Effect of extrusion processing on techno-functional, textural and bioactive properties of whole-grain corn...

The present study investigated the effect of honey and extrusion processing parameters on techno-functional and bioactive properties of whole-grain corn flour breakfast cereals. The central composite rotatable design (CCRD) was used to plan the experiments using feed moisture (FM), extrusion temperature (ET), and honey level as process variables and sectional expansion ratio (SER), bulk density (BD), water absorption index (WAI), water solubility index (WSI), and textural hardness as response variables. The feed containing honey and whole-grain corn flour was extruded through a twin-screw extruder according to CCRD. The data were fit to the appropriate regression models based on model significance and insignificant lack of fit. The selected experiments from CCRD were considered for studying the bioactive properties, and the effect of ET and honey level on bioactive properties was determined. The results of the study indicated that FM and honey adversely affected the SER, BD, and textural hardness, while ET augmented these properties of breakfast cereals. The WAI decreased with an increase in honey level and ET during extrusion. The incremental addition of honey in the mix as well extrusion at elevated temperature led to higher WSI. The whole-grain corn flour added with 10.22% honey and extruded at 16.06% FM, and 138.07°C ET produced optimum quality breakfast cereals with 0.70 desirability. The total phenolic content of breakfast cereals decreased, and antioxidant activity and hydroxymethylfurfural content increased upon extrusion at the higher temperatures. Honey addition lowers the loss of phenolic content during extrusion and improves the antioxidant activity of breakfast cereals.