Metabolomic profiling olive stone (Olea europaea L.): influence of tree age, cultivar, and geographic origin on phytochemistry composition

Olive stones (Olea europaea L.) represent a valuable by-product of the olive oil industry with considerable untapped economic potential. In the present study, olive stones from seven Egyptian cultivars were analyzed using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC–MS), followed by visualization through chemometric tools. For the first time, the influence of tree age (4, 5, 7, 9, 10, 12, 15, 20, and 25 years), cultivar type (Akasy, Coratina, Eggizi, Manzanillo, Picual, Shemlali, and Tufahi), and geographical origin (Fayoum, Ismailia, Arish, North Sinai—Bi’r ar-Rummanah, and Zuweid) on the olive stone metabolome was comprehensively evaluated. The effects of these factors were evaluated through stratified supervised models in which each factor was examined while the others were held constant. In total, 81 samples were subjected to untargeted metabolomics analysis, with 24 markers, including 7 phytochemicals reported for the first time in olive stones, broadening the known chemical inventory of this by-product and indicating potential nutraceutical and industrial relevance that remains to be functionally validated. Multivariate data analysis revealed distinct metabolite markers associated with tree age, cultivar type, and geographical origin. Fatty acids were consistently detected across all seven cultivars, irrespective of age or location. Notably, certain cvs. exhibited characteristic metabolic signatures: Picual stones were enriched in acylphloroglucinols and triterpenoid saponins; Akasy stones showed higher levels of triterpenoid saponins; whereas Tufahi stones were particularly abundant in secoiridoids and flavonoids.