Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2010
Publication Date: 1/1/2011
Citation: Johanningsmeier, S.D., Mcfeeters, R.F. 2011. Detection of volatile spoilage metabolites in fermented cucumbers using nontargeted, comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGC-TOFMS). Journal of Food Science. 76(1):C168-C177.
Interpretive Summary: The chemistry of food fermentations is very complex because the interactions between the starting food material and the huge numbers of microorganisms that grow and chemically change many of the original food components. Among the components present in fermented food products are many volatile compounds, some of which are responsible for characteristic odor of the food. This project has developed a very sensitive, high resolution technique to identify and measure the changes in volatile components in fermented cucumbers before and after they spoil. With this new method it was possible to show that there are over 300 different volatile components in fermented cucumbers. Thirty five of these volatile compounds changed significantly when the fermented cucumbers spoiled. Over 200 of these compounds were either positively or tentatively identified. This approach to analysis of volatile food components can be applied to help us analyze and better understand other complex food systems.
Technical Abstract: A nontargeted, comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGC-TOFMS) method was developed for the analysis of fermented cucumber volatiles before and after anaerobic spoilage. Volatiles extracted by solid-phase microextraction were separated on a polyethylene glycol first-dimension column and 14% cyanopropylphenyl second-dimension column. Among 314 components detected in fermented cucumber brine, 199 had peak areas with coefficients of variation below 30%. Peak identifications established by mass spectral library matching were 92% accurate based on 63 authentic standards. Analysis of variance of analytes’ log peak areas revealed 33 metabolites changed in concentration after spoilage (P < 0.05), including increases in acetic, propanoic, and butyric acids, n-propyl acetate, several alcohols, and a decrease in furfural. GCxGC-TOFMS with a nontargeted, semi-automated approach to data analysis made possible the separation, identification, and determination of differences in polar volatile components, facilitating the discovery of several metabolites related to fermented cucumber spoilage.