Cercidium praecox brea gum arabinoglucuronoxylans: A viscosant substitute for gum Arabic?. (April 2023)

• Record Type: Journal Article
• Authors: Sznaider, Frank; Stortz, Carlos A.; Rojas, Ana M.; Navarro, Diego A.
• Is Part Of: Food hydrocolloids. Volume 137(2023)
• Publication Date: 2023-04
• Subjects: Brea gum -- Gum Arabic -- Viscosity -- Dynamic mechanical spectra -- Thermo-reversible weak gels -- Hydrophobic acetyl groups; Hydrocolloids -- Periodicals; Food additives -- Periodicals; Colloïdes -- Périodiques; Aliments -- Additifs -- Périodiques; Colloids; Food additives; Periodicals; Electronic journals; 664.06
• DOI: 10.1016/j.foodhyd.2022.108403
• Languages: English
• ISSNs: 0268-005X

Abstract

Abstract: Brea gum, obtained from the cuts made in the trunk and branches of Cercidium praecox tree, has been traditionally collected and used as a substitute of gum Arabic (GA ) in some regions of Argentina. The rheological performance of purified brea gum (BG ) in water (20 °C) was thoroughly evaluated between 1 and 35% w/v. As we previously determined, BG is composed of highly branched arabinoglucuronoxylans (1:0.44:0.16:0.22 xylose:arabinose:glucuronic acid:4- O -methylglucuronic acid molar ratio) with 2.6% of acetyl groups bound to the O -3 of the xylan backbone. The deacetylated form (DBG ) was also assayed at 10% w/v. Commercial GA was also considered for comparison. In flow assays (viscosity versus shear rate), BG (1–35%) showed pseudoplastic behavior, and higher initial thickening at very low shear rates (Newtonian viscosity, η0 ≈ 27.3–130 Pa⋅s) than 1–35% w/v GA (η0 ≈ 10–20 Pa⋅s), and 10% DBG (η0 ≈ 7 Pa⋅s). Dynamic mechanical spectra showed "solutions" for GA, and "weak-gel" type networks for BG, more frequency dependent at 35%, probably due to the lowest electrostatic repulsion at pH 3.77. Instead, 10% DBG showed a "dilute solution" spectrum. Heating and cooling ramps (5 °C/min) revealed a gelling temperature for 17.5% (24.2 °C) BG, but not for GA and DBG solutions. BG "weak-gels" were thermo-reversible. Thermal study revealed hydrophobic interactions between BG macromolecules, and hydrogen bonding between DBG macromolecules. BG macromolecules can have an extended hydrophobic (acetylated) side, absent in DBG . Like GA, rheological functionality can yield a commercial use of BG as food additive. Graphical abstract: Image 1 Highlights: Purified brea gum (BG ) (1–35% w/v) was evaluated rheologically in water at 20 °C. BG is composed of highly branched arabinoglucuronoxylans with 2.6% of acetyl groups. BG was pseudoplastic and more viscous than Gum Arabic (GA ) and deacetylated BG . BG forms "weak-gel" type network, as opposed to GA and deacetylated BG . Thermo-reversible gels with acetyl hydrophobic interactions make BG a useful additive.