Gc-olfactometry with solid phase microextraction of aroma volatiles from heated and unheated orange juice

Solid phase micro extraction, SPME, the solventless headspace volatile extraction technique, was combined with GC-olfactometry (GCO) to examine changes in aroma active volatiles when orange juice was heated. Juice volatiles extracted from the static headspace using SPME (carboxen-polydimethylsiloxane fiber) were compared to liquid-liquid extracts. The SPME extract contained a greater proportion of terpenes. Limonene, myrcene and alpha-pinene comprised 86% of total FID peak area whereas they only comprised 24% in the pentane:ether extract. Aroma active volatiles were evaluated by three trained panelists using Osme, a GCO time-intensity procedure. Eighteen aroma active peaks were common to both heat treated and untreated juice headspace extracts. Six peaks were observed only in unheated extracts and five were found only in extracts from heated juices. Relative amounts of acetaldehyde decreased with increasing headspace exposure time and elevated desorption temperatures.