Modification of faba bean protein isolate by high-intensity ultrasound treatment: screening of physicochemical, thermal, and structural properties

Abstract

This study aimed to investigate the impacts of high-intensity ultrasound treatments on the physicochemical, thermal, and structural properties of faba bean protein isolates (FPI). Aqueous FPI suspensions were sonicated at 20 kHz for 1, 3, 5, and 10 min. Ultrasound treatment increased the solubility of FPI at all sonicated times, with maximum solubility (89.11%) observed at the 3-min treatment. Particle size (from 370.47 to 187.87 nm) and zeta potential (from - 40.83 to - 37.17 mV) reduction (in magnitude) by sonication were observed at all studied times. The usage of ultrasound has been found to have a more pronounced antibrowning impact compared to unsonication (higher L* and b*, lower a*, C*, H*, BI, and Delta E). With the increase in sonication treatment from 0 to 3 min, the Td decreased from 103.07 to 99.58 degrees C and Delta Hd from 2.21 to 1.12 J/g, which were related to the changes in the secondary structure of proteins. Sonication changed the secondary structure of FPI, decreasing the alpha-helix, beta-turn, and random coil content, and increasing the beta-sheet for samples treated up to 3 min. Prolonged sonication increased the alpha-helices due to the extension of certain types of hydrogen bonds in the structure. The microstructural changes of FPI caused by ultrasound were further validated through observations made using a scanning electron microscope, which revealed the presence of smaller fragments. The present study indicates that the use of ultrasound has the potential to improve the functionality of FPI, hence potentially enhancing the efficacy of FPI-based food products.