Aquaculture the rearing of fish and other aquatic animals is the best approach for meeting the increasing demand for aquaculture products worldwide. However, the problem of off-flavor has been documented as a serious setback to aquaculture. Though there are many off-flavors can result in a fish being objectionable, approximately 80% of the rejected fish have the earthy-musty odor, which is primary caused by the presence of either 2-methylisoborneol (2-MIB) or geosmin. Based on the fact that the detection of earthy-musty odorous compounds in fish mainly relied on the sensory method in China, the present study established the instrumental method to detect 2-MIB and geosmin by microwave mediated distillation with headspace solid-phase microextraction and gas chromatography-mass spectrum (MWDE-SPME-GC-MS). Through investigating the effects of the key parameters, microwave processing time and carrier gas flow rate, in microwave mediated distillation on extracts, it is concluded that 6 ruin of microwave time and 70 mL/min nitrogen flow were the optimized condition on which earthy-musty odorous compounds could be completely distilled from fish flesh. Then the earthy-musty odorous compounds were absorbed in the fiber under HS-SPME, and were finally desorbed at 250 degrees C and determined by GC-MS. The limits of detection for 2-MIB and geosmin in fish were both 0.1 mu g/kg. There were significant linear correlation in the range of 1-20 mu g/kg for the two earthy-musty odorous compounds, with calibration coefficients at 0.987 and 0.995, respectively. Therefore, trace levels of earthy-musty odorous compounds at ppb in fish could be quantified by this method with credible results.
Zhang Ting (email@example.com) ; Li Lin; Chen Wei; Song Li-Rong (firstname.lastname@example.org).ANALYSIS OF OFF-FLAVORS IN FISH BY MICROWAVE MEDIATED DISTILLATION WITH HEADSPACE SOLID-PHASE MICROEXTRACTION AND GAS CHROMATOGRAPHY-MASS SPECTRUM,Acta Hydrobiologica Sinica,2009,33(3):449-454