EFFECT OF MESQUITE SEED GUM ON THE RHEOLOGICAL PROPERTIES OF MIXTURES WITH ARABIC AND GELLAN GUMS

摘要

The mesquite seed gum (Prosopis sp.) represents an alternative application in the food industry, due to its structural likeness with other galactomannans used at the moment. The information about the properties of mesquite seed gum is scarce, for this is important to known the rheological properties of this biopolymer and its interactions with other polymers for seeing future applications. The aim of this work was study the rheological behavior of mesquite seed gum and their effects in arabic and gellan gum mixtures. They were prepared aqueous dispersions according to a Simplex-Centroid design, being obtained gum combinations of total concentration of 1% from mesquite-arabic, mesquite-gellan, arabic-gellan and mesquite-arabic-gellan, the pH from the dispersions were adjusted to 4, 5 and 6. The mixtures as well as the individual biopolymers were dispersed to ambient temperature, and later heated during 20 minutes at 90°C and cooling at 25°C. The rheological studies were made using an Haake RV2 viscometer. The statistical analysis showed differences (α = 0.05) among the rheologic value for mixtures at different pH. The mixtures showed a non-Newtonian behavior, type pseudoplastic flow (shear thinning) and showed high viscosities to low shears rates (100 s~(-1)) in all the cases. The tendency of mixtures with two or three components showed an antagonistic effect in the viscosity. Particularly the mesquite seed gum suffers an antagonistic effect in the viscosity when it was mixed with the arabic and gellan gums, being observed decreases from a 8 until 45%, below the control.