Table 4. Effect of extrusion parameters on the browning index.

Raw material	Extrusion conditions	Barrel temperature	Moisture	Screw speed	Reference
Sorghum and barley blend	Temperature 110–140°C Moisture 20–40% Screw speed 150–310 rpm	+	-	+	( Koa et al., 2017)
Barley varieties	Temperature 150–180°C Moisture 15–20%	+	-		( Sharma et al., 2012)
Soybean and sweet potato	Screw speed 80–140 rpm			+	( Iwe et al., 2004)
Sweet potato flour	Moisture 30–40%	+	-		( Waramboi et al., 2013)

(+) Positive effect of process parameter on product parameter, (-) Negative effect of process parameter on product parameter.