New Delhi, June 20 -- What happens when steamed grains are laid out under muslin, left to rest in warm, humid air? Within days, a delicate white bloom spreads across the surface, releasing a nutty, almost chestnut-like aroma. It might appear to be a science experiment, but, in fact, is a culinary revolution in slow motion-koji, or Japanese fermented rice (or barley) mould that is quietly building flavour blocks in Indian gastronomy.

Koji has long been revered in Japan for its ability to break down starches and proteins into sugars and amino acids, unlocking deep savoury flavour, what chefs and scientists alike call umami. Once confined to Japanese kitchens, the fungi Aspergillus oryzae is now being harnessed by a growing tribe of Indian ...