Effect of microwaves on volatile compounds in origanum

A headspace-solid-phase microextraction-capillary gas-chromatography method was used to evaluate the effect of microwave treatment on volatile compounds of origanum (Origanum vulgare L.). The extraction of volatile compounds was performed using a 50/30 divinylbenzene/carboxen on polydimethylsiloxane on a 2 cm StableFlex fiber (Supelco). The most significant chromatographic peaks were identified using standard materials and GC-MS analysis. The analyses were conducted on samples, treated and non-treated with microwaves, coming from two different types of origanum. The results obtained were submitted to univariate and multivariate statistical analysis. Data obtained allowed to identify the principal differences between the two types of origanum and showed that type 1 (thymol/carvacrol chemotype) is less influenced by microwave treatment than type 2 (carvacrol chemotype). Considering the most important components for origanum aroma, thymol and carvacrol, the differences found are only marginally significant between treated and non-treated samples of all types of origanum considered. (C) 2003 Swiss Society of Food Science and Technology. Published by Elsevier Science Ltd. All rights reserved.