On‐line rheology of pearl millet flours during extrusion: Effect of native amylose

Abstract Pearl millet is a micro‐nutrient rich crop grown in arid regions of Asia and Africa. Millet based extruded products can ensure both food and economic security amongst these malnutrition prone areas. The effect of flour crystallinity and amylose content on the rheological attributes during thermo‐mechanical processing of pearl millet cultivars was determined using on‐line rheometer during twin‐screw extrusion. The shear strain measurements indicated shear thinning behavior which was modeled using modified Power law ( R 2 > 0.8). Upon increase in moisture content and barrel temperature, the consistency index of pearlmillet flour was found to decrease. Higher amylose cultivars demonstrated higher consistency index. The flow behavior index increased with moisture and temperature. Modified Arrhenius model was used to explain the effect of temperature and moisture on consistency index. This study underlines the effect of crystallinity and amylose on the rheology of millets during extrusion. Practical applications The findings of this study shall be helpful in: determining extrusion conditions for processing whole pearl millet flours. screening varieties of pearlmillet suitable for different types of extruded products varying in degrees of polymeric modification.