Gaiko nainan (ideal steamed rice: firm outside, soft inside)

Gaiko nainan (外硬内軟) refers to steamed rice that has been steamed to an ideal condition during the sake brewing process. In this state, the outside of each grain is firm, while the inside is soft and springy. Specifically, the surface is not sticky, and when the rice is squeezed in the hand it has a firm springiness, yet no hard core can be felt in the center. Steamed rice of this kind is considered essential for making high-quality koji and for brewing moromi (fermentation mash). Gaiko nainan rice is the result of the rice being steamed evenly, which produces this ideal texture, and it plays an important role in sake brewing.