Cooking with Liquid Nitrogen

[dcarch]

I am wondering if you fill your refrigerator with Nitrogen, how much longer your food would stay fresher.

dcarch

[Chris Amirault]

OK, I think I get the caution part. I'm utterly terrified, in fact.

So now the question is whether there are things that are cool/interesting enough to try using the stuff. Those of you who have used it at home, what did you do with it?

[CFT]

I am wondering if you fill your refrigerator with Nitrogen, how much longer your food would stay fresher.

I think there is a distinct possibility your refigerator might go KAPOW!

[CFT]

So now the question is whether there are things that are cool/interesting enough to try using the stuff. Those of you who have used it at home, what did you do with it?

I thought ice creams and sorbets might be the extent of it. I'd like to know what else you could do with it too.

[Mayur]

"Shaking" drinks. It's also good for enabling quick spherifications and freezing things you can't otherwise really freeze. Come summer, I'd like to try it for some frozen sazeracs and the like, for instance; standard frozen proportions don't work well with classic cocktails (see HERE), but I'm curious as to whether you could cut dilution, subtract heat, and end up with a tasty product.

Edited March 2, 2011 by Mayur (log)

[gfweb]

One could certainly have a LN2 cooled freezer, but it would be a serious engineering project and not a DIY job. Dry ice is far more practical.

Re Dewar vs thermos- really two versions of the same thing. Dewar is sturdier, comes vented and is more expensive. Thermos is cheaper and can be made as safe as a Dewar with a drill. I've used a thermos and a Dewar for years. Both work well.

Don't be terrified. It really is safe stuff so long as you don't have it in a sealed container and use your head.

[CFT]

Oven gloves and safety glasses.

[Chris Hennes]

So now the question is whether there are things that are cool/interesting enough to try using the stuff. Those of you who have used it at home, what did you do with it?

In Modernist Cuisine they seem to use it a lot to prevent overcooking meats when deep frying and things like that.

[dcarch]

------------------- It really is safe stuff so long as you don't have it in a sealed container and use your head.

I don't understand. How do you use your head to store LN?

dcarch

[gfweb]

------------------- It really is safe stuff so long as you don't have it in a sealed container and use your head.

I don't understand. How do you use your head to store LN?

dcarch

I could give you a list of people who apparently are doing just that.

[davidkeay]

Oven gloves and safety glasses.

I'm going to have to argue with the oven gloves - all my oven gloves are heat resistant cloth. If you spilled liquid nitrogen on them, they would soak it up and hold it to your skin while you scramble to pull them off. It's the same reason I'd sooner work with LN in bare feet than with socks on.

Sealed silicone gloves, on the other hand, would work great.

[davidkeay]

A good thermos alternative is an airpot - the insulated coffee thermoses you see on bad conference buffets. I have this one and it works great. The top doesn't seal, so you get venting without drilling a hole in it, and at 2.5 liters it's bigger than most thermoses. (I picked up this tip from cooking issues). I don't know how long a couple liters will last in an airpot like that, since I've never tried to hold it more than 12 hours or so. In my experience, I lost maybe an inch of the stuff over the course of the day, so it doesn't seem too bad.

As far as safety, I do try to keep in mind that it's a colorless/odorless gas that you won't even notice is suffocating you. I don't get it for parties when we'll have toddlers and pets around, and I do make sure everyone knows what to do (leave the house!) if the container spills.

[emannths]

I'm going to have to argue with the oven gloves - all my oven gloves are heat resistant cloth. If you spilled liquid nitrogen on them, they would soak it up and hold it to your skin while you scramble to pull them off. It's the same reason I'd sooner work with LN in bare feet than with socks on.

Sealed silicone gloves, on the other hand, would work great.

Another reason not to use absorbent gloves is because they will absorb the copious condensation that results from LN2 usage. If you've ever used a damp potholder, you know that wet cloth conducts heat much faster than dry cloth.

[Shalmanese]

I am wondering if you fill your refrigerator with Nitrogen, how much longer your food would stay fresher.

dcarch

It's an interesting question, I asked it on the Cooking Issues forum: http://www.cookingissues.com/forums/viewtopic.php?f=33&t=2579 to see if anyone is willing to do an experiment.

[davidkeay]

That is interesting. For some reason, I had been under the impression that nitrogen was denser than our atmosphere, but I was wrong...it looks like it's specific gravity is .97 or so, so it's just a little bit lighter than the air around us.

putting some into a bottle of wine is definitely an interesting idea.

[PetersCreek]

Edit: Having offered that advice, I have a question of my own for all the other LN2 users out there: A local hardware store carries liquid nitrogen, but specifies that it's not food safe. I think it's cool that they felt the need to specify that, but it made me wonder: how can it not be food safe? Is this something I actually need to worry about, or are they just covering themselves legally?

I've never used LN2 in food applications but I did use it and gaseous N2 in military avionics applications.

Some gases contain petroleum products used to lubricate compressors, inhibit rust in storage bottles, and what-have-you. We purged and pressurized our components with "dry nitrogen", a mix of 95% N2 and 5% O2, that was certified free of oil and other contaminants.

My guess is that the LN2 your hardware store carries wasn't condensed under food safe conditions. Remember, small amounts of contaminants in a gas can be greatly concentrated during liquification, depending upon the process used.

[Msk]

I've had frozen drinks made with LN, and the texture is amazing. Literally like pudding with no discernable texture from the ice crystals. Also its cold enough to do this to pure alcohol, so no dilution!

[Kerry Beal]

OK, I think I get the caution part. I'm utterly terrified, in fact.

So now the question is whether there are things that are cool/interesting enough to try using the stuff. Those of you who have used it at home, what did you do with it?

I poured chocolate into it to make some nest like pieces. Made ice cream with really nice small ice crystals in the kitchen aid - very smooth.

Use dry ice in my panning.

[davidkeay]

In terms of pure novelty factor, frozen honey was very interesting. I froze about a tbsp of it by dropping it into about 1/4 cup of LN, and then broke it up with a fork (and hammer) once it was frozen solid. I ended up with crystals about 1/2 the diameter of a pea that looked like glass. When you bit into one, it would make an amazingly loud squeaky-crunch. It's a little hard to describe, but it shatters in your mouth in an interesting way (right before it melts into honey, of course). It reminds me a little of the way that cornstarch suspended in water behaves both like a viscous liquid and a solid at the same time.

[LoftyNotions]

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.

That works out to replacing approximately 7.7 percent of the room air. With air being about 21 percent oxygen that would bring the room oxygen level down to around 16 percent.

17% O2 level causes anoxia

10-14% O2 level causes dizziness

6-8% O2 level causes collapse

Less than 3% O2 causes death within 45 seconds

Of course, a spill in a smaller enclosed area such as a car would have much more dire consequences than a spill in an open area as would a spill of a much larger quantity.

As far as protective clothing goes, definitely wear at least safety glasses or goggles if not a full face shield. As mentioned above, absorbent clothing such as oven mitts can be more dangerous than bare skin. We wore Welder's gloves when doing liquid nitrogen and liquid helium transfills. The silicone gloves would work very well in this application.

[dcarch]

"---The silicone gloves would work very well in this application. "

Can we verify that?

Silicone rubber is about from -55°C to +300°C while still maintaining its useful properties. At LN temperature would silicone become very brittle?

dcarch

[LoftyNotions]

"---The silicone gloves would work very well in this application. "

Can we verify that?

Silicone rubber is about from -55°C to +300°C while still maintaining its useful properties. At LN temperature would silicone become very brittle?

dcarch

I wasn't thinking in terms of long term immersion in liquid nitrogen. I'd use them more for short exposure and to protect myself from exposure to objects chilled by the nitrogen. I watched an old Iron Chef episode last night where Homaro Cantu was submerging objects with his bare hands.His hands were actually in the liquid nitrogen for brief periods. I wouldn't personally long term immerse either my bare hands or hands covered with any kind of glove. I guess the easy way to answer your question would be to immerse a glove (sans hand)and see what happens.

One other piece of advice regarding gloves/mitts... they should be loose enough to shake off if you need to.

Best bet: Buy a pair of welder's gloves. Worst bet: Use regular cloth oven gloves. Better than nothing: Silicone mitts.

By the way, Cantu didn't wear any protection, so I wouldn't use him as a good safety example.

Hopefully this clears up my thinking at least a little.

Thanks,

Larry

[tomdarch]

"---The silicone gloves would work very well in this application. "

Can we verify that?

Silicone rubber is about from -55°C to +300°C while still maintaining its useful properties. At LN temperature would silicone become very brittle?

dcarch

I haven't re-read the Cooking Issues guide to LN2 in a while, but I think I remember comments about selecting protective gear in part on "what happens if LN2 pours into the cuff." The downside to silicone mitts is that if some quantity gets into the glove, it will be trapped against your skin. This might be even more of an issue with welders' gloves, which have an even wider, shorter "cuff" or "gauntlet." The same issue stands for selecting shoes...

That said, I suspect that using a small quantity of LN2 at home for "novelty" purposes is a lot different than using it day in and day out at a restaurant. At home, you're approaching it with wide-eyed caution and a bit of "beginners mind," where at work, you may get lax.

Another use I've for LN2 is "herb dust" - freezing fresh herbs, then crushing them into a fine powder, which thaws back into a dust of fresh herb flavor. I also recall seeing Cantu and the MOTO guys making "juice balls" working with LN2 bare handed. They put a few tablespoons of juice (beet, in this case) into a normal balloon, filled it with a bit more air, and tied it shut. They then rolled the juice/air filled balloon around on the surface of the LN2. The juice froze on the inside surface of the balloon, freezing into a hollow sphere. They cut the balloon away, leaving the sphere to be plated.

[LoftyNotions]

I haven't re-read the Cooking Issues guide to LN2 in a while, but I think I remember comments about selecting protective gear in part on "what happens if LN2 pours into the cuff." The downside to silicone mitts is that if some quantity gets into the glove, it will be trapped against your skin. This might be even more of an issue with welders' gloves, which have an even wider, shorter "cuff" or "gauntlet." The same issue stands for selecting shoes...

That's part of the reason for only wearing a glove/mitt that can be shaken off. Welding gloves were standard wear for us while handling cryogens.

As far as thermal hazard is concerned, we work with oil heated to 375 F and don't think too much about it. Given a choice of quickly dunking my hand in LN2 or hot oil, I'd take the LN2 any day.

It's a tool that should be understood and respected, but not feared.

[Hayley Casarotto]

I use LN2 at work (science, not food-related). I tend to wear two layers of gloves - rubber on the outside for lack of permeability, thick cloth on the inside for insulation.

Like many have noted, if you do the right thing and treat it with respect, then it's nothing to be afraid of. Having said that, I'd like to emphasize this - please please please please wear safety goggles. If it gets on your skin, the residual heat your skin produces will stop it from burning you right away, and you can usually brush it off without any problems. If it gets in your nice wet eye, your eye will freeze. Immediately. So please, if you do nothing else, wear proper eye protection. I've seen the pictures so you don't have to.

Kudos to everybody who has spoken about air displacement already. We transport it on the back tray of a ute (I think that's a pickup to Americans?) rather than in the cabin.

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!