Polished barley and polished rice were enriched with the saturated alcoholic solution of riboflavin tetrabutylate and the amount of riboflavin tetrabutylate in them was determined after they were washed with water for various periods of time. After washing for 5,10,15 and 20 minutes, the amount of riboflavin tetrabutylate which remained in the barley was 78.4,73.0,70.3 and 68.9 %, respectively, while, that in the rice was 39.3,30.4,28.6 and 25.0%. The difference of data between barley and rice was clearly remarkable. Accordingly, the enrichment of polished barley by riboflavin tetrabutytate may be performed easily, but that of polished rice must be further investigated.
