Commonly speaking, Teutonic is a way to ironically refer to German people. Due to the well-known cliché of German efficiency, I think your book uses Teutonic in this sense.

Teutons were an ancient Germanic tribe - you can read a bit about them here. They had been one of the first Germanic tribes to meet the Romans, at the end of the 2nd century BCE.

Though originally limited to this particular Germanic tribe, the term was soon used in a broader sense to indicate any Germanic people (for example, the phrase furor Teutonicus appearing in Lucan's Pharsalia).

In the Middle Ages, however, the name was revived as a Latin equivalent to Deutsch, especialli with reference to the Teutonic Knights: the German military order named Orden der Brüder vom Deutschen Haus St. Mariens in Jerusalem (Order of Brethren of the House of St. Mary of the Germans in Jerusalem) was called in Latin Ordo domus Sanctæ Mariæ Theutonicorum Hierosolymitanorum, whence the common denomination of Teutonic Knights. Their domain centered in the Baltic Lands, ultimately gave birth to Modern Age Prussia, which was famed for its hardness and stern attention to rules and authority. I suppose that the use of Teutonic as a derogatory term for the Germans stems from this Prussia stereotype.