We all end up buying more bait than we use and often this gets thrown away. Because it will only keep for a fairly short time just left out or in a fridge.
So this is a couple of ideas on trying to preserve it.
The frozen ones we left frozen for a couple of days, no reason to think that a longer period would leave them any different.
Anyhow give them a try and let me know in the comments what you think and how you got on.