The L* value (lightness) of the extrudates increased with an increase in temperature from 140 °C to 180 °C, and decreased with an increase in MC of feed material from 14% to 18%, and slightly with screw speed (Table 1). The reduction in whiteness of the extrudates with increased moisture content was due to their decreased expansion ratio and increased bulk density (manifested as less puffed) product which minimises thermal exposure to pigments and retains the colour in the product.
Moisture content