Site of Origin of Volatile Compounds in Cooked Rice

• Published in: Cereal chemistry 2008-09, Vol.85 (5), p.591-598
• Main Authors: Yang, Dong Sik, Lee, Kyu-Seong, Kim, Kee-Jong, Kays, Stanley J
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Cereal and baking product industries; cooked foods; cooked rice; cultivars; food analysis; food composition; Food industries; Fundamental and applied biological sciences. Psychology; milling; Oryza sativa; rice; volatile compounds
• ISSN: 0009-0352; 1943-3638
• DOI: 10.1094/cchem-85-5-0591

Volatile compounds emanating from three cultivars of cooked rice milled to different degrees (0, 8, and 30% by weight) were compared to ascertain their site of origin and the effect of pigmentation on synthesis. The cultivars tested were Ilpumbyeo (traditional white rice), Heugjinjubyeo (black pigmented), and Jeogjinjubyeo (red pigmented). In total, 29, 38, and 27 volatile compounds were identified in dehulled, unmilled Ilpumbyeo, Heugjinjubyeo, and Jeogjinjubyeo, respectively. Significant quantitative and qualitative differences were found among the cultivars in their volatile profiles. 2-Acetyl-1-pyrroline, guaiacol, 1-nonanol, 3-octen-2-one, 1,2-dimethoxybenzene, pyridine, and pyrrole were found only in Heugjinjubyeo and phenylacetaldehyde only in Jeogjinjubyeo. Removal of the bran, partial endosperm, and pigment qualitatively and quantitatively affected the volatile compounds formed, with certain volatiles higher in unmilled rice (0% milling), indicating the pericarp and aleurone layer (bran) as their primary site of origin. Volatiles emanating from the 8 and 30% milled samples indicated the outer and middle endosperm (8%) and core endosperm (30%) as the primary sites of origin. Therefore, differences in chemical composition with location within the grain appear to account for the quantitative and qualitative variation in volatile synthesis.