Thermal and Rheological Properties of the Mucilage from the Fruit of Cordia lutea

In recent years, natural gums and mucilages have been shown to be useful in the food and pharmacological industries. In this study, the mucilage of the fruit of Cordia lueta has been extracted and characterised in order to explore its potential applications. Thermogravimetric tests were used to measure the water content of this natural mucilage. Differential scanning calorimetry allowed assessing thermal transitions and thermal degradation of the samples. Steady flow rheometry was used to measure the viscosity of the samples as a function of the shear rate. Dynamic oscillatory rheometry was used to study the variation of the storage and loss modulus of the mucilage as function of the oscillatory frequency and stress. The results showed that this mucilage is a polysaccharide network that behaves as a pseudoplastic fluid. Its storage modulus is not completely independent from the oscillation frequency. In addition, the stress sweeps showed that C. lutea mucilage has a reversible stress softening behaviour. The findings reported in the present work suggest that this mucilage can be used as a rheology modifier for commercial foods and biomedical materials.