Analysis of the Volatile Compounds of Aerial Parts and Essential Oil from Thymus serpyllum L. Cultivated in North East Italy by HS-SPME/GC-MS and Evaluation of its Flavouring Effect on Ricotta Cheese

Headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography and mass-spectrometry using the divinylbenzene/carboxen/polydimethylsiloxane fiber was applied for the analysis of flavor profiles of Thymus serpyllum L. aerial parts and the corresponding essential oil. At 30°C, the optimal sampling time determined by the equilibrium time of the major volatile compounds both for the thyme aerial parts and the essential oil was 30 min. Twenty-six volatile compounds were identified. Carvacrol and carvacrol methyl ether were the main compounds (44.9 %). The flavoring effect of different amounts (0.26, 0.33 and 0.40 g ) of essential oil for 100 g of ricotta cheese was studied by HS-SPME/GC-MS. Significant differences (p<0.05) were found for monoterpene hydrocarbons and oxygenated monoterpenes for 0.40 g essential oil/ 100 g ricotta cheese. Interactions between thyme essential oil and ricotta cheese highlighted that hydrocarbons monoterpene and sesquiterpene were retained by ricotta, whilst oxygenated monoterpenes were released