Great question — answering as the UphillTech team:
Once fried chicken or any fried food for that matter is refrigerated it is going to lose its crispiness. This is due to the crunchy exterior coating absorbing moisture from inside the food, combined with moisture being trapped inside the wrapping/storage container which then is absorbed by the food as well. It happens even shortly after frying if the food item is placed on a flat surface where the inner steam can't escape and is trapped between the food and the surface under it. This is why when frying large batches or holding fried food for any extended time, it's best to drain on a cooling rack that's upside down on a brown paper bag or paper towels. Upside down so that it's close to the...
Full answer by Darin Sehnert: https://cooking.stackexchange.com/a/3892 (CC BY-SA 3.0).
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