Structural, rheological and functional characterization of the polysaccharides extracted from six varieties of Psidium guajava L

Limited information is available on polysaccharides derived from Psidium guajava L. fruits. In this study, polysaccharides were extracted using a hot-water method from six Tunisian guava varieties. The Ruby Supreme (RS) variety showed the highest yield (9.12%), total sugar content (90.73%), and molecular weight (212 kDa), while the L-49 variety showed the lowest yield (5.91%) and the HKP variety the lowest Mw (112 kDa). FTIR analysis revealed no significant structural differences among varieties, while monosaccharide composition showed galacturonic acid (GalA) as the predominant component (range 29.0–34.3%). DSC and TGA/DTG demonstrated good thermal stability of all extracts. All polysaccharides exhibited shear-thinning behavior (n = 0.11–0.71) and weak gel-like properties (G′ > G″). Interestingly, RS showed lower viscoelasticity (G′ = 2.42 Pa) than L-49 (G′ = 5.88 Pa) despite its higher Mw, suggesting that conformation plays a critical role beyond molecular weight. Functional properties were concentration-dependent and varied moderately among varieties. Overall, these findings highlight the influence of guava variety on polysaccharides properties and suggest their potential as food texturizing agents. Graphical abstract