Effect of particle size on rheological properties of jaboticaba pulp

Abstract

Particle size (PS) influence on rheological properties of jaboticaba pulp was evaluated, and the effect of a narrower particle size distribution (PSD) when compared to the whole pulp was observed. Particles separated from fresh pulp were wet sieved and reconstituted to serum at the same fraction as whole pulp. SEM analysis and oscillatory measurements of reconstituted samples showed that PS exerted a strong influence on rheological-structural behavior. Increasing PS from 64 up to 550 μm promoted a rise of rheological properties of reconstituted pulps, being that the viscosity increased linearly from 0.06 to 0.40 Pa s. However, pulps with larger particles showed an abrupt decay of the steady state properties because of the sedimentation promoted by the instability of the internal network due to shear. The conditions of low deformation assays did not disturb the system stability, allowing the determination of the limit of linearity of all samples. The comparison of rheological behavior between whole pulp and reconstituted samples with similar mean diameters showed that the broader PSD of the initial pulp led to a less viscous and structured suspension, indicating that not only PS, but mainly the PSD influences the rheological behavior of suspensions.