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

Popular Science ^ | July 2003 | Theodore Gray

[mhking]

Liquid nitrogen is cold. Very cold. So cold that if a drop falls on your hand, it feels like fire. So cold that it can turn a fresh flower into a thousand shards of broken glass. So cold that it can make half a gallon of ice cream in 30 seconds flat.

I first heard about liquid nitrogen ice cream from my friend Tryggvi, an Icelandic chemist working in the Midwest (these things happen). He suggested we make it for dessert at a dinner party I was planning. Yes, he said, he had a recipe, something he'd seen in Chemical and Engineering News.

Now, right off the bat you have to worry about a recipe found in Chemical and Engineering News, the principal trade publication for the sort of people who build oil refineries, shampoo factories and large-scale plants for the fractional distillation of liquefied air (which is where liquid nitrogen comes from). But for the party I was planning, it was perfect: The well-known author Oliver Sacks was coming to visit with my collection of chemical elements; I needed some after-dinner entertainment.

My first concern was whether we would survive the ice cream. That and, if it didn't kill the cook, whether it would be any good. I had visions of hard, crusty stuff that caused frostbite of the throat. It turned out nothing could be further from the truth.

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.

The kids were amused by the clouds of water vapor, though being kids they didn't find anything out of the ordinary in the procedure. They probably think everyone makes ice cream this way. Boy, will they be in for a shock the first time they see it done the old-fashioned way at camp: You want me to do what for a half hour?

A word of caution: Liquid nitrogen can be dangerous in careless hands. Tryggvi and I are both trained chemists, and he actually knows what he's doing. Don't try anything like this unless you do too.

[supercat]

I wonder how well pulverized dry ice would work.

Carbon dioxide would likely add an 'off' flavor.

[drlevy88]

Yeah, maybe a bit acidic. On the other hand that wouldn't be bad for a sherbet.

[prisoner6]

Sadly those pages have been removed by the Net Nannies. The only one left I know of is....

Barbecue

The videos on the old pages WERE REALLY COOL!... Hot acutally.

This ice cream would be the perfect wrap up to a 'Better Living Through Chemistry" picnic.

prisoner6

[drlevy88]

Well it really isn't chemistry. It's physics.

[rmh47]

Many years ago, when I was a technician in a lab that designed and tested air conditioners for a major appliance manufacturer, we used liquid nitrogen for pulling the charge out of units to measure the amount of freon in them.

The stuff was neat to work with. You could plunge your hand into the dewar flask without any problem as long as you pulled it right back out. You could cup your hand as you brought it out and hold a small amount of it in your hand as long as you kept tilting your hand back and forth to keep the liquid nitrogen from sitting in one place.

Apparently, the temperature differential between your body and the liquid nitrogen is so great that the radiant heat from you hand causes the stuff to instantly boil and forms an insulating layer of gas between them.

[Paleo Conservative]

Well it really isn't chemistry. It's physics.

It's Physical chemistry. What would be really cool would be to repeat this experiment at different pressures so a phase diagram could be constructed.

[supercat]

Apparently, the temperature differential between your body and the liquid nitrogen is so great that the radiant heat from you hand causes the stuff to instantly boil and forms an insulating layer of gas between them.

The Leidenfrost effect. If your dip your hand in water, you can then very briefly dip it in molten lead with similar non-effects, but only if the lead is hot enough. Otherwise very bad.

[HiTech RedNeck]

With either the lead or the liquid nitrogen I'd be afraid of splashes.

[Paleo Conservative]

The Leidenfrost effect. If your dip your hand in water, you can then very briefly dip it in molten lead with similar non-effects, but only if the lead is hot enough. Otherwise very bad.

Hopefully the producers of Jackass will not find out about the Leidenfrost effect

[ALS]

Actually a thermos does work, but you have to be veddy careful transporting and it won't last long, so use it quick!

Small chance they'll let you walk out with a thermos full though.

[Boiler Plate]

I wonder if these guys use lox as a barbecue starter?

I saw website from some guys at Purdue doing exactly that. They claim to hold the unofficial World Record in the fastest BBQ lighting category (unlimted class). It was unbelievable, they vaporized the grill in the process.

[Hillarys Gate Cult]

Another use for nitrogen that's well known around aircraft maintenance circles is it's use in vehicle tires instead of compressed air. It stops most all slow leaks.

[RippleFire]

bump

[Paleo Conservative]

It stops most all slow leaks.

Please explain why? Is it because pure nitrogen contains no water vapor?

[ccmay]

Well it really isn't chemistry. It's physics.

Of course it is. All science is either physics or stamp collecting.

-ccm

[Jubal Harshaw]

Not only do you not even need a thermos, but the small size of the thermos might be a problem. I used to make ice cream myself (as per the article above), using a styrofoam cooler of liquid N2 from my lab. The cooler ($3.00 at any grocery store, put one inside another for more insulation) held 2 1/2 gallons, which started to evaporate immediately, but would take hours to completely sublimate off. Of course, I was working in a place that bought N2 by the truckload, so a cooler of N2 was only a few cents.

[nightdriver]

Interesting. I've seen an experimental commercial venture to make ice cream this way. The process was continuous with the ingredients mixed with liquid nitrogen in a high-pressure nozzle and sprayed out into a container.

What landed in the container was ice cream dust - microscopic particles of very well frozen ice cream. It tasted great and had a very unique texture.

[prisoner6]

Oopsies! LOL, Yeah I realized that after I posted...sigh.

prisoner6

[AnalogReigns]

Where does a layman buy liquid nitrogen???

[MHGinTN]

Easy sherbet-like recipe is to use Orange, Rasberry, or even Root Beer soda, with Eagle brand and 1% milk (with organse you can also add mandarin orange pieces, crushed); use a large stainless steel bowl into which you crumble up ~3 to 4 cups of dry ice and immediately place a secomd smaller stainless steel bowl with the mixed liquid in it pushed down into the dry ice; while someone turns the smaller bowl, fold the liquid ingredients using a mixer on lowest speed ... dessert in three minutes, but you have to switch to a large slotted spoon before the dessert hardens completely. I have yet to try it with my wifes countertop mixmaster ... she doesn't yet trust the solidifying mass to not burn out her motor!