Q: I’ll be driving to visit family about eight hours away, and I want to take some containers of freezer jam with me. Do I need to get dry ice to keep it cold in the car, or how else should I pack it? Where would I get dry ice?
Answer: In the first place, I would not recommend using dry ice in the car, and certainly not for a trip of that length. Dry ice is solid carbon dioxide. As it warms and evaporates, it gives off carbon dioxide. In a closed car that could be lethal.
If you were driving a truck and could keep it outside in the bed, you might be OK, but not inside the car.
Since the freezer jam is frozen already, it will be easier to transport that far. Well iced in a good, tight cooler should be enough. Put a layer of ice or frozen freezer packs in the bottom of the cooler. Lay in the containers of jam. If you have the space, ice or freezer packs between the containers would help. If the cooler is deep enough and/or you’re taking so much that you need two layers, put ice between the layers, too. Top the containers with more ice or freezer packs.
It won’t hurt them if they do soften slightly by the end of the trip. As much sugar as most jams contain, they’ll be safe for at least a couple of hours.
If you do decide at some point that you need dry ice, for example to keep a freezer safe when power is out, check around at your local grocery stores. Several have dry ice. Read the safety brochure, and do not touch dry ice with your bare hands.
Mary A. Keith, a licensed dietitian and health agent at Hillsborough County Extension, can be reached at firstname.lastname@example.org.