Antioxidant Capacity and Polyphenolic Profile of Extractable and Non-Extractable Fractions of Traditional Mediterranean Diet Recipes from Different Regions

Abstract

The Mediterranean Diet (MD) is recognized for its nutritional quality, health-promoting properties, and richness in bioactive compounds, yet studies analyzing complete traditional recipes considering both extractable and non-extractable fractions are limited. This study characterized the total antioxidant capacity (TAC) and phenolic profile of 56 traditional MD recipes from eight countries, grouped into European Mediterranean (France, Italy, and Spain), African Mediterranean (Tunisia, Algeria, and Morocco), and non-Mediterranean European (Luxembourg and Germany) regions. Samples were freeze-dried and subjected to aqueous-organic extraction followed by acid hydrolysis. TAC was measured using TEAC, ORAC, and total phenolics (Folin-Ciocalteu, reflecting reducing capacity), while phenolic profiles were analyzed by HPLC-DAD. Relationships between phenolics and TAC were evaluated using linear and mixed-effects models, accounting for country-level heterogeneity. Mediterranean recipes showed higher TAC and greater phenolic diversity than non-Mediterranean recipes, with a predominance of phenolic acids, secoiridoids, and flavonoids, reflecting characteristic olive oil use. In all regions, the non-extractable fraction contributed >80% to TAC, highlighting underestimation by conventional methods and its dominant contribution to dietary antioxidant intake. TEAC was positively associated with extractable phenolics, whereas ORAC reflected country-specific culinary features independently of total phenolic content. These findings underscore the significant bioactive potential of traditional MD recipes, which can be considered functional foods, and the importance of comprehensive evaluations of both extractable and non-extractable fractions for nutritional research and dietary interventions.