S. P. L. Sørensen Introduces the pH Scale at the Carlsberg Laboratory

In 1909, Danish chemist Søren Peter Lauritz Sørensen introduced the pH concept while directing the Department of Chemistry at the Carlsberg Laboratory in Copenhagen. Sørensen developed a concise logarithmic method for expressing hydrogen-ion concentration, making acidity easier to measure, compare, and reproduce in biochemical experiments. Sørensen’s work was initially connected with research on proteins and enzymes rather than with a single brewing-water experiment. Nevertheless, the pH scale became fundamental to brewing science because acidity influences mash enzyme activity, fermentation, flavor, microbial stability, and the effect of brewing water on malt. It gave brewers and brewing laboratories a standardized way to evaluate and control chemical conditions that had previously been understood mainly through practical experience.