The aroma compounds of an emulsion of citral (a mixture of geranial and neral) stored for 4 days at 40 °C in an aqueous 5% citric acid solution (pH 1.8), were analysed by high resolution gas chromatography and eluate sniffing. The aroma compounds resulting from the breakdown of citral were identified as α,p-dimethylstyrene, p-cymen-8-ol, pmethylacetophenone, o- and p-cresol. In addition pcymene was present in the gas chromatogram but it was not detected during eluate sniffing. p-Methylacetophenone, o- and p-cresol showed significantly lower odour thresholds (2.7-10.8; 0.7-2.7; 0.3-1.0 ng/l air, respectively) than a,p-dimethylstyrene (665-2660 ng/1 air). The reactions leading to the production of pmethylacetophenone are discusse