51 replies to this topic

[Chris Amirault]

I think that I'm going to try to score some liquid nitrogen. My use of the verb "score" should indicate the level of thrill-seeking risk I imagine. Whatever those pleasures, I also don't want to be silly about something potentially dangerous.

I know that the Modernist Cuisine book, which I haven't got handy at the moment, has a section on this, but I can also imagine that others here have experience, techniques, cautions, and the like.

[mkayahara]

My first and best advice: pay attention. It's not as dangerous as it's made out to be, but there are some real risks associated with it. Use it in a well-ventilated area, don't let it touch your skin for long periods of time, don't use metal utensils in it and let them touch your skin for very long (I gave myself frostbite that way once, because I wasn't paying attention.) Obviously, don't put it in a sealed container. Overall, pay attention!

Oh, and have fun with it! Be sure to take a drop of it and roll it across a flat surface to enjoy the Leidenfrost effect, freeze things solid and shatter them, and make spooky vampire voices over all the "smoke."

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?

Edited by mkayahara, 02 March 2011 - 08:12 AM.

[Chris Hennes]

I wonder if the container it is stored in was not cleaned to food-safety standards? Perhaps it has oil residue or the like? The same may apply to other equipment that was used to handle it. I don't know for sure, obviously, just guessing here.

[bmdaniel]

I have not used liquid nitrogen myself, but the cooking issues primer seemed pretty good (as their stuff usually is):

http://www.cookingis...itrogen-primer/

[gfweb]

The big big thing with LN2 is to NEVER put in a tightly sealed container. It will explode. Get a thermos and drill a hole through the cap so it can vent off pressure. A thermos is a good idea to slow evaporation of the LN2 and it is cheaper than the Dewar flask somebody will try to sell you.

[dcarch]

Just one liter of liquid produces around 700 liters of gas at atmospheric pressure, displacing significant quantities of breathable air if the gas is released in a confined space.

You can kill (suffocate) many people inside an elevator cab if your nitrogen container is broken inside an elevator.

The lack of oxygen in a confined space with a fire burning can also create CO.

dcarch

[Jeffery C]

I have not used liquid nitrogen myself, but the cooking issues primer seemed pretty good (as their stuff usually is):

http://www.cookingissues.com/primers/liquid-nitrogen-primer/

Yes, I second that! VERY informative, and leans toward the cautionary side of things. I too am looking to score a dewar of liquid nitro, but will probably find a local chef that has experience walk me thru the paces first.

[Brown Hornet]

Great and timely topic!

I've been curious about this as well, and have frankly been a little too scared to bring some home, especially with a three year old around the house. That said, I'm completely ignorant as to the real vs. imagined hazards of liquid nitrogen. For example, I fry stuff all the time, and a hot oil spill is probably more dangerous than a liquid nitrogen spill. Then again, I had no idea about the sealed container issue! There's so much I don't know about this stuff.

I guess my big question is what are people doing to store it and what quantities are practical for purchase and storage at home. Also, how long does it last? Given that a proper container must incorporate some ventilation to release pressure, it seems like you would also have significant loss from evaporation.

[Chris Amirault]

I have not used liquid nitrogen myself, but the cooking issues primer seemed pretty good (as their stuff usually is):

http://www.cookingissues.com/primers/liquid-nitrogen-primer/

Jeebus: that UC Davis report is pretty sobering, especially the pix.

[lancastermike]

Airgas Corporation has a plant several miles from my house and one of my neighbor’s works there. On occasion he has brought some home to play with. Not culinary uses. Just for laughs. He is very safety conscious with it. The container he transports it in looks like a heavily insulated five gallon gas can. He always tells me that most people understand that it can cause serious freezer burns, but most have no idea of the dangers of oxygen replacement. In the industrial enviorment he tells me the oxygen replacement danger is of a greater concern than the thermal one. I've seen him freeze all sorts of things and shatter them for effect. But he does this outside.

I have no advice on how it works in a culinary fashion, but I also urge caution with it as I have seen what it can do.

[mkayahara]

I guess my big question is what are people doing to store it and what quantities are practical for purchase and storage at home. Also, how long does it last? Given that a proper container must incorporate some ventilation to release pressure, it seems like you would also have significant loss from evaporation.

Personally, I would never store or transport it in anything but a purpose-built Dewar. I'm not sure what the evaporation rates are like, but there is certainly some loss over time, so I'd buy it in small quantities and use it promptly.

Edit: Heard back from a friend, who says his supplier told him that 10 litres would take 40 days to dissipate from a Dewar.

Edited by mkayahara, 02 March 2011 - 09:14 AM.

[CFT]

I used to use LN for my graduate research (characterising semiconductor materials at low temp). There used to be a big pressurised tank of it in the basement of the building. Every so often I would trundle down with a large spherical dewar (polystyrene stopper) in a wheeled mount that allowed it to be transported and allowed tipping out. This was my "stash" - can't remember how long it lasted - maybe a week or two.

On a "per experiment" basis, I would fill a big polystyrene bucket with as much LN as I needed to fill a small cryostat. I was aware of the oxygen/air displacing properties but the lab was sufficiently ventilated.

Edited by CFT, 02 March 2011 - 09:20 AM.

[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 by Mayur, 02 March 2011 - 10:14 AM.

[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.cookingis...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.