Resistant starch production from mango starch using a single-screw extruder

Resistant starches were prepared from mango starch by extrusion. An experimental design with independent variables temperature, screw speed and moisture content produced 20 samples that were studied to determine the effect of these variables on resistant starch (RS) content, water absorption index (WAI) and water solubility index (WSI). RS content was affected by moisture content and temperature. Screw speed and temperature also influenced RS content, the highest level (97 g kg^-1) being obtained at low screw speed and high temperature, this pattern can be associated with a longer residence time, which gives rise to more opportunity for amylose chain association. The regression model fitted to the RS experimental results showed a good correlation coefficient (0.80). When moisture content and temperature decreased, WAI increased (105-142 g kg^-1), but low WAI values (70-77 g kg ^-1) were obtained at moisture contents between 200 and 300 g kg ^-1 and high temperatures (140-150°C). When moisture content and temperature increased, WSI increased (222-332 g kg^-1), but at high temperature value (120°C) assayed and the lowest moisture content (150 g kg^-1), WSI also increased. In the range of moisture contents tested and at low temperatures, only partial gelatinisation occurred and low solubility was obtained.