Quality of production became the central concern of German vine-growers and administrators after 1800. The beginnings of quality delimitation can be traced to the 1830s. Wine ordinances in the German states began to prescribe that grapes of different levels of ripeness should be harvested separately. Their measurement was greatly facilitated by systems for weighing the must to achieve a specific must weight, refined in the 1830s by the Pforzheim physicist Ferdinand oechsle, whose system is still in use today.