Trolley problem???

The store shouldn't be involved as nothing was stolen from them. Your friend should have handed the item into their local Police office as lost / found property and they would hold it until claimed by the original owner within 28 days. Your friend may have the right to hold on to the items after reporting (depending on local police policy), subject to the Police ping on their details to anyone reporting them lost, but would not "own" them until the 28 day period had ped. Not very practical for food I know, maybe they could freeze them