I’ve won the battle and now I plan to win the war.
Now that Ben and Jerry’s Wavy Gravy is officially back for ‘a limited time’ I hope to stock up on enough of it while it’s available so that I can snack on it well into the future.
I know from experience with crystal coated gummy old ice cream that the paper containers they come in are too porous to be effective in long term storage in my freezer as is. Is there a method or recommendation on how to store ice cream for long periods?
The other big factor beside containers is freezer temperature. If your freezer is above -18°C, or it has a defrost cycle, you’ll encourage ice crystal formation. Ideally for long term storage, you’d want a -70°C freezer. When you get something that cold, there’s a lot less crystal reformation, and even sugar epimerization slows to a crawl.
According the McGee’s On Food and Cooking, ice-cream never freezes fully in a commercial fridge. As the water freezes, the sugar solution becomes more and more concentrated which loves the freezing point of the remaining sugar solution. For it to fully freeze, you would need to lower the temperature enough to freeze it fully. Of the top of my head, I don’t know how low you would have to go but theres some stuff on the science behind it here. However, I would assume that liquid nitrogen would do a good job relatively cheaply.
However, it is possible to stabilise ice-cream at relatively low temperatures if you understand what’s going on. It’s not high temperature that’s detrimental to ice-cream so much as variation in temperature. If the temperature rises, smaller ice-crystals dissolve and then reform onto bigger crystals when the temperature drops again. If you can find a method of keeping a freezer at a remarkably stable temperature, then crystal production would be slowed down dramatically.
Alternatively, theres no real chemical changes going on in ice-cream as it ages, just physical. Which means that it should in theory be possible to melt and then refreeze the icecream again. How to recreate the wavyness is an exercise left up to the reader.
Just send it over here. I’ll store it…oh…never mind.
The ice crystals that form on top of the ice cream after you open it are from moisture in the air condensing and freezing on the ice cream. It doesn’t matter how cold your freezer is. I work with -80 degree Celsius freezers without defrost cycles, and they build up frost just like any other. I wonder if including a dessicant in the freezer compartment could help? Alternatively, you could try pumping in some compressed inert gas to cover the ice cream. Ok, those options are a little extreme.
Perhaps a large airtight container could be used to store all your ice cream inside the freezer? I’ve found that simply placing it in a ziploc bag seems to help keep it longer. Another recomendation to avoid frostbite is to place Saran Wrap directly on the surface of the remaining ice cream.
My initial thoughts are to bring some kind of metal or hard plastic container to the scoop shop have them fill it (reduction in porous nature of the packaging). I’ll then try to store it in either an old freezer without defrosting equipment (reduction in temp variation) or the deep freeze here at the cafeteria at work (lower temp).
The only issue I see is that I’d have to take a band saw to the giant lump to carve off a chunk for eating.
Perhaps using one of those food saver type things and tossing in a pint or quart in each bag?
This is not entirely correct. You could put the ice cream in an airtight bag (a loose one) and still see those crystals. Those crystals are from the moisture in the ice cream migrating towards the container. This phenomenon is commonly known as freezer burn. It is particularly notable in meat. I am not knowledgable of the chemistry behind this but I believe it is related to sublimation.
Airtight containers that seal against the surface of the food can indeed help this. The moisture can’t migrate out.
I have a FoodSaver machine which seals food in a plastic bag by sucking out all the air. It works great and I never get freezer burn.
My WAG. You could have the Ben & Jerry’s vacuum-sealed. Put it in a freezer that can maintain a temperature below - 70 °C. Then you could maintain liquid nitrogen in the freezer. Though someone is going to have to check me on that because I don’t know if it is feasable or safe. Dry ice might be able to say “dry” at a certain temperature and you would not need to replace it.
CookingWithGas, I just noticed your post about the FoodSaver. I was wondering where I got that idea. Do you know if it is feasable or safe to use liquid nitro and/or dry ice?
One way to minimize the ice cream’s temperature variation would be to wrap it in some kind of insulation, after putting it in an airtight container or bag. Just a cardboard box, packed in with crumpled newspaper might help.
Yes and no. The temperature flucuation is an important factor, but there are chemical problems with long-term storage. Ice cream is wet, your freezer is not. Moisture will migrate from the ice cream to the freezer. You can minimize this with reduction of headspace and more air-tight packaging as previously mentioned. But you will still have a shelf life problem. And plastic film is not as good as insulating as cardboard, so you increase your freeze-thaw fluctuations. I am not familiar with wavy gravy, but I assume that there is some sort of ripple of gooey goodness in it. The gooey goodness, or mixed in chocolates, candies, nuts, etc. will either be more or less moist than the ice cream. Your moisture will redistribute making ice crystals, sugar crystals, dissolving candies, etc. depending on the mixed-in ingredients. Finally, there is lots of fat in ice cream (I hope you knew that). Fat loves to go rancid. At freezer temperatures, that happens much slower than at room temperature, but dairy fats are very prone to rancidity. That is usually the ‘old’ flavor that ice cream gets. Again, vapor-proof packaging, headspace reduction, and protection from freeze-thaw cycles will help, but only so much. Plan on eating your stash within 3-6 months even with the best of storage conditions.
I don’t know with any authority. Dry ice, of course, is used for all sorts of food applications, like ice cream carts. Dry ice is frozen CO[sub]2[/sub], which is toxic in large gaseous quantities. It hugs the ground, so don’t lie on the floor in a room where dry ice is exposed. When it sublimates the pressure will go up, so you don’t want to put it in a sealed freezer. The pressure will build until the door blows open (or off).
Liquid nitro I know less about. It’s colder than dry ice. It will also evaporate and displace breathable air, probably would also cause a pressure issue in a closed container above 320ºF, its boiling point. Coincidentally I was reading a gourmet cooking magazine last night that has an article about industrial devices used by some chefs. One guy uses a tank of liquid nitro to dip some types of food in for quick and decisive freezing. So it apparently can be used safely in food preparation. (I remember one demo I saw on TV as a kid where a TV scientist dipped a carnation in liquid nitro for a second then broke it on the table–it shattered like glass.)
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Well, there is one way to enjoy your ice cream for many years to come. Have you ever had NASA ice cream? It literally melts in your mouth. It is freeze dried so there will be no problems with moisture or fat going bad. It’s dry ice cream!
Have your Ben & Jerry’s freeze dried and then vacuum sealed. Then insulate it in a good freezer and you’re all set. 
Is this something I could have done? That would be awesome. I did a couple of google searches and I’m getting nowhere.