Effects of whey protein concentrate, feed moisture and temperature on the physicochemical characteristics of a rice-based extruded flour

- Whey protein concentrate (WPC) was added to rice-based extruded flour.
- The extrusion conditions were manipulated to produce rapid dissolution flours.
- The addition of WPC improved the nutritional and rheological characteristics of the flours.
- The extrusion conditions allowed for the protein quality to be maintained in the final product.

The influence of whey protein concentrate (WPC), feed moisture and temperature on the physicochemical properties of rice-based extrudates has been investigated. WPC (0.64-7.36 g/100 g rice) was extruded under 5 moisture (16.64-23.36 g/100 g) and 5 temperature (106.36-173.64 °C) established by a 32 central composite rotational design. Physicochemical properties [color, porosimetry, crystallinity, water solubility and absorption, pasting properties, reconstitution test, proximate composition, amino acids, minerals and electrophoresis] were determined. WPC and feed moisture increased redness, yellowness and decreased luminosity. Feed moisture and temperature increased density and total volume pore. WPC and moisture increased crystallinity, but only WPC increased solubility and decrease the retrogradation tendency. Increasing temperature increased the viscosity of the extrudates. The addition of WPC improved the nutritional composition of the extrudates, especially proteins. It is suggested that the extrusion process positively affected the retention of most of the polypeptides chains.