Dry Ice is frozen carbon dioxide — it’s -109 F (-78 Celsius.) It doesn’t melt; it dissipates as a gas.
When purchasing Dry Ice for use in or around food, make sure it is food grade. Food Grade Dry Ice (C02) is used for soda fountains, for transporting food in and even for making food. Food Grade Dry Ice is often used, for instance, in making Ground Beef. It’s crushed then incorporated into the ground meat to keep it cold while it is being processed. Because it’s not real ice, it doesn’t add water to the meat (which might increase the water ratio beyond what is legally allowed.)
If you haven’t specified Food Grade, your Dry Ice could have residual machine oil in it from the compressors that made it, which is fine for industrial and stage purposes.
At home, Dry Ice is mostly used in punch bowls, especially for Hallowe’en, where it creates a spooky effect par excellence. It will give punches a bit of a club soda feel to them in the mouth, though it won’t make them actually really fizzy. Mind that you protect whatever you place your punch bowl on: the Dry Ice is going to sink to the bottom of the bowl, and it could freeze the bowl to the table.
- Don’t break it up into small pieces. You do not want any Dry Ice to get into people’s glasses. You don’t want anyone swallowing it or handling it. That would be extremely dangerous;
- Have the punch bowl full of punch first. Add the Dry Ice as a large piece, but not too large, or it may freeze the contents of the entire bowl;
- Don’t add any regular ice; If you wish, you can add regular ice to people’s glasses;
- Expect it to sink to the bottom. This is normal. It won’t float. Towards the end, when it is finished giving off fog, it will be surrounded by real ice, which will buoy it back up to the surface. When it does this, there will still be some dry ice in this piece at the centre, so do not serve it;
Important Safety Rules:
- Never ever — ever — touch dry ice with unprotected hands. Within two seconds it will cause severe skin damage;
- Towels and oven gloves are not enough protection. You need to handle it either with special gloves certified for the purpose, or handle it with tongs;
- Never let anyone swallow or eat any dry ice, as it will cause severe internal injury;
- Never serve any dry ice in glasses;
- Never let children or intoxicated people play with it.
Store Dry Ice store in a portable cooling chest.
Do not store in a real freezer or refrigerator freezer. It must be stored in something that allows some of the gas it gives off to dissipate to avoid an explosion.
If the power goes out and you decide to use dry ice to keep the contents of your freezer frozen, you need to either be certain that your freezer is not airtight, or leave the door open a crack.
The discovery of dry ice is credited to Charles Thilorier in 1834. He had a canister of liquid carbon dioxide under pressure that he opened; it evaporated so quickly as the pressure escaped that it produced a chilling effect cause some frozen carbon dioxide to be left behind in the canister.
Commercial use of it started slowly in the 1920s in America; by the 1930s, it was being used to cool railway cars shipping produce across the country. After a short while, though, mechanical refrigeration came to be preferred.