Exploring the bioresource potential of beech nuts (Fagus sylvatica L.) from different regions of Spain: geographical origin impact on composition and antioxidant activity

Beech nuts ( Fagus sylvatica L.) are an underutilized resource with promising nutritional and functional potential. This study analysed physicochemical characteristics of nuts collected from three Spanish regions (Burgos, León, and Palencia) and applied chemometric tools to identify geographical biomarkers. All samples displayed antioxidant activity, with the highest levels observed in samples from Palencia. Although volatile compound profiling showed region-specific patterns dominated by aldehydes, the mean sensitivity achieved for repeated K-fold cross-validation (88%) led to several misclassifications, limiting its applicability as a non-invasive approach for geographical origin discrimination. The extracted oils (17–22% dw) were rich in unsaturated fatty acids, mainly oleic acid (35.2–39.3%) and linoleic acid (36.0–38.0%), with significant regional variation. Moisture and specific fatty acids (C 16:1 , C 18:3 , C 20:2 , C 22:0 , C 22:1 ) were identified as reliable markers of geographical origin, allowing a very satisfactory predictive performance (98% for repeated K-fold-CV). Beech nut oils were also rich in tocopherols (441–551 mg/kg), with γ-tocopherol as the predominant form. The identification of region-specific differences in composition and antioxidant capacity offers clear industrial advantages by enabling the targeted selection of raw materials with tailored nutritional, functional, and quality attributes, while also supporting traceability. Overall, the findings highlight beech nuts as a promising bioresource with potential applications as a functional ingredient in different industries. • Beech nuts are rich in unsaturated fatty acids, mainly oleic and linoleic acids • Fatty acids were identified as key biomarkers of geographical origin • Oils contain high tocopherol levels, particularly γ-tocopherol • Strong antioxidant activity supports functional and health-promoting properties • Promising bioresource for food, cosmetic, and pharmaceutical applications