A hobby historian has discovered the oldest known recipe for German sausage, a list of ingredients for Thuringian bratwurst nearly 600 years old.

According to the 1432 guidelines, Thuringian sausage makers had to use only the purest, unspoiled meat and were threatened with a fine of 24 pfennigs -- a day's wages -- if they did not, a spokesman for the German Bratwurst Museum said Wednesday.

Medieval town markets in Germany had committees charged with monitoring the quality of produce. Thuringian bratwursts, which are made of beef and pork, are symbols of Germany's cultural heritage and ubiquitous snacks at football matches.

Historian Hubert Erzmann, 75, found the ancient recipe, inscribed with pen and ink in a heavy tome of parchment, earlier this year while doing research in an archive in the eastern town of Weimar, museum spokesman Thomas Maeuer said.

"The discovery shows that there were already consumer protection laws in the Middle Ages," he said.

The instructions go on display Thursday in the Bratwurst Museum near the eastern city of Erfurt, Thuringia's capital.