engleski

Effect of the moisture content on the properties of extruded flours of different corn hybrids

The extrusion process enables the processing of different types of raw materials and obtaining finished products in a short period of time. Raw materials rich in starch and protein are most often used in the extrusion process, and one of the most popular is corn grits. The aim of this study was to examine the influence of moisture content (30 and 35%) on the properties of extruded flours of 6 different corn varieties of the Agricultural Institute Osijek. The extrusion process was performed on a laboratory single-screw extruder using the following conditions: extrusion temperature profile – 80/100/120 ˚C ; nozzle diameter – 4 mm ; screw configuration – 4:1. The following parameters were determined on the obtained extrudates, after drying at room temperature: expansion ratio, bulk density, water absorption index, water solubility index and rheological properties using a Brabender Micro- visco-amylograph. The results were compared to non-extruded corn flours. The obtained results showed that the increase in the moisture content did not significantly affect the expansion ratio and the bulk density of the extrudates. The extrusion process and the increase in moisture content significantly influenced the increase in the water absorption index and the water solubility index. Compared to non-extruded samples, almost all extruded samples had lower peak viscosity and their good stability was found when mixed at high temperatures, while non- extruded samples showed a greater retrogradation tendency.

extrusion ; corn ; moisture ; physical and rheological properties

nije evidentirano