How can I get soft serve from SF to LA by car without ruining it?
April 4, 2021 11:28 PM   Subscribe

This may be a fool's errand but it's worth a shot. A friend's favorite ice cream is at Milk Cow in the bay area. They live in LA. IS there any way to put it in a cooler and keep it for five or so hours for the drive? Crazy ideas welcomed.
posted by rileyray3000 to Travel & Transportation (17 answers total) 1 user marked this as a favorite
I don't think this will work--barring any really clever ideas coming up--but I actually think the best hope is a simple cooler. Make sure you have plenty of ice but also a decent amount of liquid water. My reasoning is this should keep it right at zero degrees C, so if you put it in cold you might not get fast crystal growth and it also might not melt.

If you want to hedge your bets, get two containers, seal one tightly and don't close the other. Because moisture content in the air might make a difference, though I don't know which direction.

This is an interesting question and please report results if you try it!
posted by mark k at 11:39 PM on April 4, 2021 [1 favorite]

I once took a milkshake to a dear person a 90 minute drive away. It was in a not quite sealed ice-filled cooler and it held up, so I think this should be possible.

Jeni's ships their wonderful ice cream in a setup that's more or less a cardboard box with a styrofoam cooler and dry ice inside, and it arrives at my door hard as a rock. It looks like Milk Cow is soft serve? Have them put it in a plastic Gladware container or similar, seal it up, put it in the cooler and box and a little chunk of dry ice. It might actually get a bit too hard in transit, but a few minutes at room temperature would fix that. It won't be perfect, but I bet it would work.

Also, it looks like there are Milk Cow franchises in LA? So that would be the easiest option.
posted by mostlymartha at 12:17 AM on April 5, 2021

According to UPS if you want to ship ice cream you should use dry ice or gel packs. Note that they are assuming regular ice cream and not soft serve, which in my experience undergoes a change if it gets frozen. For that reason, the gel packs might be a better choice than the dry ice since that will probably freeze it solid.
posted by forbiddencabinet at 12:22 AM on April 5, 2021

Get a block of dry ice and a good cooler. Dry ice is compressed CO2, much colder than ice cream, and takes a long time to sublimate. A 5 or 10-pound block will take 12-24 hours to disappear. (Depends on size and conditions.) Put the ice on top of the ice cream. (Heat rises, cold falls.)

Important safety notes:

- Dry ice is really cold. Way colder than anything you have touched before. In solid form, it's -109F or lower. Do not ever handle dry ice with bare hands. It will burn you. Use a pair of work gloves.
- Keep a window cracked. The sublimation of the ice produces CO2 in gaseous form.
posted by secret about box at 12:23 AM on April 5, 2021 [3 favorites]

It looks like Milk Cow is soft serve?

Oh, hmm. I don't know how soft-serve would react to being in a box with dry ice for five hours. I know you can make soft-serve with dry ice, but I dunno about transporting it that way.
posted by secret about box at 12:27 AM on April 5, 2021

Ice and rock salt in a cooler would probably do the trick, and it would have less chance of freezing it hard than dry ice if the ice cream is soft serve.
posted by jamjam at 1:59 AM on April 5, 2021

I don't know if dry ice will work for this but if you do decide to use it there's one or two things you should know about shipping. Dry ice has to be shipped in a vented container. If you're going to do it right, you will need to put the proper labels on the box. For Fedex it's something like. Don't forget to put the weight of the dry ice on the label. You should probably put orientation arrows on the box also.
posted by rdr at 2:02 AM on April 5, 2021 [1 favorite]

(Just checking that you’re aware that there is a Milk Cow branch in LA... they’re all franchises, so should have very similar menus. But perhaps there is a reason to go for the one further away, in which case please disregard.)
posted by whitewall at 2:38 AM on April 5, 2021 [3 favorites]

I’ve done this in winter a couple of times on the East coast and it was hard to keep the ice cream from melting buttttt...I will say it can be done. If you stocked the cooler full of ice and then stopped for more ice at a coffee shop, or supplemented with those insta cold pack bags that you get at a drug store perhaps it would get it there in acceptable condition.
Oh, wait...soft serve? At best you’d have to freeze it at home first and then transport it. It’s not going to hold up the same texture wise. In any event, you’re a good friend!
posted by Champagne Supernova at 3:36 AM on April 5, 2021

Some research shows that the ideal temp for soft serve is 18 F (below freezing, but not too much below). Ice alone cannot go below 32 F (much). Too much ice in the softserve and it tastes like rock. To little ice and it's just sweet sludge. So over-doing it with dry ice would be just as bad.

Cooler doesn't have the cold capacity, even with a lot of ice, to preserve that 18F temp. If you are going by vehicle, the only way this will work is a mini freezer (like the ones sold to long-haul truckers), and you need to adjust and calibrate the temp for at least a day before attempting it. Probably too much trouble for "just a favor". So add the cost of a thermocouple. :)
posted by kschang at 6:55 AM on April 5, 2021 [1 favorite]

Some background on temperature control with ice. Totally skippable if you know all about melting temperatures already:

Dry ice is solid up to -78 C. Normal ice is solid until 0 C.

It takes a lot of energy to phase transition (solid->gas or solid->liquid) so a pile of dry ice below -78 C will heat up to that temperature, but then stay at that temp and just get smaller and smaller. Same with water ice, which stays at 0 C, and stops heating up until it melts. You use dry ice for long term shipping because it will start colder and therefore keep things cold longer. This means that a cooler will be guaranteed to be at max 0 C or -78 C, depending on the ice you use, until the ice is all gone. It should certainly last a five hour trip.

If a cooler equilibrated perfectly, if you mixed dry ice and water ice the cooler would drop to -78 C if you put in enough dry ice to stay solid. In practice you can put in some on the bottom, with water ice above it, to try and keep the whole thing cooler longer. It can also make it colder than 0 C, but not stable. It will either be slowly warming or cooling, depending if you have dry ice left.

The rock salt idea is interesting. It would melt some ice but the resulting ice/brine mixture is below zero. It will slowly warm up from whatever you start at, somewhat more steadily than a pure ice-packed cooler.

To keep the soft serve soft you are trying to keep the water from crystallizing. I'm sure too cold is worse than too warm--it happens in a normal freezer (which is around -18 C). Based on kschang's comment I think you might have a shot if you keep it at zero. I don't think it will melt at that temperature.

Some bonus dry ice tips:
- Never put dry ice in a tightly sealed container. It will evaporate and explode the container. Extremely dangerous. (Arguably fun if you do it in small Eppendorf tubes as a lab prank, though really even if you get a good reaction after ten years you can really give it a rest and stop bringing it up at happy hour.)
- If you are working in a lab and having a picnic, don't fill the cooler for ice cream with dry ice just because it's around. The ice cream will get break-a-tooth hard and your tongue will freeze to it.
- If you are taking dry ice home for some reason, don't just put it in the back seat of a car. It will turn to CO2 and you'll start getting shortness of breath and hyperventilating.
- It's actually not that risky to pick up a piece of dry ice with bare hands as long as you don't squeeze it or keep it on the same piece of skin too long. It doesn't transfer the cold that quickly. OTOH don't be doing this so much that you lose respect for it, try it with wet hands, and have the dry ice freeze the water and stick to your hands.

posted by mark k at 7:52 AM on April 5, 2021 [3 favorites]

I am all for bad ideas and mad science, especially when it comes to ice cream, but I don't think this is going to work. I would try an experiment. Get a cone, take it home, and put it in the freezer for an hour. I bet when it comes out you are not going to like the texture. The mix in the soft serve machine is different than regular ice cream, specifically that the motion keeps the ice crystals small so it's creamy. Though you might be able to freeze it hard and then whip it in a blender to make a milkshake with the same flavor and acceptable texture. Keeping regular ice cream frozen for five hours is easy with a few hundred grams of dry ice on top of it in a small cooler.
posted by wnissen at 8:47 AM on April 5, 2021

FWIW, ice cream seems to be best kept at 0F, which is the default temp for most freezers in the US ( 0F ) Over freezing ice cream just results in freezer burn, which means crystals in the ice cream got solidified into a larger chunk, but usually only affects the "surface" of ice cream.
posted by kschang at 10:45 AM on April 5, 2021 [1 favorite]

My idea is to get an ice cream maker (something like this), fill up the container with your soft-serve ice cream, and then run it all the way from the store to the destination.

The idea is that by continually stirring the ice cream it will keep it cold yet still soft serve consistency. (Actually whether it would be exactly soft serve consistency is debatable, but it would at least but soft and not solid/hard.)

You can adjust the exact temperature of the ice by adding more or less salt.

This will require some way of running the ice cream maker motor while driving. This might be a bit tricky as I would imagine the motor requires a fairly high amount of amps, and most cigarette-lighter type power inverters don't deliver too many.
posted by flug at 12:47 PM on April 5, 2021 [1 favorite]

Multitask. Get the smallest cheap styrofoam cooler you can find at the grocery. Pick up a block of dry ice. Put the ice in the bottom, throw anything you *want* frozen along with it (maybe ice-pops for the trip). Fold up a towel or blanket to put on top of the dry ice and other freezer things. Put the just cold things on the top. Open occasionally on the trip to grab a bottle of tea or something.

You can adjust the relative temperatures like this. Thicker towel part, less cold bottom, thinner towel part colder bottom. Other cautions about dry ice stand.

I did this for several days when the fridge died. Opening for drinks/etc keeps the top from getting too cold (some lunch meat did just get a bit frozen in the top. The bottom is way cold. Block of dry ice lasts a good day. If you have one of those point-and-shoot IR thermometers or just a regular one I guess it might be easier to know if it's too warm/cold. Check the softserve when you get it, keep an eye on it's temp as you go.
posted by zengargoyle at 11:26 PM on April 5, 2021

Oh, what a delicious problem. You clearly need to experiment. You'll need to buy a cone a day, maybe more, store them for 10 hrs, and sample. Please publish your results. And just think of the peer review and replication!
posted by at at 2:25 PM on April 6, 2021

The old school lab tactic would be a dry ice-solvent slurry. Probably methanol-water-dry ice to keep your soft serve around -7 C.
posted by janell at 9:18 PM on May 1, 2021 [1 favorite]

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