I've been doing this for a couple of years. Take a jar with a good lid and fill it with HOT water. Dissolve as much non-iodized salt in the jar was as possible. Rinse the outside of the jar to clean any salt off. Place it in the freezer overnight. It will not freeze because of the salt. Put your leftover bait in the jar in the freezer. The cold water preserves the smell and the salt cures it. The next time you go fishing you will have bait that is cured but still smells fresh. The down side is that any water that is spilled in the freezer makes a mess.