# Inter- and Intraspecific Variability in Non-Starch Polysaccharide Composition of Satureja Species from Tunisia: Implications for Functional Food Development

## TL;DR

This study explores the fiber composition of Tunisian Satureja plants, revealing high levels of non-starch polysaccharides that could be used in functional foods for health benefits.

## Contribution

The study provides the first detailed NSP profiling of Tunisian Satureja species, showing high variability and potential for functional food development.

## Key findings

- Some Satureja populations have over 50% soluble fiber, with SG4 reaching 79.7%.
- Uronic acids dominate the NSP composition, indicating pectin-rich cell walls.
- Chemical variation within species is greater than between species, suggesting population-level screening is more effective for functional food development.

## Abstract

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.