Instructables

Make layered ice-creams with liquid nitrogen

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Ice-cream made with liquid nitrogen (LN2) is the smoothest you'll ever taste, because it freezes so fast there is no time for large ice crystals to form. Here's a simple way of making layered ice-creams using LN2.

Warning: LN2 is ridiculously cold (it is at its boiling point of 77 K, or nearly 200 degrees Celsius below zero) and hence is inherently dangerous. Do not try to ingest it. Make sure anyone around LN2 understands its perils (Material Safety Data Sheet). Drunks should be kept well away. Do not attempt to confine it. I strongly recommend using a thick-walled polystyrene container to hold it in while making the ice creams; definitely do NOT use a cheap glass-walled vacuum flask: there is an appreciable probability of it cracking and imploding, which trust me, is utterly indistinguishable from exploding.
 
 
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Step 1: You will need...

- some sort of sweet treat that can be embedded on a stick. We mostly used mini Mars bars, but jumbo marshmallows and brownies worked well too
- popsicle sticks
- sugar
- eggs
- half-and-half cream
- vanilla flavoring (or whatever you happen to like)
- food coloring
- a few liters of liquid nitrogen (obtainable from a supplier like Praxair or Airgas, if you have a dewar to hold it in)

Step 2: Make ice cream mix

Picture of Make ice cream mix
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This recipe comes from Nigella Lawson's "How to Eat", but I don't think there is anything especially unusual about it; it's just a custard-style ice cream. It's pretty good, even after we simplified it.

Whisk 5 egg yolks with 125 g of sugar until thick and creamy. Add to a large saucepan with 500 ml of half-and-half milk/cream, and stir over moderate heat for about 10 minutes, stirring constantly. Remove from heat and whisk again. Add flavoring (we used a teaspoon of vanilla essence) and coloring and put in refrigerator until ready to serve.

We made 2 batches of this and divided it into three jars (red, blue and uncolored cream).
pihudkeke3 months ago
Oh I thought yo
lperkins1 year ago
If you're making them ahead of time, put them in the regular freezer when you're done where they will cheerfully warm up to eating temperature, but not melt.
Thank you Silvester10528 I'm a gourmet cook and when I 1st read this Make layered ice-creams with liquid nitrogen I just had to investigate. My main stay and focus for several years now is eating organic,heart smart and GMO free. So thank you again for clarifying the necessity of using food grade nitrogen. I believe the author owes a duty to it's readers to stipulate this the article. If not, from a legal stand point could be held liable for all kinds of lawsuits.
makendo (author)  trueintegrity1 year ago
Warning: the ingredients in this instructable are not organic or heart smart.
gammerguy1 year ago
great job but where am I suppos to get a dewar and liquid nitrogen
That first picture looks like a turkey leg to me... :-)

Good idea to stress the safety points as much as you did, this LN2 can be seriously dangerous if not given the proper respect.

I think you have a decent chance of getting LN2 from most restaurant CO2 suppliers, but you should call them a good week in advance to see if they have any or even carry it at all. Food grade CO2 is NOT the same as paintball/airgun CO2, you can NOT get it from a welding gas supplier or fire extinguisher service outfit - so they will obviously not have food grade LN2, even if they happen to have LN2 in stock. Non food grade gases have machine oils infused in them that will likely make you ill.
No such thing as foodgrade CO2. Gas is gas. You cannot infuse oils into a gas. Paintball tanks would gum up the mechanisms if there was any oil in them. Not only that, as a gas expands it gets cold and the oil would get very gummy and that would be a problem in any CO2 system.

Also no such things as food grade LN2. It is just liquid nitrogen. Any oils, or anything else really would be frozen and could potentially clog up the dewar or the nozzle that the LN2 would come out of, so there is nothing in an LN2 tank other than LN2.
yeah, there is definitely such a thing as food-grade and normal gases. google it
I very much disagree with you.

I have been playing paintball since 1988 and I (like most) add airtool oil into the valve of my semi autos (mine are mechanicals, but the electro-pneumatics require it as well to lubricate the seals); the oil absolutely does NOT gum up the mechanism. The only thing that has ever gummed up one of my markers has been lithium grease at temps lower than 60 degrees F.

You are correct, "infused oil" is not be the correct phrase. The major difference is the manufacturing of the containment vessel and purity of the gas. "Food Grade" CO2 is indeed a real classification that is related to the impurities concentration in the gas and is regulated in the US:
http://fins.actwin.com/aquatic-plants/month.9611/msg00025.html
http://www.gasworld.com/specialty-gas-report/carbon-dioxide-in-food-and-beverages/2000207.article
You'll note that the impurities in "industrial/commercial grade" CO2 include hydrocarbons like Benzene (a carcinogen) and the unlined containment vessels have no requirement to be cleaned after manufacturing; given the process, they more than likely contain machine oils and probably metal shaving that you do not want to ingest.
http://www.homebrewtalk.com/f11/industrial-vs-medical-grade-co2-372270/
http://thebrewingnetwork.com/BN-Army-Blog/C02-Myths-and-Rumors
Why did you even bring up CO2 in the first place? I see no mention of it ANYWHERE in this Instructable.

(For the record, yes, i see there are two classifications of gas--but it is MOSTLY the handling and transportation of the gas, and not the purity of the gas itself.)
I work with high purity gases all the time. Nitrogen & CO2 are some of them. There are quite a few different grades. 4.0 (99.99%) gas wouldn't work at ALL for me.
Apparently it is jump down my throat day...

Yes. I am aware that you can purchase/request different purity/levels of gas, and if you absolutely positively HAVE to have the utmost pure gas ever--someone somewhere is going to be willing to sell it to you for many [units of currency].

But what I was saying is that most of the difference between the two classifications that we were talking about here, in this thread, is that for food grade is that the gas has to be handled properly. The actual gas content is not all that critical, because most of the time the gas suppliers are not going to have two tanks of almost-the-same gas, they are just going to have the gas that meets the food grade requirement, and they just handle the refilling of the tanks differently.

The thing that gets me is that this post isin't even about CO2 at all--it is about Liquid N2!
My apologies, I was having a rough day at work and did not mean to jump on anyone.

The point about CO2 (and more appropriately LN2) is to purchase it from a source that will provide you the correct "food grade" containment vessel rather than just going to any old gas supplier where the containment and handling procedures can introduce potentially dangerous contaminents.
as91 year ago
Where do you get LN2????? And what's the safest way to use it???
makendo (author)  as91 year ago
See step 1. See intro. But don't splash it around like you do question marks... :)
Great instructable! :) But...
*...where does one get Liq Nitrogen from?
* Who sells it in UK?
* How much does it cost?
* How long does it last?
* How long can we store it?
* Where do we store it... in freezer?
* If splashed with it, do we immediately rinse off under tap water?
* How long is exposure before we start losing fingers? ;)

Thanks
makendo (author)  MicroKID1 year ago
The main barrier to use is getting a dewar for storage and transportation. They're expensive and you're unlikely to be lent one unless you've been trained in the handling of LN2. How long it lasts depends on the quality of the insulation; a good stainless steel thermos flask filled with LN2 will still contain most of the LN2 after leaving overnight. If you're splashed with it, the Leidenfrost effect means it boils instantly and it will just tingle. I doubt you could immerse your hand in it for more than a few seconds without receiving a serious cold burn. Do not store in the freezer; that's like trying to keep an ice cube cold by putting it in the oven.
jvector1 year ago
Looks amazing but I am concerned: no mention of protective gloves or eyewear? And it looks as if there are kids participating? Fantastic fun for them no doubt but are all safety issues fully addressed here?
makendo (author)  jvector1 year ago
I appreciate your concern. The kids ate the ice cream but didn't make their own. I had eye protection on when dispensing the LN2 into the polystyrene container (which is not a detonation hazard). As for gloves; a splash of LN2 is much safer than a splash of boiling water, thanks to the Leidenfrost effect, so making ice creams this way is less dangerous than a more conventional activity like stirring a boiling pot of water or enjoying a fondue.
jcook201 year ago
Contaminated LN2 would be more useless for the original intended purpose of non-oxidising cooling than for chilling food. As everyone else has implied, the gasses tend to be highly pure or it becomes a real safety issue in more contexts than eating.
manan31 year ago
Whoa idiots like me are gonna find this a bit risky but its so cool :)
iceng1 year ago
Neat ible with great descriptive pictures !

Where did you get your dewar ?
makendo (author)  iceng1 year ago
Thanks.
I borrowed it from work; it originally came from VWR, a scientific equipment vendor.
What a fun way to do liquid nitrogen ice cream!