Analytical rheology as a tool for the structural investigation of citrus pectin

• Published in: Journal of texture studies 2024-04, Vol.55 (2), p.e12828-n/a
• Main Authors: Asimakopoulou, Evdoxia, Goudoulas, Thomas, Andreadis, Ioannis I., Fatouros, Dimitrios G., Ahmad, Mehraj, Vasiliadou, Chrisi, Theocharidou, Athina, Ritzoulis, Christos
• Format: Article
• Language: English
• Subjects: citrus; low methoxyl pectin; pectin; polysaccharide configuration; rheology; temperature cycling
• ISSN: 0022-4901; 1745-4603
• DOI: 10.1111/jtxs.12828

Rheological analysis of citrus pectin at pH 3 and 7 elucidates its structural dynamics, revealing distinct behaviors influenced by pH. At pH 3, pectin exhibits shear‐thinning, with solvent‐independent unified rheological profiles identifying three concentration regimes: 0.5%–1.5%, 2%–3%, and 3.5%–4%. These regimes, alongside Cox–Merz superpositions, outline the semi‐dilute (c*) and concentrated (c**) transitions at 1.5%–2% and 3%–3.5%, respectively. Moreover, a Morris equation exponent of 0.65 indicates flexible, mobility‐restricted macromolecules. Conversely, at pH 7, increased viscosities and Morris plot linearity for p = .1 suggest rigid chain behavior due to electrostatic repulsion among ionized acidic groups. This rigidity leads to concentration‐dependent self‐assembly structures that diverge from expected unified rheological profiles, a deviation amplified by heating–cooling cycles. This study clarifies the impact of pH on citrus pectin's rheology and emphasizes the intricate relationship between polymeric chain rigidity, self‐assembly, and viscosity. By providing a refined understanding of these mechanisms, our findings contribute to the broader field of polysaccharide research, offering insights critical for developing and optimizing pectin‐based applications in various industries. Determination of polymer chain rigidity from rheological data.