Volatile Compounds and Sensory Profiles of Monovarietal Virgin Olive Oil from Bu?a, ?rna and Rosinjola Cultivars in Istria (Croatia)

摘要

The volatile compounds found in virgin olive oil, mainly C6 and C5 volatile compounds biogenerated from polyunsaturated fatty acids through the lipoxygenase pathway, are responsible for their particular aroma. The composition of volatile compounds in olive oil depends on the cultivar, the ripening degree of the fruits and processing conditions. Among many different autochthonous cultivars in Istria (Croatia), some of the most prevalent are Bu?a, ?rna and Rosinjola. The volatiles and sensory characteristics of their monovarietal virgin olive oil are little known. Therefore, fruits from these three cultivars were handpicked at the same ripening degree and processed under the same conditions. Quantitative descriptive sensory analysis of monovarietal virgin olive oil was carried out by the panel. Volatile composition was evaluated by headspace solid phase microextraction-gas chromatography, previously optimized and validated. The main parameters affecting effectiveness, time and temperature of extraction were optimized. The extraction procedure showed detection and quantification limits, as well as linear ranges adequate for the analysis of selected volatile compounds. Good precision was obtained both in terms of intra-day repeatability (relative standard deviations generally lower than 7 %) and inter-day precision. The tested types of monovarietal olive oil showed different volatile profiles, although E-2-hexenal was the main compound in all samples. Bu?a oil was the richest in total C6 and C5 volatile compounds. The results show that the most important contributors to the olive oil aroma (odour activity value >1.0) were 1-penten-3-one, E-2-hexenal, hexanal, hexanol, Z-3-hexen-1-ol and Z-2-penten-1-ol. These chemical findings were compared with those provided by the panel test. Bu?a had the highest intensity of sensory characteristic 'other ripe fruits' and Rosinjola had the highest intensity of sensory characteristic 'bitter'. All results show that olive oil aroma compounds accumulate differently depending on the cultivar, indicating a close dependence on the enzymatic pool, which is genetically dependent.