A comprehensive study of the relation between structural and physical chemical properties of acacia gums

Author(s)

Grein-Iankovski, Aline ^{[1, 2]} ; Ferreira, Jose G. L. ^[1] ; Orth, Elisa S. ^[1] ; Sierakowski, Maria-Rita ^[3] ; Cardoso, Mateus Borba ^{[4, 5]} ; Simas, Fernanda F. ^{[1, 6]} ; Riegel-Vidotti, Izabel C. ^[1]

Affiliation

^[1] Univ Fed Parana UFPR, Chem Dept, Grp Pesquisa Macromol & Interfaces, CP 19081, BR-81531980 Curitiba, PR - Brazil

^[2] Univ Campinas UNICAMP, Inst Chem, CP 6184, BR-13083970 Campinas, SP - Brazil

^[3] Univ Fed Parana UFPR, Chem Dept, BioPol, CP 19081, BR-81531980 Curitiba, PR - Brazil

^[4] Brazilian Synchrotron Light Lab LNLS, CP 6154, BR-13083970 Campinas, SP - Brazil

^[5] Brazilian Nanotechnol Natl Lab LNNano, CP 6154, BR-13083970 Campinas, SP - Brazil

^[6] Univ Fed Parana UFPR, Cellular Biol Dept, BR-81531980 Curitiba, PR - Brazil

• Document type: Journal article
• Source: FOOD HYDROCOLLOIDS; v. 85, p. 167-175, DEC 2018.
• Web of Science Citations: 4

Abstract

Previously, we fully investigated the chemical and structural characteristics of two acacia gum samples. Now, the gums' physical chemical properties were investigated using zeta potential, fluorescence spectroscopy, potentiometric titration, viscometry and SAXS, and correlated to the gums's structural and self-association particularities. Since acacia gums are widely used in many food products, our aim was to elucidate the origin of the Acacia mearnsii gum (GN) properties in comparison with a commercial Acacia gum (GA). Both gums are negatively charged polyelectrolytes, nevertheless, the uronic acids in GN are stronger in view of the pK(a) of the carboxyl groups are similar to 10-25% lower than in GA. Also, the acid dissociation constant (pK(a)) for both gums, can be related to the gums aggregation behavior. The pK(a) variability is more pronounced at lower gum concentrations and an inflexion point is noted close to the critical adsorption concentration. GN presents a more pronounced self-association behavior and a higher intrinsic viscosity (0.23 dL g(-1) vs 0.13 dL g(-1)), indicating a less compact structure. The SAXS scattering profile of GA revealed two size levels, consistent with a thin ellipsoid morphology with 2.0 nm (thickness) and 12.0 nm (radius). GN, though, presented just one broad bulge, suggesting a higher dispersity level. It was demonstrated that specific variations in the gums chemical structure reflect directly on their self-assembly feature which, in turn, plays an important role on the gums intrinsic physical chemistry properties, whatever the probed length scale. (AU)

• FAPESP's process: 15/25406-5 - Organizing matter: colloids formed by association of surfactants, polymers and nanoparticles
• Grantee: Watson Loh
• Support Opportunities: Research Projects - Thematic Grants