Location: Warmwater Aquaculture Research UnitTitle: Characterization of Fish Sauce Aroma Impact Compounds Using GC-MS, SPME-Osme-GCO, and Stevens' Power Law Exponents Author
Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/23/2008
Publication Date: 2/5/2008
Citation: Pham, A.J., Schilling, M.W., Yoon, Y., Kamadia, V.V., Marshall, D.L. 2008. Characterization of Fish Sauce Aroma Impact Compounds Using GC-MS, SPME-Osme-GCO, and Stevens' Power Law Exponents. Journal of Food Science. 73(4):C268-C274. Interpretive Summary: It is apparent from this research that SPME-Osme-GCO can be utilized to differentiate between aroma intensities and odor impact compounds in foods that contain both a high concentration of water and aroma compounds. In this study, Stevens' Power Law exponents were moderately effective at explaining the relationship between sample concentration and odorant intensity, but the exponents were not consistent among fish sauce samples for identical odors. This demonstrates that there is variability in Stevens' Power Law exponents for odors within fish sauce samples. It appears that combining Osme-GCO with compound threshold information may be useful in food products since the determination of threshold, flavor unit, and the n value would theoretically allow for an enhanced explanation of the contribution of an odor to the overall flavor of a food product at different concentrations. This may be helpful in model systems when attempting to reproduce an odor such as fish sauce, soy sauce, or any other food flavor that is desired since n values could help explain how changes in compound concentration in a model system would affect the overall flavor of that system.
Technical Abstract: The objectives of this study were to characterize volatile compounds and to determine the characteristic aromas associated with impact compounds in 4 fish sauces using solid-phase micro-extraction, gas chromatography-mass spectrometry, Osme, and gas chromatography olfactometry (SPME-Osme-GCO) coupled with Stevens' Power Law. Compounds were separated using GCMS and GCO and were identified with the mass spectral database, aroma perceived at the sniffing port, retention indices, and verification of compounds by authentic standards in the GCMS and GCO. Aromas that were isolated and present in all 4 fish sauce samples at all concentrations included fishy (trimethylamine), pungent and dirty socks (combination of butanoic, pentanoic, hexanoic, and heptanoic acids), cooked rice and buttery popcorn (2,6-dimethyl pyrazine), and sweet and cotton candy (benzaldehyde). All fish sauces contained the same aromas as determined by GCO and GCMS (verified using authentic standard compounds), but the odor intensity associated with each compound or group of compounds was variable for different fish sauce samples. Stevens' Power Law exponents were also determined using this analytical technique, but exponents were not consistent for the same compounds that were found in all fish sauces. Stevens' Power Law exponents ranged from 0.14 to 0.37, 0.24 to 0.34, 0.09 to 0.21, and 0.10 to 0.35 for dirty socks, fishy, buttery popcorn, and sweet aromas, respectively. This demonstrates that there is variability in Stevens' Power Law exponents for odorants within fish sauce samples.