Structural and functional modifications of soluble dietary fiber from pea fiber residues induced by extrusion-spray modification.

Pea fiber residue, a by-product of pea starch and protein extraction, is rich in dietary fiber, most of which is insoluble. An extrusion-spray (ES) modification was developed to increase the content of functionally valuable soluble dietary fiber (SDF). This technique used a reverse-threaded section in a twin-screw extruder to increase pressure without raising the temperature, thereby promoting the conversion of insoluble fiber to SDF. This increased the SDF content from 2.65% to 10.66%, accompanied by significant increases in the levels of functional monosaccharides (arabinose: 45.24%, mannose: 9.53%). The treatment induced a concave morphology and reduced crystallinity to 17.17%. These structural changes exposed polar groups within the SDF matrix, thereby enhancing hydrophilicity and functional properties. Antioxidant properties increased 1.85-fold, resulting in maximum adsorption capacities for cholesterol and bile salts of 9.33 and 286.53 mg/g, respectively. These findings demonstrate the efficacy of extrusion-spray techniques for the valorization of pea-processing by-products.