Determination of the degree of polishing in rice. I. Some methods for comparison of the degree of milling.

In three varieties of rice, the proportion of grains with lost germs steadily
increased with progressive increase in the degree of polishing. Staining
of the rice grains with methylene blue followed by congo red could be
used for qualitative inspection of the degree of polishing. The absorbed
congo red could be eluted with pyridine.
The pigments of rice bran gave color reactions with alkaline methanol
and with sodium nitrite. The intensity of color in these reactions decreased
progressively on milling. Phytin values determined by a colorimetric
method and an indirect estimation of fat by measuring its iodine absorption
capacity showed that milling progressively reduced the phytin and fat
contents in rice.
Simple and rapid procedures for measuring variations in the different
characteristics of the rice grain as a result of subjection to progressive polishing
have been described. Some of these procedures have been found suitable
for a semiquantitative comparison of the degree of milling in rice.