Cooking with Liquid Nitrogen

[blue_dolphin]

Oven gloves and safety glasses.

...As far as protective clothing goes, definitely wear at least safety glasses or goggles if not a full face shield....

...I'd like to emphasize this - please please please please wear safety goggles....

Another vote for eye protection. You do not want this stuff, even a droplet, in your eyes! It's way more prone to violent boiling than hot oil so extra caution is really appropriate.

I've only used LN2 at work, in a lab. The only food related "experiment" I remember was eating LN2 dipped graham crackers and blowing smoke rings.

[davidkeay]

One more thing - submerge your tools (ladles, tongs etc) into it slowly, rather than dunking them on in, to avoid any violent boiling over. Other than that, have fun!

This is a good point that I forget about when I tell people how to handle the stuff. Since I store mine in an airpot, I use the built in metal straw and pump mechanism to dispense it. When I go to actually insert the straw and pump into the LN, I have to go slowly. If I insert it too fast, the boiling action will cause LN to actually spray out the end of the straw... dramatic, but definitely not something you want happening by surprise.

[LoftyNotions]

One more safety precaution I don't remember seeing here is to remove all rings, bracelets and metal watches before handling LN2.

On another note, for those who feel that welding gloves or silicone mitts are not sufficient protection, here is another (more expensive) option:

http://www.2spi.com/catalog/supp/cryo-gloves.php

[avaserfi]

I just found a local welding supply place that sells liquid nitrogen by the pound. I am really excited about starting to work with the substance, but won’t be able to get a dewar since they are too expensive. I called the welding supply and asked for suggestions. They said they have people come in with plastic coolers (although they did point out that the interior plastic does crack), styrofoam coolers and dewars.

Given my situation and the fact that I won’t need a lot of liquid nitrogen at a time (cooking for 2) does anyone have any suggestions? It seems a small plastic cooler would be the least expensive option, but might not be safe? Alternatively I was thinking about getting a 1-2 liter thermal carafe and making it (or making sure) it is vented.

Would 2 liters be enough to get some experience with the technique or would it sublimate too quickly from a thermal carafe for practical use?

I don't have a truck for transport, so at best I can keep it in the trunk on the drive home. Does

[gfweb]

I think there'd be too much sloshing with a cooler in a trunk.

I'd buy a big thermous and drill a small hole completely through the cap to vent it. This is critical. LN2 will go off like a bomb if kept sealed. The only shortcoming of using a drilled thermous is that it loses a bit more N2 than a Dewar since the internal pressure is a bit lower.

If you did use a styrofoam cooler perhaps some baffles could be put in to keep the sloshing down.

Whatever you end up using, venting is critical.

[bmdaniel]

You could probably use the vacuum insulated coffee dispenser Dave Arnold recommends (or two) - he says it loses 50% of its volume in 24 hours, so it will probably work if you just want to use it for a day or two.

http://www.cookingissues.com/primers/liquid-nitrogen-primer/ - scroll down about a quarter of the way

[avaserfi]

I think there'd be too much sloshing with a cooler in a trunk.

I'd buy a big thermous and drill a small hole completely through the cap to vent it. This is critical. LN2 will go off like a bomb if kept sealed. The only shortcoming of using a drilled thermous is that it loses a bit more N2 than a Dewar since the internal pressure is a bit lower.

If you did use a styrofoam cooler perhaps some baffles could be put in to keep the sloshing down.

Whatever you end up using, venting is critical.

I will most definitely allow the vessel to vent. In the Cooking Issues primer they recommend against keeping the LN2 in the passanger portion of a car. The trunk is the best I can do, but I can drive carefully and keep the vessel held in place in a larger box to prevent/minimize sloshing.

You could probably use the vacuum insulated coffee dispenser Dave Arnold recommends (or two) - he says it loses 50% of its volume in 24 hours, so it will probably work if you just want to use it for a day or two.

http://www.cookingissues.com/primers/liquid-nitrogen-primer/ - scroll down about a quarter of the way

Yeah I saw the dispenser he recommended, but don't know enough about them to know what to order. Do you have any idea on the type they use?

[bmdaniel]

Yeah I saw the dispenser he recommended, but don't know enough about them to know what to order. Do you have any idea on the type they use?

I would just run to a restaurant supply - I am sure they will have them and you can make sure they are vented before you buy.

Otherwise, you can get something like this on Amazon for $28, but I can't be sure it vents naturally(probably does, but you may have to return if not)

[Judy Wilson]

One of our culinary research assistants just blogged about his experience with liquid nitrogen, which he's been cooking with for more than five years. So far, only one bad incident to speak of!

But basically he says a lot of what has been said here: wear gloves, don't use it in closed, unventilated areas, wear shoes that aren't made of fabric (in case some drips on your foot), etc.

[paulraphael]

I just did some rough calculations of what amount of air 2.5 liters of liquid nitrogen would displace. At 700 X expansion, it would displace 61.8 cubic feet of air. Assuming you're in a sealed room measuring 10 feet by 10 feet by 8 feet, the room holds 800 cubic feet of air ignoring cabinets, people, etc.

The trouble is that LN2 and air won't mix evenly. The LN2 will generally dsplace most of the air in the lower half of the room. The other trouble is that unlike C02, it doesn't make people ghasp for breath. People just get sleepy and lie down, often dramatically.

I think the most important precautions, mostly already mentioned are:

1) unsealed (and unsealable) container

2) safety goggles. a drop splashed in your eye can be very, very bad

3) ventilation

4) no clothes that could accumulate LN2 and hold it next to your skin (boots that are open at the top, etc...)

If you spill the stuff on open skin it just rolls and boils off. But if it ends up inside a glove or a shoe, with nowhere to go, you can get instant and extreme frotbite. I don't think full lab saftey gear is necessary ... my scientist friends who work in actual labs don't bother with it ... but some basic precautions like pants cuffs pulled down over your shoes, long, unabsorbent gloves (if you're wearing gloves at all), etc., are smart precautions.

[Skywater]

My local suppliers will only sell you liquid nitrogen if have a dewar or rent one of theirs.

[mkayahara]

My local suppliers will only sell you liquid nitrogen if have a dewar or rent one of theirs.

As they should. Transporting liquid nitrogen in any other container is just asking for trouble.

[Broken English]

How much is it on average?

Also, Heston Blumenthal was on The Jonathan Ross Show and he was dsipping his bare hands into it and flicking it at Ross, which made for quite an amusing scene. Extrapolating from this, I'd assume that it's okay to touch, if only very briefly.

[Dexter]

I know this is super late, but a professor of mine in college called it the Leidenfrost Effect - basically the same thing that makes droplets of water skitter across a hot surface without just sitting down and boiling away. A layer of rapidly forming vapor insulates the warm and cold bodies, and keeping them slightly apart. He demonstrated it by holding his hand out, fingers together, like he was sticking his hand out to shake someone elses', the poured LN2 over the top. Did it to a couple of students too. Made the point stand out in my head, even 20 something years later.

[Dexter]

Actually, now that I've gravedug this particular thread, I might as well drop this question in here as well:

Does anyone know of a good, smallish (2 person household, guests on occasion) Dewar they'd recommend, and a place that sells them? Getting it filled up isn't as much of a problem, but I'm hesitant to going the Ebay route for this kind of equipment.

[msacuisine]

I'd like to pick up a liquid nitrogen dewer, but they seem quite expensive, so I want to make a good choice. Does anyone have advice on the best size for kitchen use? Where are some sources to procure one at a reasonable price? Any other advice about purchasing one?

Thanks.

[gfweb]

You can use a old fashioned thermos with a glass liner SO LONG AS YOU DRILL A VENT HOLE IN THE CAP TO PREVENT EXPLOSIONS. I have done this for years quite safely. The only downside is the small volume of most thermoses.

You could probably use a insulated plastic drink carboy like you see at picnics or construction sites to get a larger volume. SO LONG AS YOU DRILL A VENT HOLE IN THE CAP TO PREVENT EXPLOSIONS.

Don't forget the vent.

[Smithy]

Good advice, gfweb.

Where does one go to get liquid nitrogen with which to fill the carboy, or the thermos bottle, or the dewer, for home use? Is it becoming widely available outside the major cities? I'm curious about this, having only ever acquired LN₂ in small quantities from the university chem lab.

[gfweb]

That's where I've always gotten mine.

[Panaderia Canadiense]

I get mine at a chemistry supply house. But since I'm in Ecuador, ymmv.

[Smithy]

That's where I've always gotten mine.

Is it because you have an "in" with the stock person, or do they allow you to purchase it? I suppose I'll have to ask my local universities, if I decide to pursue this, what their policy is.

[Kerry Beal]

Companies like Praxair that supply gasses to industry and for medical purposes have liquid nitrogen. Also dry ice.

[gfweb]

I only use the LN2 at work so no subterfuge is needed.

Kerry's suggestion is a good one.

[Kerry Beal]

To be honest - work is where I get mine too! But my dry ice I get from Praxair (he trades me for chocolate!)

[Samir Chopra]

Has anyone in the bay ares been able to purchase liquid nitrogen with any success?  I've tried contacting Praxair near San Francisco but they did not allow me to purchase any LN2 from them.