Modifications of physicochemical, functional, structural, and nutritional properties of a field bean protein isolate obtained using batch and continuous ultrasound systems

Abstract

This study aimed to investigate the effect of ultrasound (US) treatment on improving the yield and the physicochemical, functional, structural, and nutritional properties of a protein isolate from germinated field bean flour at different conditions such as 100 and 200 W at 5, 15, 25, and 35 min. Field bean is an underutilized crop with more protein content and an alternative to animal protein, thus ensuring global food security, responsible consumption, and the well-being of consumers, which is in line with the sustainable development goals (SDGs) 2, 3, 7, 12, and 13. US treatment at 25 min and 200 W gave the best result for all the properties. Upon 25 min of sonication at 200 W, there was an increase in the protein yield, foaming ability, foam stability, emulsion activity index, emulsion stability, solubility, ζ potential, and in vitro protein digestibility from 34.33% to 59.15%, 73.11% to 110.12%, 81.44% to 90.43%, 6.92 to 13.47 m² g⁻¹, 59.97 to 104.74 min, 56.29% to 73.82%, −9.92 mV to −17.5 mV, and 94.47% to 96.37%, respectively. Moreover, a decrease in the size of particles from 1766 nm to 294.1 nm in comparison to untreated samples using green technology helps in achieving clean energy and decreases extraction time. Water holding capacity and oil holding capacity increased by 52.3% and 51.8%, respectively, after 15 min of US at 200 W. The change in the microstructure of proteins because of the US treatment was analysed using SEM. FTIR analysis confirmed the changes in the secondary structures of proteins. The physical changes caused by acoustic cavitation resulted in the partial denaturation of proteins, which was shown by an increase in their surface hydrophobicity and, thus, functionalities. Outcomes of this work demonstrated that US-assisted protein extraction increased yield and adjusted characteristics to meet the needs of the food sector, indicating a possibility for industrial use and contributed to the accomplishment of SDGs 2, 3, 7, 12, and 13.