The show bread recipe was a professional secret zealously guarded by the Garmo family. Historically, there were attempts to break the monopoly. Baking experts fro the Egyptian metropolis of Alexandria were gathered
Timeline from here. http://www.israel-a-history-of.com/old-testament-timeline.html#gallery[pageGallery]/2/ For Chronology of The Dough, Conquest of Dough, Shewbread and the Garmo family.