The molecular and emulsifying properties of gum arabic (GA) and mesquite gum (MG) were characterized using asymmetrical flow field-flow fractionation connected to multi-angle light scattering and refractive index detection. Properties such as molar mass, root-mean-square radius (rrms), hydrodynamic radius (rh), conformation, apparent densities and distribution of proteinaceous matter over the whole molar mass range were determined. GA displayed a low molar mass (3.4×105g/mol), protein-poor component (population 1) and a high molar mass (1.9×106g/mol), protein-rich component (population 2). MG displayed one molar mass population with an average molar mass of 1.1×106g/mol. For both GA and MG, the conformation (rrms/rh) was increasingly spherical with increasing molar mass. However, MG had higher values of rrms/rh for a specific molar mass suggesting differences in structure between GA and MG. The protein content increased with increasing molar mass for both gums, although to a higher extent for GA. Selective adsorption, during emulsification experiments, could be observed of population 2 of GA which may be due to a combination of the higher protein content and a more flexible structure rendering it more surface active than population 1. Comparing GA and MG in terms of emulsion stability, it could be concluded that GA-stabilized emulsions have considerably higher stability against coalescence.
Nota bibliográficaFunding Information:
Professor Dr. Eduardo Jaime Vernon Carter from Universidad Autónoma Metropolitana, Unidad Iztapalapa, Mexico is acknowledged for providing the sample of mesquite gum. Financial support from the Swedish International Development Agency (Sida/SAREC) , the research council FORMAS and the Swedish research council (VR) is gratefully acknowledged. Funding for instrumentation is gratefully acknowledged from: The Royal Physiographic Society of Lund, Sweden and The Crafoord Foundation, Lund .