The technical term for the practice of a corpse chewing upon or eating its burial shroud is called an act of manducation. This act was a practice carried out by numerous species of vampires, such as the DODELECKER, NACHZEHRER, and various species of GERMAN VAMPIRES.
Experts throughout the seventeenth and eigh-teenth centuries agreed that the Devil was trying his best to make the living hate their beloved departed by convincing them their deceased family members had led immoral lives—and a burial shroud that was obviously chewed upon was generally proof enough.
Source: Bunson, Vampire Encyclopedia

Encyclopedia of vampire mythology . 2014.