Characterization of volatiles and identification of odor-active compounds of rocket leaves

Abstract

The volatile profile of crushed rocket leaves (Eruca sativa and Diplotaxis tenuifolia) was investigated by applying Headspace Solid-Phase MicroExtraction (HS-SPME), combined with GC-MS, to an aqueous extract obtained by homogenization of rocket leaves, and stabilized by addition of CaCl₂. A detailed picture of volatile products of the lipoxygenase pathway (mainly C6-aldehydes) and of glucosinolate hydrolysis (mainly isothiocyanates), and their dynamics of formation after tissue disruption was given. Odor-active compounds of leaves were characterized by GC-Olfactometry (GC-O) and Aroma Extract Dilution Analysis (AEDA): volatile isolates obtained by HS-SPME from an aqueous extract and by Stir-Bar Sorptive Extraction (SBSE) from an ethanolic extract were analyzed. The most potent odor-active compounds fully or tentatively identified were (Z)- and (E)-3-hexenal, (Z)-1,5-octadien-3-one, responsible for green olfactory notes, along with 4-mercaptobutyl and 4-(methylthio)butyl isothiocyanate, associated with typical rocket and radish aroma. Relatively high odor potency was observed for 1-octen-3-one, (E)-2-octenal and 1-penten-3-one.

Keywords: (E)-2-octenal (PubChem CID: 5283324); (E)-3-hexenal (PubChem CID: 643139); (Z)-1,5-octadien-3-one (PubChem CID: 6429343); (Z)-3-hexenal (PubChem CID: 643941); 1-octen-3-one (PubChem CID: 61346); 1-penten-3-one (PubChem CID: 15394); 4-(methylsulfinyl)butyl isothiocyanate (PubChem CID: 5350); 4-(methylthio)butyl isothiocyanate (PubChem CID: 78160); 4-mercaptobutyl isothiocyanate (PubChem CID: 85704368); Aroma extract dilution analysis; Diplotaxis tenuifolia; Eruca sativa; GC-olfactometry; Isothiocyanates; Key odorants; Lipoxygenase pathway; Myrosinase; tetrahydrothiophene (PubChem CID: 1127).