The volatile profiles of a rare apple (Malus domestica Borkh.) honey: shikimic pathway derivatives, terpenes and others

The volatile profiles of rare Malus domestica Borkh. honey were investigated for the first time. Two representative samples from Poland (sample I) and Spain (sample II) were selected by pollen analysis (44 –45% of Malus spp. pollen) and investigated by GC/FID/MS after headspace solid-phase microextraction (HS-SPME) and ultrasonic solvent extraction (USE). The apple honey is characterized by high percentage of shikimic acid-pathway derivatives, as well as terpenes, norisoprenoids, and some other compounds such as coumaran and methyl 1H-indole-3-acetate. The main compounds of the honey headspace were (sample I; sample II): benzaldehyde (9.4%; 32.1%), benzyl alcohol (0.3%; 14.4%), hotrienol (26.0%, 6.2%), and lilac aldehyde isomers (26.3%; 1.7%), but only Spanish sample contained car-2-en-4-one (10.2%). CH2Cl2 and pentane/Et2O 1:2 (v/v) were used for USE. The most relevant compounds identified in the extracts were: benzaldehyde (0.9–3.9%), benzoic acid (2.0–11.2%), terpendiol I (0.3–7.4%), coumaran (0.0–2.8%), 2-phenylacetic acid (2.0–26.4%), methyl syringate (3.9–13.1%), vomifoliol (5.0 –31.8%), and methyl 1H-indole-3-acetate (1.9–10.2%). Apple honey contained also benzyl alcohol, 2-phenylethanol, (E)-cinnamaldehyde, (E)-cinnamyl alcohol, eugenol, vanillin, and linalool that have been found previously in apple flowers, thus disclosing similarity of both volatile profiles.