noun
high-quality buckwheat flour; first-grade soba flour
Made only from the white center of the buckwheat grain, yielding a pale, fine flour prized for delicate soba noodles.
更科粉で打ったそばは色が白く、のどごしが良い。
Soba made with sarashina flour is pale in color and has a smooth texture.
First-milled buckwheat flour, which is also pale and fine, but 更科粉 specifically refers to flour from the center of the grain.
更科 (Sarashina) is a place name in Nagano Prefecture historically associated with high-quality soba; 粉 means 'flour'. The term refers to flour made in the Sarashina style, using only the endosperm.