Influence of the extrusion process on the technological properties of hydroxypropylated cross-linked cassava starch

Abstract

Native cassava starch shows limited technological performance, due to considerable cohesiveness and sensitivity to mechanical shear, low pH values and high temperatures. One alternative to overcome these limitations is hydroxypropylation cross-linking, but high temperature/high pressure processes can change the potential applications of these starches. The aim of this study was to analyze the influence of the extrusion process, as a pre-gelatinization method, on the technological properties of hydroxypropilated cross-linked cassava starch. The starch was pre-gelatinized according to a central composite design with two independent variables (x1=die temperature; and x2= moisture content). The dependent variables analyzed by Re- sponse Surface Methodology were swelling power and solubil- ity (at 50, 70 and 90 °C), cold viscosity, peak viscosity, break- down, final viscosity, setback, hardness, fracturability, elastici- ty, cohesiveness, gomositivity, mastigability and resilience, and showed that the independent variables influenced the quality of the pre-gelatinized products with respect to the peak viscosity and cohesiveness (P<0.05). The thermal properties of the hydroxypropilated cross-linked cassava starch and the trials with the extreme levels of the independent variables were also evaluated. Of the independent variables, the moisture content had the greatest effect on the quality of the pre-gelatinized and hydroxypropilated cross-linked cassava starch.