Shinpaku (white core of the rice grain)

Shinpaku (also read kokoro shiro) is the white, opaque area at the center of a rice grain. Its defining feature is that the starch granules inside are coarse and the structure is soft. For this reason, rice with shinpaku is well suited to making high-quality koji. Koji mold penetrates easily into the interior of shinpaku rice, and as a result saccharification progresses more readily during fermentation. The presence of shinpaku also makes it possible to adjust how well the steamed rice dissolves in the moromi (fermentation mash), which contributes to better sake quality. Shinpaku is generally found more often in large-grained sake rice (shuzo kotekimai). It absorbs water readily and is valued as a welcome trait in sake brewing. For this reason, it is regarded as an important factor influencing the quality of sake.