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Dry ice ice cream


TienYin
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Hi,

I work in a lab and we're always getting shipments with dry ice. I was wondering if I could use this for making ice cream. Two major concerns:

1) I see that I can use the dry ice to make a cold bath with denatured alcohol. I like this method since the dry ice never comes in contact with the food. Is the liquid necessary? Will I get insufficient cooling if I pack the cooling core (in my case a pot) with just dry ice?

2) How food safe is the dry ice? I see some recipes involve adding the dry ice directly to the liquid to produce carbonated ice cream. How do you know if dry ice is food safe? (It wasn't packed with anything hazardous). Also, how do you know if liquid nitrogen is food safe?

Thank you.

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Most (if not all) dry ice is food safe as it's just frozen CO2. There's no real danger from adding it directly to food stuffs as long as the items being shipped to you in the dry ice aren't dangerous. If you're getting ecoli samples sent to you packed in dry ice, I would just throw it away though. :wink:

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I'm more worried about the handling of the dry ice from when it was produced to when it gets to me. Since it's never meant to be clean, I don't know what contaminants could be in there. I feel good about the liqN since it's produced and delivered in a sealed container.

Maybe I will give it a try anyways. A bubbly lemon sorbet sure sounds like fun. What's the harm of a few chemicals?

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I still wouldn't worry about that - the very nature of dry ice renders any contamination by other chemicals/outside detritus moot. It's so cold that it will kill most microbial contaminants, and if you're worried about dirt simply allow the surface to transpire before using it.

I do a lot with dry ice in the theatre, and have used it with no problems at all in cooking (particularly icecream and cocktails). I get mine from a chemical supply house that receives it in turn with shipments of volatile chems.

Elizabeth Campbell, baking 10,000 feet up at 1° South latitude.

My eG Food Blog (2011)My eG Foodblog (2012)

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I would imagine that the alcohol bath would be absolutely necessary for efficient heat transfer. I'm not one of the physical chemists that seem to be floating around here, but even with regular ice and a metal bowl, having a bit of water for the bath seems to make all the difference when I am trying to chill something down quickly. The dry ice I have seen used all looks like extruded rods, and would make contact with a vessel irregular with a lot of space between relatively small points of actual contact. Just an observation and guess, with no rigor at all, for what that's worth.

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Dexter is bang-on about needing a liquid if you're using dry ice in your ice-cream maker, but if you're adding it directly the alcohol would do funny things to the recipe....

Liquid nitrogen is also food-safe, but I can't imagine any recipe that would work with it, beyond cryogenically preserving interesting edibles.

Elizabeth Campbell, baking 10,000 feet up at 1° South latitude.

My eG Food Blog (2011)My eG Foodblog (2012)

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Dexter is bang-on about needing a liquid if you're using dry ice in your ice-cream maker, but if you're adding it directly the alcohol would do funny things to the recipe....

Liquid nitrogen is also food-safe, but I can't imagine any recipe that would work with it, beyond cryogenically preserving interesting edibles.

It is fairly common now for people to make ice cream using liquid nitrogen and a stand mixer - there is significant discussion of it in Modernist Cuisine.

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I've done dry ice ice cream both with dry ice directly in the bowl, and in a bath of denatured alcohol. The difference comes down to whether you want your ice cream carbonated or not.

If doing the direct method, I recommend looking at the dry ice first (mine came in big blocks) - if it's pure white, it's fine, otherwise if you see any dirt, just scrape it off. Then break into chunks and throw in the food processor just before addintg to the ice cream - you can get a much more even distribution that way and guarantee that there are no big chunks for someone to potentially bite down on and frostbite their tongue.

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Well, BMDaniel, I still make my ice cream in a copper bowl, spinning over a bed of ice (dry or otherwise) and water - they make an ice-cream attachment for stand mixters?

You can make liquid nitrogen ice cream with just a spoon and a metal bowl - no stand mixer needed, although I'm sure the texture is better that way. I assume if you are making it in a stand mixer you just use the regular bowl and paddle attachment, then slowly add liquid nitrogen until you get the consistency you're aiming for.

They do also make a canister style ice-cream attachment for stand mixers - it's the type that you pre-freeze in a deep freeze.

Tammy's Tastings

Creating unique food and drink experiences

eGullet Foodblogs #1 and #2
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1) I see that I can use the dry ice to make a cold bath with denatured alcohol. I like this method since the dry ice never comes in contact with the food. Is the liquid necessary? Will I get insufficient cooling if I pack the cooling core (in my case a pot) with just dry ice?

We just did a side-by-side ice cream test using LN2 added straight into the cream mix versus a double-boiler method (I also work in a lab), and we've made little cold baths with CO2 for cooling other foods. I think the results are applicable to your question - the two ice cream batches progressed almost identically, except that the mix in the cold bath took a few minutes before it started to solidify, whereas the other started to harden immediately. The temp transfer will be more even if you use liquid, but there's no need to use denatured alcohol - ethanol works fine. Isopropanol, too (don't use methanol...). If you decide to go dry, smaller CO2 chunks will work better than big pieces chipped of a block. If you have those little jellybean-sized pellets, maybe you don't need the liquid.

You could also use water, but 1) you'll get a huge plume of steam when you first add it as it will immediately melt a portion of the dry ice and 2) it will freeze solid within a minute, so get your empty bowl pushed into the steaming mass right away and make sure to add enough water the first time.

Let us know what you do and how it goes!

Edited by MellaMella (log)
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I did try this out. Luckily, the dry ice was very fine, almost like crushed ice. Heat transfer wasn't really a big problem since I was stirring it by hand (it was at work so my resources were rather limited). In fact, the major problem was that it became too hard to scrape the frozen ice cream off the sides and incorporate it well. I eventually ended up with a bowl of really hard ice cream with a soft centre. The texture evened out nicely after I let it sit at room temperature for awhile. Since I was stirring the whole time, the consistency was rather good, even in the solid parts. All in all, it works well but could be improved with an electric mixer. It was a lot more work than liquid nitrogen though.

As for mixing it in, I wouldn't be so sure it's pathogen free. bacteria are hardy little buggers, we've had e coli survive the -80 without glycerol and fungal spores are probably still viable. I'm still mostly worried about chemical contamination though, I wonder how it's stored. Does transpiration do any good? Doesn't the contamination just keep settling down onto the dry ice under it?

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Hmmm what temperature does the dry ice-water mixture end up as? It might be useful to chill the cream a bit more slowly so that I don't form that impenetrable ice cream shell.

I may sneak in on the weekend with a hand mixer and try the liquid double boiler method. That way, no one will ask why I need 500 ml of alcohol and what that noise is. . . and if I get caught maybe I can buy their silence with ice cream.

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I'm with you, regarding pathogens. Unless I was getting it from a food supplier, I wouldn't trust it; there's always considerable and gross residue in whatever container I use CO2 in, and cells and bacteria survive immersion in the liquid phase of LN2 with no difficulty!

Regarding the temp - CO2 is ~-110. You might also try salt water, like back in the day :) I don't know how much salt it would take to keep the water liquid, although I suppose it could be calculated if someone was bored... Maybe spritz the inner bowl with alcohol, if you have little squirters around - might get just a little wet layer?

Edited by MellaMella (log)
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  • 2 months later...

Hi, I'm only a high school student- but you might want to stick to alcohol. According to some quick calculations (from what I remember from last year's chem class) with some margin built in- it'd take over a kilo of salt in a kilo of water; i don't remember water's solubility curve- but I'm pretty sure you can't do a 50-50 solution. C02 is more readily available to me than N2 but carbonated ice cream is pretty darn far from desirable in most of my applications. I'm open to cheap double boiler ideas. I've got a copper/glass one, but superchilled glass doesn't sound like a super idea to me. What would be really awesome would be container that could move from a super chilled bath to freezer and be agitated via mechanical means. Any ideas???

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Hey BB,

We did it this past week with CO2 and ethanol, but realized after starting that isopropanol was what we should have used (iso gets thick and syrupy when cold, eth just bubbles off). It worked, but maybe I should clarify - because dry CO2 can be filthy, we never considered adding it directly to the dairy, but used a metal bowl to hold the dairy, a plastic bucket to hold the cold mixture and nested one inside the other. No carbonated cream for us! The consistency wasn't as gorgeous as with LN2, but we were working with what we had (it was a hot day; ice cream was required.) I've read on various blogs that it's easy to do LN2 at home in a regular stand mixer (also see tammylc and bmdaniel above), you just have to add a very slow stream (in which case, you're adding directly to the dairy; you also need to own a dewer, and LN2 sounds like it's easy to get at restaurant suppliers). I imagine adding it too quickly would cause the motor to seize.

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The killer property of dry is that it will carbonate your ice cream. Think about the possibilities ... I've come up with a champagne sorbet that's actually bubbly. The catch is that the carbonation dissipates. Unless you have some kind of pressurized ice cream carton (I don't) it will keep it's bubbles for 24 hours at most, and the fizz will dissipate steadily from the moment it's frozen.

Best to crush the dry ice in a blender or food processor before using. The procedure is the same as LN2, but you're working with a solid.

Notes from the underbelly

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Co2 ice cream is interesting, just not what one might want to eat with everything all the time. The cold bath seems like where it's at and would be much easier for me (the home cook) as dry ice is a trip to the super market down the street as opposed to renting a dewar etc. How long does the base take to freeze this way? And did the alcohol bubble of completely?

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Co2 ice cream is interesting, just not what one might want to eat with everything all the time. The cold bath seems like where it's at and would be much easier for me (the home cook) as dry ice is a trip to the super market down the street as opposed to renting a dewar etc. How long does the base take to freeze this way? And did the alcohol bubble of completely?

There's no need for alcohol. The dry ice is added directly to the ice cream base. It evaporates as the ice cream freezes. A small percentage of the C02 goes into solution in the water in the base, carbonating it, where it will stick around for several hours, gradually diminishing.

There are other ways to use dry ice that won't carbonate the ice cream, but I don't see the point. There are much easier and more economical ways to make ice cream.

Keep in mind that while dry ice is very cold, it does not have an especially high specific heat. The cooling potential for a pound of dry ice may actually be less than the cooling potential of a pound of water ice, in terms of the number of calories it can remove. It's probably much less compared with the fluid that's in ice cream machine canisters. So you will need lots of it.

Notes from the underbelly

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  • 2 weeks later...

Paul, I agree.

I wanted to be sure though so I ran a couple tests:a method posted on this site (wrapping the bowl in an ice-filled plastic bag) didn't work. The alcohol bath, didn't work- and got alcohol in my ice cream (not so happy about that one), and dumping straight dry ice (started with carbonation, again interesting but not desired in this application) but somebody mentioned the creation of carbonic acid and I think that's the funny flavor I kept tasting. On the upside, it didn't take that much dry ice. I retreat to the freezer bowls with ice cream scoop between my legs unless somebody knows of a N2 distributor in SoFla

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