Identification of potent flavor compounds formed in an aqueous lemon oil/citric acid emulsion

The flavor compounds of a fresh and a stored (30 days at 37 ^°C) emulsion of lemon oil in an aqueous citric acid solution were analyzed by high-resolution gas chromatography and eluate sniffing. Application of this technique on stepwise-diluted extracts of the volatile compounds allowed the determination of a new parameter, the FD factor, which reveals the most intense flavor compounds of the extract. On the basis of their high FD factors, geranial, neral, and linalool were identified as the most intense volatile flavor compounds of the fresh lemon oil. Lower FD factors were found for myreene, limonene, γ-terpinene, octanal, nonanal, citronellal, 2(E)-nonenal, and decanal. After storage, neral, geranial, and citronellal were no longer sensorially detectable. On the other hand, p-methylacetophenone, p-cresol, fenchyl alcohol, p-cymene, and 1-terpinen-4-ol were formed during storage and showed high FD factors.