Effect of mild fractionation conditions on the composition, interfacial and emulsifying properties of water-soluble fractions from faba bean flour

Abstract

Faba beans are a promising protein source, but the functional proteins must be extracted for stable beverage emulsion development. The present study examines the impact of an aqueous-based mild fractionation on the recovery, composition, interfacial and emulsifying behaviour of protein-rich soluble fractions from faba bean flour. Mild fractionation was performed at two different centrifugation speeds (3000 rpm and 4000 rpm) for various time durations (1.5–4 min). Proximate composition revealed enhanced protein recovery at the higher centrifugation speed, with the highest protein concentration of 85.9 % obtained at 4000 rpm for 2.5 min. The speed and duration of centrifugation could be controlled to optimize the extraction and protein yield from faba bean flour. The albumin-to-globulin ratio increased after mild fractionation as the duration of centrifugation increased until a plateau was observed. Interfacial tension of the soluble fractions decreased as the duration of centrifugation increased. Emulsions prepared with 3000 rpm fractions had larger droplet sizes and destabilized rapidly, while the 4000 rpm fractions could produce stable emulsions with much smaller droplet sizes. The albumin-to-globulin ratio and the presence of various minor components (phenolics, saponins and phospholipids) had negligible effects on the emulsion stability. It was found that the higher amount of hydrophobic amino acids and higher surface hydrophobicity of the 4000 rpm fractions led to faster adsorption to the oil-water interface, which could be responsible for their better emulsion stabilization ability than the 3000 rpm fractions. The proposed mild fractionation is a sustainable approach to developing stable emulsions as it can successfully retain the native proteins with their emulsifying behavior.