Enzymatic extrusion processing of oat protein concentrates: Structural, functional, and nutritional properties

This study produced oat protein concentrates (OPCs) from pregelatinized whole oat flour via enzymatic extrusion hydrolysis and evaluated their composition, structure, and functionality. OPCs obtained by high thermal α-amylase (Thr-NDFOPC) exhibited the highest protein content (58.78 %), followed by medium α-amylase (Med-NDFOPC) (52.02 %) and conventional enzymatic hydrolysis (Con-NDFOPC) (44.08 %). Structural analyses (FTIR, CD, SEM) showed significant alterations in secondary conformation, surface roughness, and porosity, particularly in Thr-NDFOPC, indicating partial unfolding and disruption of protein networks. Functionally, OPCs displayed limited solubility at neutral and acidic pH but improved values under alkaline conditions, with Con-NDFOPC reaching nearly 60 % solubility at pH 9. Water- and oil-holding capacities ranged from 1.90 to 2.97 g/g and 2.48-2.57 g/g, respectively, while emulsifying activity and stability ranged from 21.27 and 26.89 m²/g and 37.09-47.36 min, respectively. Subsequent ethanolic defatting at 65 °C further increased the protein concentration to 64.69 % in Con-DFOPC, 72.55 % in Med-DFOPC, and 74.88 % in Thr-DFOPC, and intensified structural disintegration, resulting in reduced solubility but enhanced hydration (3.19-3.75 g/g), oil-holding capacity (3.28-3.82 g/g), and emulsification capacity (25.27-34.55 m²/g). These results highlight enzymatic extrusion hydrolysis as a scalable method for producing OPCs with tailored structural and functional properties for food applications.