Rapid analysis of volatiles in fat-containing matrices for monitoring bioprocesses

A rapid, single-step method for the analysis of volatile flavours based on the extraction using the medium-chain triglyceride (MCT) Tegosoft CT and subsequent thermal desorption gas chromatography was developed. The MCT was spiked with a mixture of volatile compounds to validate the protocol. Thermal desorption was complete over a dynamic range of more than three orders of magnitude (except γ-dodecalactone) and linear for all constituents of the volatile mixture. The respective limits of detection and quantification were in the range between 12 and 28 mg L^-1 MCT for γ-dodecalactone and 39 and 95 mg L^-1 for isoamyl acetate. The applicability of the method was evaluated with aqueous and lipid-containing matrices which were spiked with a known amount of the volatile mixture and extracted subsequently using MCT. A complete recovery of non-polar, medium recovery of semi-polar and zero recovery of the most polar compound (maltol) showed the potential and limits of the protocol. The kinetics of volatile formation during the cultivation of the basidiomycete Fomitopsis rosea grown in a lipid-enriched medium were monitored.