14B-23

A. KANAVOURAS and R. J. HERNANDEZ. School of Packaging, Michigan State University, East Lansing, MI 48824

Volatile non-glyceride compounds of olive oil such as antocyanins, hydrocarbons, tocopherols, flavonoids, sterols, and phenolic constituents are recognized to impart nutritional and flavor characteristics to the oil. The oxidation process of non-glyceride compounds play an important role in determining the quality and shelf life of plastic-packaged olive oil.

Our objective was to compare two techniques for quick and accurate isolation and characterization of volatile compounds in olive oil in order to monitor the quality pameters of packaged oil.

The Dynamic Headspace–Thermal Desorption (DHS-TD) and Solid Phase Micro-extraction (SPME) techniques were chosen for their efficiency in trapping headspace volatile compounds. Tenax-TA and Carbotrap-300 trapping materials were selected. For compound isolation in the DHS-TD, 250 ml and 9 ml vials were used at 30°C, while sampling by SPME was carried out in 12 ml vials at 20-22°C with PDMS (Polydimehtysiloxane) - 1 cm x 100 mm and Polydimehtysiloxane-Divinylbenzene – 1 cm x 65mm fibers. Isolated volatiles were analyzed by GC-Ion Trap MS for DHS-TD and GC-Time of Flight-MS for SPME. The two techniques were applied to virgin and accelerated oxidized olive oil.

The Tenax-TA/DHS-TD is a complex technique, provides a large number of isolated compounds (about one hundred), and requires long operational times (about two hours). By comparison, the Polydimehtysiloxane-Divinylbenzene, SPME, is a simple and quick technique, although provides only few volatiles. Both techniques worked better for the higher ratio of product/headspace.

Selection of proper fiber and conditions could make SPME useful for a quick identification of the major quality-related volatile compounds from olive oil. When more accurate measurements and extended types of compounds are of interest, DHS-TD can be used, after selecting the proper values of product/headspace ratio, amount of sample, purging conditions and trapping material.