Koji for barley fermentation

When Russell Jackson described his black barley mole as "done with Japanese koji," he meant koji itself - Aspergillus oryzae, a beneficial mould cultivated on grains - not shio koji, the salted paste many home cooks know. Fermenting barley with koji breaks down starches and proteins into deep, umami-rich compounds: the same transformation behind miso and soy sauce. Applied to a mole base, koji-treated barley pushes flavour firmly into Japanese territory — likely why the judges couldn't identify it as a mole at all. The distinction matters: koji is the mould; shio koji is koji fermented with salt and water into a paste. One cannot reliably substitute for the other.