Optimization of Ultrasound-assisted Extraction of Fenugreek Seed Protein and Evaluation of Its Structural, Functional Properties and Antioxidant Activity

Proteins are one of the most important food constituents due to their unique functional properties and health benefits. Among plant proteins, fenugreek seed protein is of great interest due to its high content of essential amino acids. The current study was carried out to optimize ultrasound-assisted extraction of fenugreek seed protein and evaluation of its functional, structural and antioxidant properties. The optimal conditions for protein extraction were ultrasonic power of 80 W and sonication time of 28.39 min which under these conditions, the predicted extraction yield was 8.65% which was in good agreement with the experimental value (8.57%). Amide A, amides type I, II, and III bands were observed in Fourier transform infrared spectrum. The solubility was pH-dependent. The water and oil absorption capacity was 6.24 and 2.72 mL/g, respectively. The lowest (44.66%) and highest (92.49%) foaming capacities were observed at pH 4.5 and 10, respectively. The highest emulsifying capacity (84.53%) was observed at pH 10, while the lowest (54.82%) was at isoelectric point. At the constant pH, the foam and emulsion stability decreased over time. The results revealed that ultrasound can be applied effectively to reduce the time of protein extraction process from fenugreek seeds. In addition, the fenugreek seeds extracted by using ultrasound have desirable functional and antioxidant properties that make it feasible for utilization in the food industry.