The Order regarded the sick and poor of all religions as if they were Christ himself, and no luxury was denied to them. This included providing white bread, a rare luxury in the medieval period, which was baked solely for hospital patients. This bread stamp would have been pressed into fresh bread, leaving the eight pointed cross of the Order imbedded.
Foakes, Tom, ed. Treasures: Faith, Care, Valour: Highlights from the Collection of the Museum of the Order of St John. Priory of England and the Islands of the Most Venerable Order of the Hospital of St John of Jerusalem, 2019. Pages 102 - 103