Rheology of star fruit pulp (Averrhoa carambola L.)

Abstract

Rheological properties of food fluids are useful for quality control, texture evaluation, and food structure determination. The rheological behavior is dependent on the size, form and concentration of solids in suspension and the system structure. Star fruit (Averrhoa carambola L.) pulp was obtained from the crude fruit and treated enzymatically, pasteurized and homogenized at 11000 rpm for 2 min and 22000 rpm for 5 min. The pulp presented Newtonian characteristics with R2 values greater than 0.98. Enzymatic treatment under 55°C for 1 h reduced the crude pulp viscosity from 1.84 to 1.22 mPa·s. Pasteurization under 100°C for 10 min increased the viscosity at around 26% in relation to the crude pulp, resulting in a turbid and homogeneous product. To evaluate the influence of the insoluble solids, filtration or concentration to 50% from the initial volume were carried out using laboratory procedures. Filtration of the pasteurized pulp promoted a viscosity decrease of 60% while concentration increased the viscosity from 2.28 to 7.98 mPa·s. © Appl. Rheol.