When air drying frozen boilies you must make sure they thaw out in their bag completely first. There are two reasons for this, one is that they will dehydrate and the other is that the ice in the bag contains additives and nutrients that are re-absorbed during the thawing process.
The best way of air drying baits is to use a drying tray which are available from most tackle shops with instructions, but alternatively you can dry them on a towel in a warm, dry place, (an airing cupboard) or in a pillow case and hang it up. It is important to remember that the boilies must be shaken/moved about during the drying process otherwise mould could form. Never put too many boilies in at a time when drying to allow adequate air flow around the bait.
Tip from Richworth Baits