Determination of flavour profile in Iranian fragrant rice samples using cold-fibre SPME-GC-TOF-MS

A newly developed cold-fibre solid-phase microextraction (CF-SPME) device, as a powerful system for collection and concentration of volatile compounds, coupled to a gas chromatography time-of-flight mass spectrometer (GC-TOF-MS) system, equipped with a multi-channel ion detector and a deconvolution software, was investigated for the analysis of volatile flavour compounds in the headspace of rice samples. The proposed combination provided a powerful system for easy and rapid screening of a wide range of flavours in fragrant rice samples. Based on four target analytes, including 2-acetyl-1-pyrroline as a key odorant compound, different experimental parameters were optimized. The effect of the fibre composition, moisture present in the matrix, extraction temperature and time and desorption time were investigated. Nine Iranian and two Indian fragrant rice varieties were analysed using CF-SPME and the results were compared with commercial SPME fibres. The results revealed that uncooked rice samples can be successfully analysed even as dry kernels, without adding water, utilizing the fully automated CF-SPME-GC-TOF-MS. When using PDMS fibre, a clearly distinguishable peak was seen for 2-acetyl-1-pyrroline by simultaneous cooling of the fibre and heating of rice matrices as dry whole grains. Copyright (c) 2007 John Wiley & Sons, Ltd.