title: Rheological and interfacial properties at the equilibrium of almond gum tree exudate (Prunus dulcis) in comparison with gum arabic.
abstract: Almond gum contains an arabinogalactan-type polysaccharide, which plays an important role in defining its interfacial and rheological properties. In this study, rheological and interfacial properties of almond gum and gum arabic aqueous dispersions were comparatively investigated. The interfacial tension of almond gum and gum arabic aqueous dispersions was measured using the pendant drop method in hexadecane. The asymptotic interfacial tension values for almond gum were significantly lower than the corresponding values measured for gum arabic, especially at high concentration. Rheological properties were characterized by steady and oscillatory tests using a coaxial geometry. Almond gum flow curves exhibited a shear thinning non-Newtonian behavior with a tendency to a Newtonian plateau at low shear rate, while gum arabic flow curves exhibited such behavior only at high shear rate. The influence of temperature (5-50  ℃) on the flow curves was studied at 4% (m/m) gum concentration and the Newtonian viscosities at infinite and at zero shear rate, for gum arabic and almond gum, respectively, were accurately fitted by an Arrhenius-type equation. The dynamic properties of the two gum dispersions were also studied. Both gum dispersions exhibited viscoelastic properties, with the viscous component being predominant in a wider range of concentrations for almond gum, while for gum arabic the elastic component being higher than the elastic one especially at higher concentrations.The rheological and interfacial tension properties of almond gum suggest that it may represent a possible substitute of gum arabic in different food applications.
authors.affiliation: Food Preservation Laboratory, High Institute of Food Industry, Tunis, Tunisia nesrinemahfoudhi@yahoo.fr.
authors.forename: Nesrine
authors.initials: N
authors.lastname: Mahfoudhi
authors.affiliation: Department of Industrial Engineering, University of Salerno, Fisciano (SA), Italy.
authors.forename: Mariarenata
authors.initials: M
authors.lastname: Sessa
authors.affiliation: ProdAl scarl - Centre of Competence on Agro-Food Production, University of Salerno, Fisciano (SA), Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Ferrari
authors.affiliation: Food Preservation Laboratory, High Institute of Food Industry, Tunis, Tunisia.
authors.forename: Salem
authors.initials: S
authors.lastname: Hamdi
authors.affiliation: Department of Industrial Engineering, University of Salerno, Fisciano (SA), Italy ProdAl scarl - Centre of Competence on Agro-Food Production, University of Salerno, Fisciano (SA), Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Donsi
mesh_terms: D005503:Food Additives / Q000737:chemistry; D005685:Galactans / Q000032:analysis; D006170:Gum Arabic / Q000737:chemistry*; D016014:Linear Models; D008962:Models, Theoretical; D053149:Plant Gums / Q000737:chemistry*; D000068181:Prunus dulcis / Q000737:chemistry*; D012212:Rheology; D013696:Temperature; D014783:Viscosity
chemical_list: D005503:Food Additives; D005685:Galactans; D053149:Plant Gums; D006170:Gum Arabic; C005653:arabinogalactan
keywords: Almond gum; gum arabic; interfacial tension; rheological properties