Soybean (Glycine max)
Soybean
Japanese: 大豆（だいず）
The primary ingredient of miso. Rich in protein, broken down into amino acids through fermentation.
Soybeans are so protein-rich they are called 'meat of the field.' In miso making, protein is broken down into amino acids by koji enzymes, creating the foundation of umami.
Size and sweetness vary by cultivar and origin, affecting the final product. Careful soaking, steaming, and mashing ensure even fermentation when mixed with koji. Soybeans may seem unassuming, but they are the true protagonist of miso flavor. Large domestic cultivars have pronounced sweetness, adding depth to finished miso. Trying different varieties is also a delightful discovery.