Ultrasound-Assisted Sequential Extraction of Water and Alkali Soluble Proteins From Faba Bean and Pea Varieties and Their Techno-Functional Properties

Plant proteins have emerged as key components in modern food innovation. Protein extraction from legumes is well established commercially; however, studies on variations in crop varieties that can significantly affect extraction yields and functional properties are scarce. This study therefore investigates the impact of four pea (‘CARRINGTON’, ‘KARIOKA’, ‘ORCHESTRA’ and ‘MANTARA’) and eight faba bean varieties (‘AUGUSTA’, ‘IRENA’, ‘TUNDRA’, ‘VESPA’, ‘CARTOUCHE’, ‘FANFARE’, ‘LYNX’ and ‘TIFFANY’) on protein recovery and techno-functional characteristics. It compares conventional extraction (CE) and ultrasound-assisted extraction (UAE) using sequential isolation of water- and alkali-soluble proteins. All faba bean varieties (25.29%–30.37%) had significantly higher protein content than the pea varieties (17.72%–19.99%). UAE resulted in higher average protein recovery (68.92%) than CE (58.50%). However, UAE water-soluble extracts had lower average protein content (62.53%) than CE (76.56%), with the same pattern in alkali-soluble extracts (UAE: 61.48%; CE: 76.16%). Functional properties improved with UAE: WAC and OAC of water-soluble fractions increased 1.75- and 1.24-fold over CE; alkali-soluble WAC rose 1.52-fold. In gelling, four UAE faba bean and three pea varieties gelled at 14% versus 16% for CE. UAE resulted in proteins with higher elastic (G′) and viscous (G″) modulus compared with CE. Second-derivative FTIR analysis of the amide I region showed clear alterations in protein secondary structure. SEM imaging revealed ruptured, disintegrated surfaces in UAE residues versus CE. This study verifies that ultrasound promotes pea and faba bean protein extraction and functionality.