Inter- and Intraspecific Variability in Non-Starch Polysaccharide Composition of Satureja Species from Tunisia:...

Non-starch polysaccharides, the primary structural component of dietary fiber, play critical roles in metabolic and digestive health through multiple physiological mechanisms, yet their composition in Mediterranean aromatic plants remains poorly characterized, limiting the development of novel functional food ingredients. This study provides the first comprehensive NSP profiling of 22 populations across three Tunisian Satureja species (S. nervosa, S. graeca, and endemic S. barceloi), using enzymatic analysis, gas chromatography, and multivariate statistics. Total non-starch polysaccharides reached exceptional levels (21.5 ± 3.0 g/100 g dry weight (DW)), with several populations exhibiting unprecedented soluble fiber proportions exceeding 50%, including population SG4 achieving 79.7%. Monosaccharide analysis revealed uronic acid dominance (42.9-52.5% of total NSP), indicating pectin-rich cell walls with distinct functional properties. Principal component analysis (explaining 61.5-84.9% of variance) demonstrated that populations cluster by fiber chemotype rather than taxonomic classification. Hierarchical and K-means clustering identified three distinct clusters in the soluble and total fiber fractions, with uronic acid-dominated populations (SG4, SB, SG18, SN8) and arabinose-xylose enriched populations (SN13, SN12, SN22, SG21) as extreme chemotypes. Intraspecific variation (coefficient of variation, CV: 14.0-50.0%) substantially exceeded interspecific differences. These findings establish Tunisian Satureja as an exceptional functional fiber source and demonstrate that population-level chemical screening outperforms taxonomic classification for developing nutraceuticals targeting cholesterol reduction, glycemic control, and gut microbiome modulation.