For now, it seems, they have all but forgotten. Industrial-scale baking and advanced freezing technology have made it possible for mass-produced loaves, rolls and pastries to be frozen and shipped around the country to supermarkets, where they can be heated up and sold for a fraction of the price of a hand-thrown equivalent from a traditional bakery.

The shift in culture is so worrying to bakers like Mr. Trefzger that they are taking extraordinary steps to raise the awareness of Germans, and the world, to the uniqueness of their threatened baking traditions. They are reaching out to young people via social media in an effort to attract more of them to the job. Last year, the German Bakers’ Association even applied for the country’s baking tradition to receive special recognition and protection by adding it to the Unesco list of cultural heritages, where it would gain a spot alongside French cuisine and Croatian gingerbread.

So far, however, none of those steps has reversed the seemingly inexorable decline of the German bakery. Last year, the number of German bakeries dropped 3.6 percent. Only 13,171 now remain in a country of about 80 million people that six decades ago counted more than 55,000 bakeries in the former West Germany alone. In the past seven years, the number of young people training to become bakers has dropped by a third, to 26,535 in 2013.

That is a long fall for German culinary tradition, more commonly associated with sausages, sauerkraut and potatoes. Yet from the days of Charlemagne until the end of the previous century, a staple of the German diet was thick, hearty slices of sourdough-leavened bread made from grains like rye or spelt. The German word for supper, “abendbrot,” means “evening bread.”

“Until the 1960s, bread served as the central source of nourishment in Germany,” said Peter Becker, president of the German Bakers’ Association. “People would even make a cross on the bread as a sign of thankfulness. That significance has been lost.”