Enzyme activity / Enzyme titer
Enzyme activity / titer
Japanese: 酵素力価（こうそりきか）
A numerical indicator of how fast an enzyme can break down its substrate. An essential measurement for evaluating koji quality.
Enzyme titer is a numerical measure of how much substrate an enzyme can break down per unit time. It is measured individually as protease activity, amylase activity, and so on.
Koji quality is objectively evaluated by enzyme titer. Even with the same koji mold strain, enzyme titer varies greatly with cultivation conditions (temperature, humidity, time), affecting the final miso. The art of koji-making is essentially the art of consistently achieving high enzyme titers.
Industrial standardized methods (Folin method, Somogyi-Nelson method) are used, and koji producers trade with guaranteed enzyme titers. Even for homemade miso, higher koji enzyme titer means greater potential for umami-rich miso—measuring an invisible force.