Influence of polysaccharides on the rheology and stabilization of α-pinene emulsions.
This work focuses on the need to include polysaccharides in a slightly concentrated O(α-pinene)/W emulsion, formulated with amphiphilic copolymers as emulsifiers. Rheology, laser diffraction and multiple light scattering were the main techniques used to assess the performance of gellan gum, xanthan gum and a mixture of both hydrocolloids as stabilizers. Small amplitude oscillatory shear results were consistent with the existence of three distinct microstructures and relaxation mechanisms, which depended on the hydrocolloid system used. The mechanical spectrum of the emulsion containing both polysaccharides signalled the occurrence of thermodynamic incompatibility between the two. Flow curves fitted to the Carreau-Yasuda model demonstrated a negative synergistic effect between gellan and xanthan gums. The droplet size distribution was similar for these systems, which highlighted the importance of the continuous phase for emulsion stability. Multiple light scattering illustrated that creaming was practically eliminated by the incorporation of polysaccharides, coalescence being the main destabilization mechanism.
Departamento de Ingeniería Química, Facultad de Química, Universidad de Sevilla, C/Profesor García González, s/n, 41012 Sevilla, Spain.
Ma Carmen
MC
García
Departamento de Ingeniería Química, Facultad de Química, Universidad de Sevilla, C/Profesor García González, s/n, 41012 Sevilla, Spain. Electronic address: alfaro@us.es.
Ma Carmen
MC
Alfaro
Departamento de Ingeniería Química, Facultad de Química, Universidad de Sevilla, C/Profesor García González, s/n, 41012 Sevilla, Spain.
Nuria
N
Calero
Departamento de Ingeniería Química, Facultad de Química, Universidad de Sevilla, C/Profesor García González, s/n, 41012 Sevilla, Spain.
José
J
Muñoz
D000081008:Bicyclic Monoterpenes; D045703:Emulsifying Agents / Q000737:chemistry; D004655:Emulsions / Q000737:chemistry*; D039821:Monoterpenes / Q000737:chemistry*; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D012212:Rheology; D013816:Thermodynamics
D000081008:Bicyclic Monoterpenes; D045703:Emulsifying Agents; D004655:Emulsions; D039821:Monoterpenes; D011135:Polysaccharides, Bacterial; C048288:gellan gum; C005451:alpha-pinene; C002563:xanthan gum
Copolymer; Emulsion; Green solvent; Multiple light scattering; Polysaccharide; Rheology