Saturated vapour pressure of aroma compounds at various temperatures

The aim of this study was to determine experimentally the vapour pressures of aroma compounds at various temperatures, especially at negative ones. The aroma compounds were: acetone, 2-butanone, 2-hexanone, 2-octanone, ethyl acetate, ethyl butanoate, ethyl hexanoate, n-hexanal, n-hexanol and γ-hexalactone. The technique used was a static device where vapour pressure was measured at equilibrium. The temperatures of analysis varied from −40 to 25 °C. Volatility of a pure compound depends on characteristics such as length of the aliphatic chain, the functional group and temperature. Among an homologous series, volatility increases when the aliphatic chain decreases and when temperature increases. For aroma compounds which have the same number of carbon atoms in their structure, volatility depends not only on either temperature or molecular weight, but also on the functional group of the molecule. At a given temperature volatility of compounds which have the same number of carbon atoms in their structure, decreases as follows: ester> ketone> aldehyde> alcohol> lactone.