Flavour release of aldehydes and diacetyl in oil/water systems

The concentration- and time-dependent release of three C-6-aldehydes, six C -9-aldehydes and diacetyl was studied in model systems. The systems were wa ter, rapeseed oil and oil-in-water emulsions. Dynamic headspace sampling wa s used to collect the volatile compounds. In the concentration-dependent re lease experiment, the C-6-aldehydes were released in equal proportions from the aqueous and the emulsion systems, but in lower amounts from the pure o il. The amounts of C-9-aldehydes released decreased with increasing oil con tent. All aldehydes were released more rapidly from the aqueous system than from the pure oil. The release over time for diacetyl and (E,E)-2,4-hexadi enal showed a linear relationship in all systems. The other compounds follo wed an exponential relationship between the time and the fraction released in the aqueous systems. It was demonstrated that the release of the volatil e compounds was dependent on the chain length, the degree of unsaturation a s well as the characteristics of the model system. (C) 2000 Elsevier Scienc e Ltd. All rights reserved.