Confirmation of United's retained and released lists revealed 15 out of contract players will exit the club this summer.
Mata has been offered a new contract, but is still to make a decision on his future.
At Under-23s level, the club has taken up the option to extend midfielder Aidan Barlow's deal. Fresh terms have also been offered to keepers Alex Fojticek and Paul Woolston, plus Italian defender Luca Ercolani.
Several players who spent time away from the club on loan last term will be seeking deals with new teams as they continue their careers elsewhere. Regan Poole helped Newport County reach the League Two play-off final, while Zak Dearnley (Oldham Athletic), Tom Sang (AFC Fylde), Callum Whelan (Port Vale), Matty Willock (Crawley Town) and Wilson (Aberdeen) also had loans away from Old Trafford.
Matthew Olosunde, Tyrell Warren, DJ Buffonge, Callum Gribbin, Millen Baars and Josh Bohui have also been released, as has Under-18s goalkeeper James Thompson.