Enzymatic hydrolysis of extruded‐expelled soy flour and resulting functional properties

Abstract

AbstractLimited hydrolysis (4% degree of hydrolysis) of extruded‐expelled soy flour protein (protein dispersibility index=21) that was poor in solubility and other functional properties was evaluated at pilot‐plant scale (5 kg of flour) with two endopeptidases and one exopeptidase. Some hydrolysates were merely spray‐dried whereas others were jet‐cooked at 104°C for 19 s before spray‐drying. Solubility, emulsification capacity and stability, foaming capacity and stability, apparent viscosity, and sensory attributes were then characterized. The type of protease used and hydrothermal cooking affected functional and sensory properties. Protein solubility modestly increased with hydrolysis and jet cooking, but emulsification capacity decreased on hydrolysis and was not restored with hydrothermal cooking. Emulsion stability improved in the endopeptidase hydrolysates, but not in the exopeptidase hydrolysates. The foaming capacities of the hydrolysates for both types of enzymes were better than for the unhydrolyzed control. Highly stable foams were obtained after hydrolyzing with exopeptidase and hydrothermal cooking. Ten percent protein hydrolysate dispersions showed large losses in consistency coefficient apparent viscosity, which increased significantly with hydrothermal cooking only for the unhydrolyzed control. Difference‐from‐control sensory evaluation indicated that both jet‐cooked and non‐jet‐cooked enzyme hydrolysates were different from unhydrolyzed controls.