Freeze them for just a day and they will revive. Paste paul is bang on with his idea of keeping maggots in a bag. It's by far the best way to keep them for any length of time. In the same theme, I keep my maggots or casters in a pellet pump, it keeps them fresher longer just like bagging them. With a pump or in the fridge to obtain their freshness just give the maggots or casters a few minutes fresh air daily.
The fridge for me is an outdated way of saving fresh bait, OK they will last longer Pp is correct again with skins toughening. Pinkies, for example, will last it seems forever in the fridge but the tough skins are a recipe for fewer bites.
I know you'll get bites on fridged bait but more bites with fish holding on seem far better.