Keeping Ice Cream Cold
June 30, 2004 1:50 PM   Subscribe

4thOfJulyFilter: I want to be a superhero and bust out some ice cream bars during our 4th of July car camping trip this weekend. If I pack them in dry ice in a cooler on Friday night, will the dry ice last til Sunday afternoon and will it be cold enough to keep the ice cream frozen? (It'll be in the mid 80's at the hottest where I'm going.) Is it OK if the cooler is a cheap styrofoam one (since my good cooler will be filled with beer and BBQ fodder)? Is there a better way I could be attempting this?
posted by badstone to Food & Drink (19 answers total)
A slab of dry ice, depending on its size, might struggle to last that long but it's merely a matter of buying enough of the stuff and having some decent insulation. I've had mail-order chow shipped in a dry ice/styrofoam rig, and managed to eke out a couple of extra days of coldness beyond the shipping time.

You'll get more use out of a portable freezer, though. How's the battery in the car?
posted by majick at 1:58 PM on June 30, 2004

Getting some conflicting reports, but this search indicates that you'll need about 15 pounds of dry ice.

Anecdotally, I've found that the cheap-o styrofoam coolers work really well.
posted by trharlan at 1:58 PM on June 30, 2004

It should definitely be cold enough. Regarding longetivity, my experience with dry ice and coolers is as long as you keep the cooler closed, it'll last a few days just fine (some will sublime away, but a good enough chunk should still be present to keep it cool). I've always dealt with ~10-15 Lb blocks, to give you an idea, but always with a real cooler.

Just be careful when handling the dry ice; wear thick gloves. As a treat, leftover dry ice can be thrown into some water for fun (bonus points if the water is boiling or hotter than normal temp)... just be cautious with it.
posted by thebabelfish at 2:00 PM on June 30, 2004

As Majick said, mini car refrigerators (the fridges are cheaper than the full-on freezers, and should work if you set them on high and maybe supplement with a little dry ice). Most truck stops carry them, if you don't want to wait for mail order.
posted by milovoo at 2:07 PM on June 30, 2004

I'm no expert, but milovoo's advice is suspect.

Most refrigerators have a thermostat, and will only kick on if the interior temperature is above a certain point. To reach that point, the dry ice has to be gone (or nearly so).

It's not like the fridge and the dry ice will "team up" for extra coldness.

Like I said, I'm not an expert, and I welcome corrections.
posted by trharlan at 2:33 PM on June 30, 2004

Should be fine, if you use enough dry ice. I routinely store a 20 kg bag of dry ice in a cooler (sample transport). It lasts about 4-5 days. By the way, a single block lasts much longer than broken (or chunk) dry ice. Twenty kilograms costs us about $17 Canadian, about 13 bucks US.

I've always liked taking freeze-dried ice cream on camping trips. It's not at all the same as ice cream, but no one has ever said no to a bar either. It's sold in camping stores.
posted by bonehead at 2:33 PM on June 30, 2004

more stuff after I hit post:

* styrofoam works great, but plastic coolers ar only about twice as much.

* don't open the cooler until you need the ice cream. Keep it out of the direct sun if possible.

* use winter gloves or oven mits to handle the dry ice. Never touch it with bare skin.
posted by bonehead at 2:37 PM on June 30, 2004

Good point trharlan, that is probably true for most of them, although it looks like the peltier pump based ones do not have a thermostat, and they list the temp not as a fixed number but as 20?-25? below ambient, so perhaps ... ?
posted by milovoo at 2:43 PM on June 30, 2004

Uhhh FWIW - remember dry ice is solid CO2 - while it's melting it may "pop" the top off a Styrofoam cooler. So you may want to put a weight on it. Any one experiences this, as I was about to suggest taping the lid's edges for a better seal. Then realized the potential consequences of dry ice melting in a closed Styrofoam container for 3 plus days.
posted by thomcatspike at 3:00 PM on June 30, 2004

whoa! thomcatspike has a great point! I was in fact thinking I would just duct tape the cooler shut until needed. do styrofoam coolers "breathe"? that is, would the gaseous CO2 work its way out through the porous styrofoam? do I need to build some sort of pressure release valve into this system?

re: the mini-freezers and such - that is a bit beyond my means and need. If I can make this happen for under $20, it's worth it to me, otherwise, there're other ways to have good, cheap fun on the 4th.
posted by badstone at 3:23 PM on June 30, 2004

badstone, you could "burp" it every day.
Recall that as dry ice melts, the moisture in the air will form a layer of ice around it insulating the CO2.
posted by thomcatspike at 3:45 PM on June 30, 2004

Yeah, you really don't want to seal it tight---dry ice can split styrofoam if left sealed too long. Regular coolers (plastic or styrofoam) have bad enough seals that it doesn't matter, but don't go taping it shut!
posted by bonehead at 3:50 PM on June 30, 2004

styrofoam is one of the main ways people transport dry ice. when i worked in a genetics lab, we were using it all the time, and i used to scoop chunks out of a huge plastic tub into a styrofoam cooler.

hmm. i didn't need it to stay in there too long, however... bonehead has some salient points. and thomcatspike has a good point that water will freeze around the dry should make sure that your cooler has some breathing room or something. or "burp" it.
posted by taumeson at 5:44 PM on June 30, 2004

A few years back, through the kindness of a far-flung relative, we received some Omaha Steaks for Christmas.

They arrived in a large styrofoam cooler which had been shrink-wrapped, so I don't know how much you should worry about the tape causing massive CO2 explosions in your car. Our package had been sealed for two days (we didn't know it was coming); when we opened it, the steaks were rock-solid and there was no obvious venting of pent-up gas.
posted by baltimore at 4:39 AM on July 1, 2004

Coleman sells and extreme cooler for $50 that will keep ice for three days. Might want to see what it can do with dry ice.
posted by mecran01 at 6:35 AM on July 1, 2004

thanks all!
posted by badstone at 8:59 AM on July 1, 2004

On a related note...where do you buy dry ice?
posted by gimonca at 9:15 AM on July 1, 2004

Ask at a grocery store. The two nearest supermarkets in my town will gladly sell dry ice at reasonable if not bargain prices.
posted by majick at 10:00 AM on July 1, 2004

I've stored it in styro, plastic, and old-time metal coolers with duct tape around them loads of times and they've never exploded. Further, if you do this, the ice cream will easily last Friday->Sunday. The problem will be that it's too cold. You're gonna end up with super-frozen rocks of ice cream. That's the tricky/annoying part.

I've put orange juice containers in duct-taped coolers with dry ice and opened them 6+ days later and had the juice be frozen.

My girlfriend once sent me ice cream packed in a styro cooler with dry ice (overnight). It took hours before the ice cream was edible. Also, the extreme cold made the labels peel off the containers and made them really brittle. In handling, a couple developed thin cracks that turned into ice cream leaks. Other than that, it worked great.
posted by jeb at 1:55 PM on July 1, 2004

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