Metabolite profiling and antioxidant activity of the polar fraction of Italian almonds (Toritto and Avola): Analysis of seeds, skins, and blanching water

The health benefits of almonds along with their ability to prevent atheroschlerosis as well as cardiovascular and diabetes risks are well known. Previous works were focused mainly on the lipid fraction, thus a lack of information about the polar constituents still persists. In order to provide deeper insight into the chemical composition of almond, the polar fraction of Italian almond cultivars (Toritto and Avola) was investigated. The MeOH extract of the Toritto cultivar was submitted to LC-ESI-(HR)MS/MS experiments, highlighting the occurrence of several compounds, mainly cyanogenic glycosides, glycosylated flavonoids, proanthocyanidins, and a diterpene glycoside. EtOH and EtOH:H2O solution were also employed for extractions, resulting selective for flavonoids and proanthocyanidins, while cyanogenic glycosides were mainly detected in EtOH:H2O extract. Almonds were also blanched to afford skins and blanching water which were analyzed by LC-ESI-(HR)MS/MS experiments in order to establish the source of the identified compounds. Cyanogenic glycosides were detected in the peeled almonds, while flavonoids and proanthocyanidins were detected in almond skins and blanching water. The LC-ESI-(HR)MS/MS analyses of the almonds of the Avola cvs (Fascionello, Pizzuta and Romana) were compared with those of the Toritto cv., showing clear differences in their metabolome, probably due to the different growing conditions. Finally, total phenolic content and radical scavenging activity of the extracts and blanching waters were evaluated by Folin-Ciocalteu assay and by DPPH[rad] and ABTS[rad]+ assays, highlighting interesting antioxidant properties possessed by almond skins and blanching water, suggesting their potential employment in pharmaceutical, cosmetic and nutraceutical formulations