Studies on the volatile components of rice and rice bran. I. Fractionation and identification of volatile acids and phenols in the steam distillate of rice bran.

Fractionationof the volatile concentrate obtained from steam-distillate of rice bran and organoleptic tests of each fraction were carried out.The neutral fraction gave a much higher yield than others and was assumed to be indispensable for the reproduction of rice bran odor.The acidic fraction methylated with diazomethane and the phenolic fraction were analyzed by glass capillary gas chromatography to identify 17 carboxylic acids and 7 phenols.4-Vinylguaiacol and 4-vinylphenol identified in the steam volatile concentrate were considered to be produced from ferulic and p-coumaric acids during steam-distillation.4-Vinylphenol was the main component in the steam volatile concentrate of rice bran, having a characteristic un pleasant odor.Rice is one of important cereal foods in the world, especially in Asia.Cooked rice has a characteristic odor which is widely accepted as