Evaluation of the Quality and Composition of the Lipid Fraction Obtained from Acorns

Acorns represent an underutilized source of forest biomass with potential for producing edible oils and bioactive compounds. This research compared lipid fractions from pedunculate oak (Quercus robur L.) and northern red oak (Quercus rubra L.) collected in Poland, examining how different extraction methods influence oil yield and quality. Oils were extracted using Soxhlet with hexane, cold hexane extraction for both species, and mechanical pressing for Q. rubra. Fatty acid profiles analyzed by GC-FID facilitated calculation of lipid quality indices. Oxidative stability was assessed through isothermal PDSC, and total phenolics, flavonoids, and antioxidant activity (DPPH, ABTS) were measured in acorn extracts. Q. rubra produced more oil than Q. robur regardless of extraction method, but Q. robur oils exhibited significantly higher PDSC oxidation times (τon, τmax). Pressed Q. rubra oil showed higher acid and peroxide values compared to solvent-extracted oils. Fatty acid composition was predominantly influenced by species rather than by extraction method, as confirmed by multivariate analysis, which indicated species as the main driver of variability. Overall, these results highlight a trade-off between oil yield and oxidative stability, suggesting acorns as a promising, species-dependent oil resource.