways to make ice cream.

Actually, Ive heard that LN2 is the best way to make ice cream, because the super-rapid freezing insures a very small crystal size and thus a super smooth, creamy texture.

[nathanm]

LN2 ice cream is very good, but it is unclear that it is better than excellent freshly made ice cream right out of the machine (conventional or pacojet) which also has small crystals.

LN2 is a great presentation for making ice cream if done as a demo, or done tableside - lots of drama, sort of like doing something flambe at the table just cold instead of hot. But I am skeptical that there is a reason to do it apart from the fact that it is a dramatic demonstration.

As to huffing it.....well you ARE huffing it right now! About 78% of the atmosphere is N2. Nitrous oxide is a very different issue - that does cause euphoria (laughing gas), but that is a DIFFERENT gas altogether.

[edsel]

Actually, Ive heard that LN2 is the best way to make ice cream, because the super-rapid freezing insures a very small crystal size and thus a super smooth, creamy texture.

I'm thinking that texture is the key here. Sorry that I can't contribute any first-hand experience. If Ferran Adrià is excited about his N2 "plancha", I'm excited too!

[Patrick S]

Actually, Ive heard that LN2 is the best way to make ice cream, because the super-rapid freezing insures a very small crystal size and thus a super smooth, creamy texture.

I'm thinking that texture is the key here. Sorry that I can't contribute any first-hand experience. If Ferran Adrià is excited about his N2 "plancha", I'm excited too!

I have actually tried ice cream made with LN, called 'Dippin' Dots.' They were very good. I didnt realize you could buy small quantities of this stuff, so there is a good chance I might actually try to make some myself.

[Patrick S]

LN2 is a great presentation for making ice cream if done as a demo, or done tableside - lots of drama, sort of like doing something flambe at the table just cold instead of hot.  But I am skeptical that there is a reason to do it apart from the fact that it is a dramatic demonstration.

Are you skeptical that crystal size is related to smoothness of ice cream? Are you skeptical that crystal size is related to rapidity of freezing? Are you aware of any other method that takes your ice cream base from room temp to frozen in 30 seconds? It seems to me that there is a very obvious reason to do it apart from drama.

There is an interesting article from 2002 Scientific American on this. The author recounts his experience with LN ice cream thus:

We mixed up a standard ice cream recipe calling for two quarts of cream, sugar, eggs, vanilla and flavoring. (Just about any ice cream recipe and flavor will work.) Then, working in a well-ventilated area (lest the nitrogen displace oxygen from the air) and with due regard for the ability of liquid nitrogen to freeze body parts solid, we gently folded about two liters of nitrogen syrup directly into the cream, much as you would fold in egg whites.

The result, literally 30 seconds later, was a half-gallon of the best ice cream I'd ever tasted. The secret is in the rapid freezing. When cream is frozen by liquid nitrogen at –196°C, the ice crystals that give bad ice cream its grainy texture have no chance to form. Instead you get microcrystalline ice cream that is supremely smooth, creamy and light in texture. Martha Stewart, eat your heart out.

Behold the smooth, sweet powers of liquid N (Liquid nitrogen ice cream! Yum!)

Edited by Patrick S, 13 February 2005 - 08:28 PM.

[artisanbaker]

i have a good pic if a moderator can contact me. it's albert adria making sorbet.

[edsel]

I have actually tried ice cream made with LN, called 'Dippin' Dots.' They were very good. I didnt realize you could buy small quantities of this stuff, so there is a good chance I might actually try to make some myself.

I've had the "Dippin' Dots" at a food court in a Texas mall - My impression was that the limiting factor was the quality of the ingredients, not the technique. I don't doubt that in the hands of a true master the liquid-nitrogen ice cream could be sublime.

The "plancha" that so enthuses Ferran is a different matter. Forming a skin on the product via extreme freezing temperatures is somewhat unexplored territory - though Adrià has apparently done some research at the "Taller". Several eG members have scored reservations at El Bulli, so perhaps we'll get some reports about the success of the "plancha" later in the season.

[chiantiglace]

I always thought that using liquid nitrogen when making ice cream was somewhat goofy. It's great the people try new ways by I still wouldn't do it.

Compressed N2 is used widely as is compressed "air" to cool surfaces for products to set up like chocolate and sugar molds. Sometimes marble is cooled in this way before tabliering tempered chocolate. Compressed air is and excellent source for use in sculptures or attatchments when you need to cool two pieces together relatively quickly without holding them in place for 20 minutes, ha.

You are right about liquid nitrogen not being any more dangerous than a sizzling hot pan because the reverse temperature at those extremes do exactly the same thing as high temperatures which is destroying your cellular structure. It actually feels the same and leaves similar scarring, I actually had a couple.

The best thing about liquid nitrogen I think is it doesn't contribute anything to a product accept temperature. Considering air is 40% nitrogen it just heats up and evaporates within a couple of minutes leaving a product cold and uncorrupt flavor and texture wise.

I still thinks its kind of goofy, like an over done science project.

[Patrick S]

Maybe I dont have enough imagination, but I just cant see what's so goofy about producing great ice cream from a base in 30 seconds. In comparison, an ice cream machine looks goofy and overly laborious.

[docsconz]

How is the resultant ice cream not frozen solid? I like my ice cream soft and pliable, though not melted.

[Patrick S]

It would be entirely a matter of how much nitrogen you use. If you use too little, your ice cream would be too soft, if you use too much it would be too hard. There would be an optimum ratio of base to nitrogen (which I dont know).

[MelissaH]

I haven't tried making ice cream with liquid nitrogen. But if you want to try something else with food and liquid nitrogen that kids always go wild for: get yourself a bit of the cold stuff in a dewar with fairly low sides, and a bag of cheez puffs. (Not the ones like crunchy cheetos, for this you need the ones that are very puffy...as far as I'm concerned, the only good use for the puffy kind. ) Dip a cheez puff into the liquid nitrogen, and hold it there just until it gets good and cold. Use a big cheez puff, so you have something left to hold! Then pull the cheez puff out, and put it into your mouth. Hold it there, maybe chew on it a little bit. Voila: you've become a steam-breathing dragon!

The puffy cheez puffs are mostly air, which warms up pretty fast, so you're in no danger of freezing your mouth. If you chew on it, it feels about like chewing ice cream: definitely cold, but not cold enough to be uncomfortable. It's a great trick, especially for Halloween costume parties.

MelissaH

[docsconz]

It would be entirely a matter of how much nitrogen you use. If you use too little, your ice cream would be too soft, if you use too much it would be too hard. There would be an optimum ratio of base to nitrogen (which I dont know).

Makes sense. A recipe is important.

[nathanm]

My skepticism about LN2 ice cream being the best is that I wonder if the people who say that have had quality ice cream, made fresh by a great pastry chef. Ice cream that you get from a carton at the supermarket, or from an ice cream parlor, is just not the same thing.

[Wolfert]

I remember observing incredible dining room drama 10 or 15 times a night at Andre Daguin's Hotel de France in Auch back in the late 70's. An octogenarian named Rosalie (I could be wrong about her name) would roll out a cart and on it was a canister of liquid nitrogen and the stuff needed to make ice cream. She would do it tableside. Sounds and wisps of whatever went up in the air to make a memorable finale to a meal.

[Shalmanese]

My skepticism about LN2 ice cream being the best is that I wonder if the people who say that have had quality ice cream, made fresh by a great pastry chef.  Ice cream that you get from a carton at the supermarket, or from an ice cream parlor, is just not the same thing.

Yeah, ice-cream made by a french pastry chef would probably be better than generic LN2 ice-cream but ice-cream made by a FPC with LN2 would also undoubtably be better than normal FPC ice-cream.

LN2 is a technique, not an ingredient. The quality of the ice-cream you get out is still going to be dependant on the quality of the ingredients you put in but LN2 ice-cream just forms smaller ice-crystals.

[tan319]

The 'Plancha' that Adria is experimenting with reversing techniques on is, from what I've been reading, a 'Teppenyaki' grill, which they're using LN2 with.
artisanbaker, I would LOVE to see that Adria sorbet photo!

[MelissaH]

Well, some physicist friends and I just made some ice cream here in lab. The base was made from cream, half and half, sugar, natural cocoa, and chocolate syrup. I can't give you proportions because the only ingredients that were actually measured were the dairy products, since they came in and were used in increments of their specific-volume containers.

Anyway, we mixed up the stuff in a big metal bowl with a wooden spoon, tasting along the way and adding more chocolate syrup and cocoa along the way until we got something that tasted chocolatey enough but a little too sweet.

Then, one person stirred the mix while another poured the liquid nitrogen in, a little bit at a time. As it went in, it bubbled like mad (as you'd expect) and steam obscured the surface. The volume of mixture increased noticeably over the process. We'd also get some lumpiness, which would subside as the rest of the liquid transferred its heat into the frozen lumps. After a good bit of stirring (and liquid nitrogen) the ice cream thickened to about the texture of soft-serve. We kept on going, and eventually got a homogeneous mixture too thick to stir with our wooden spoon. At this point we waited a little bit for it to warm up, scooped it into our bowls, waited a little bit longer, and then ate.

My verdict: Very smooth and creamy. The most even-textured ice cream I've eaten in a while: no large crystals of anything anywhere. Could have used some more chocolate flavor.

I don't know that I'd go out of my way to do it again, unless I were trying to impress someone or I had extra liquid nitrogen to blow. But it was yummy!

MelissaH

[reachej]

Try starting with a ratio of 1:1 and adjust from there depending on the base.

[chefseanbrock]

we are using ln2 on a daily basis, we have been using it for about 6 months and now we can't live without it in the kitchen.......we have produced ice cream that is hot and cold at the same time using the ln2.......cold on the outside and hot on the inside.......we also are doing cocktails spheres that are liquid in the center and frozen on the outside........

[nathanm]

I just ate at ElBulli this week, and there were several terrific LN2 courses.

[nathanm]

Have been cooking with LN2 a lot the last several weeks - the results are very interesting.

The most popular thing with people I have forced this on is flavored whipped cream, shot out of an ISI cream whipper into LN2, then almost immediately removed and served. Crisp and hard on the outside and cream on the inside. If you eat it quickly, what looks like smoke comes out your mouth and nostrils.

Olive oil freezes solid. If you spray it in, you get a crystalline olive oil powder.

Thick liquids can be dropped, drop-by-drop and it will freeze into little balls.

This stuff is fun to play with - although you need a lot of safety precautions so "play" is perhaps not quite the right word.

[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.