SPME analysis of volatile compounds from unfermented olives subjected to thermal treatment

The effect of different types of thermal treatment, designed to increase the product's shelf-life, on the volatile composition of "Campo Real" unfermented table olives, has been studied by headspace solid-phase microextraction (HS-SPME) and GC-MS analysis. Different SPME fibres were evaluated to determine their selectivity for a mixture of the main components of the different spices used in "Campo Real" olive dressing. Of the different fibres investigated, the polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre was selected for analysis of the olive brines, which contained nine main aroma components. The types of thermal treatment were sterilisation (121 degrees C, 15 min) and four pasteurisation conditions (60 degrees C or 80 degrees C each for 5 or 9 min). Pasteurisation did not lead to significant changes in the amounts of these nine volatile compounds; the 2-butanol signal was reduced by treatment at 80 degrees C. On the other hand, sterilisation of the brine resulted in an decrease in the signals from these compounds and the appearance of a new, high signal for benzaldehyde; the origin of this has not yet been determined. Results suggest that the selected pasteurisation conditions do not significantly modify the typical, and valued, aroma characteristics of "Campo Real".