Modification of sweet potato (Ipomoea batatas Lam.) residues soluble dietary fiber following twin-screw extrusion

Abstract

Effect of twin-screw extrusion on soluble dietary fiber (SDF) from sweet potato residues (SPRs) were investigated using optimized conditions, at screw speed of 180 rpm, feed rate at 17 Hz, feed moisture at 40% and extrusion temperature at 150 °C. Extruded SDF, showed higher SDF levels (9.63%-29.25%), cholesterol and sodiumcholate adsorption capacity, radical scavenging capacity, and inhibition of digestive enzymes. Moreover, extrusion effectively reduced particle size and molecularweight of SDF, modulated monosaccharide ratios, and increased water retention capacity (WRC), oil retention capacity (ORC), swelling capacity (SC) and glucose absorption capacity (GAC). Additionally, scanning electron microscopy (SEM) demonstrated decomposition of macromolecules of SDF to smaller fractions and formation of a porous morphology following extrusion. Furthermore, the extruded SDF increased thermal stability as determined by differential scanning calorimetry (DSC). Overall, the SDF from SPRs with improved functional and physiochemical properties could be used as a functional additive in diverse food products.

Keywords: Dietary fiber; Extrusion; Modification; Sweet potato residues.