Influence of temperature, calcium and sucrose concentration on viscoelastic properties of prosopis chilensis seed gum and nopal mucilage dispersions

Abstract

Viscoelastic properties of two nontraditional hydrocolloid dispersions were evaluated. Prosopis chilensis seed gum was evaluated based on temperature (5-80 degrees C) and added CaCl2 (0.07%), whereas nopal mucilage was evaluated based on temperature (5-80 degrees C) and sucrose concentration (0-20%). Viscoelasticity was tested by the small strain oscillatory shear test; storage modulus (G), loss modulus (G) and tan were reported. Prosopis chilensis and nopal dispersions behaved as weak gels (G'>G'') regardless of experimental condition. Raising temperature from 20 to 80 degrees C significantly increased G'. The gel structure was strengthened by adding CaCl2 and G' increased at 40 degrees C. The sucrose effect depended on concentration and temperature; at low sucrose concentrations, G' modulus increased regardless of temperature level, but at high concentrations, it decreased at temperatures >40 degrees C. In conclusion, nopal and Prosopis chilensis dispersions show weak gel structure regardless of experimental condition. G increases as temperature increases, and these dispersions could be suitable for food applications requiring heat tolerance.