Impact of extrusion on swelling power and foam stability in mixtures of corn starch and whey protein isolate as a model system

Abstract

This study examines the impact of an extrusion process on the swelling power (SP) and the foaming stability (FS) of mixtures of corn starch (CS) and whey protein isolate (WPI). A single-screw extruder was operated with a speed of 200 rpm, feed rate of 100 g/min, extrusion temperature of 140ºC, and initial moisture content of 20%. The results show that the extrusion process significantly increased the SP of the CS/WPI mixtures at each of the heating temperatures evaluated (60, 70, 80, and 90ºC). Furthermore, a significant increase in SP was observed with the increase in temperature in most of the mixtures. The extrusion only slightly affected the foam stability of the mixtures. The results show the importance of extrusion on the interactions between CS and WPI.