Analysis of volatile components in Khao Dawk Mali 105 (KDML 105) grains by GC x GC-TOFMS

Khao Dawk Mali 105 (KDML 105) (Oryza sativa L) is well known as Thai jasmine rice. The major aroma component of KDML 105 is 2-Acetyl-1-pyrroline (2AP). Besides the 2AP, KDML 105 contains various volatile components which contribute aroma and flavor to the rice. Moreover, hydrocarbons, aldehydes, ketones, and alcohols are also found in the rice sample. Due to the complex nature of the sample, some volatile components which co-elute with rice matrix components are not easily identified using traditional GC-MS. GCxGC-TOFMS is a new technique that increases peak capacity and enhances peak sensitivity. The research described here used GCxGC-TOFMS to identify components in the complex mixture of KDML 105 grain sample extracts. Two columns with different stationary phases were employed. The columns were connected using a press tight connector, located just before a dual stage thermal modulator, coupled to a Time of Flight Mass Spectrometer (TOFMS). In this study 390 components were found in the extracts of KDML 105 grain samples using GCxGCTOFMS (at S/N  50) which were found more than traditional GC-MS about 3 – 8 times. 2-AP was found as a main aroma flavourant and other groups of components such as 170 hydrocarbons, 58 alcohols, 39 aldehydes, 49 ketones and so on were also found in the samples. In addition, some components which overlapped in the first dimension separation could be separated in the second dimension resulting in higher mass spectral quality for confident identification