A simple technique for measurement of olfactory thresholds of odorous materials is described. Sensitivity and reproducibility of the method was good, but many precautions must be taken to insure reliability of results. Olfactory thresholds for a number of pure compounds, several of which were identified in potatoes, are presented. In general, sulphur compounds and short-chain unsaturated aldehydes gave the lowest and highest thresholds, respectively. The thresholds of a homologous series of saturated aliphatic aldehydes decreased progressively with increase in chain length from C , to Clo. Similar results were obtained with a series of unsaturated aldehydes. Thresholds of some of the more potent compounds were less than 0.1 of a part per 109 parts of water.

No abstract

The air-water partition coefficients of a series of aldehydes from propanal to decanal in dilute aqueous solution have been measured by gas chromatography. The coefficients did not vary appreciably over the whole series, in contrast to the decreasing vapour pressures of the pure solutes. IntroductionThe aroma of a food is due to the small concentration of volatile compounds in the atmosphere above the food. The concentration of a compound in the atmosphere is controlled by a partition of the volatile compound between the food itself and the air above the food. Since most foods contain 50-go7~ of water it might be expected that this would largely be an air-water partition. A study has therefore been made of the air-water partition coefficients of some normal homologues from C, to C,, at 25" and atmospheric pressure.The concentrations of the aldehydes in the air-and the water-phase were determined with a gas-liquid chromatography (GLC) apparatus equipped with dual flame ionisation detectors.