Optimisation of extrusion variables for the production of corn snack products enriched with defatted hemp cake

Abstract

The effects of defatted hemp cake added to corn grits (at ratios of 0, 5, and 10% DM), the moisture content of the mixtures (15, 20, and 25%) and the temperature in the extruder ejection zone (150, 165, and 180°C) on the physical properties of extruded products have been investigated. Statistical optimisation of investigated extrusion conditions using the response surface methodology was performed. The hemp cake was completely defatted by means of a supercritical CO2 extraction. The extrusion was performed on a laboratory single screw extruder and regulated by the following parameters: Temperature in the dosing and compression zone (120 and 150°C), screw compression ratio (4 : 1), round die (4 mm). The change of extrusion process conditions significantly affected the physical properties of produced snacks. The expansion ratio ranged between 1.38 and 3.11, bulk density between 0.14 and 0.49 g/cm3, hardness between 18.15 and 70.62 N, fracturability from 3.65 to 10.38 mm, and the total colour change between 3.25 and 24.73.