Ultrasonic extraction of soy protein isolate: Characterization and comparison with microwave and enzymatic extraction methods

Abstract

Soy meal as an agro‐industrial by‐product produced by the soybean oil processing industry is rich in protein. To valorize soy meal, the present study was aimed at the optimization of soy protein isolate (SPI) extraction by ultrasound treatment, its characterization, and comparison with microwave, enzymatic, and conventionally extracted SPI. Maximum yield (24.17% ± 0.79%) and protein purity (91.6% ± 1.08%) of SPI were obtained at the optimized ultrasound extraction conditions of 15.38:1 (liquid–solid ratio), 51.85% (amplitude), 21.70°C (temperature), 3.49 s (pulse), and 11.01 min (time). The SPI extracted with ultrasound treatment showed a smaller particle size (27.24 ± 0.33 µm) as compared to that extracted with microwave, enzymatically, or conventional treatment. Functional characteristics, namely, water and oil binding capacity, emulsion properties, and foaming properties of ultrasonically extracted SPI were increased by 40%–50% as compared to SPI extracted with microwave treatment, enzymatically, or conventionally. Structural and thermal properties studied by Fourier‐transform infrared spectroscopy, X‐ray diffraction, and differential scanning colorimeter showed amorphous, secondary structural change, and high thermal resistance of ultrasonically extracted SPI. Increased functionality of ultrasonically obtained SPI can enhance its application in the development of various new food products. Practical Application Soybean meal is one of the richest sources of protein and has huge potential to lessen protein‐based malnutrition. Most of the studies on soy protein extraction were found to be based on the conventional methods that yield less quantity of protein. Hence, ultrasound treatment which is one of the novel nonthermal techniques has been selected for the present work and optimized for soy protein extraction. The ultrasound treatment showed significant improvement in extraction yield, proximate composition, amino acids profile, and improvement of functional properties of SPI as compared to the conventional, microwave, and enzymatic methods which proved the novelty of the work. Hence, the ultrasound technique could be used to increase the applications of SPI for developing a wide range of food products.

Response Surface Methodology (RSM) for Optimizing Protein Extraction from Housefly (Musca domestica) Larvae Fed with Toad and Its Structural Characterization

“…Therefore, the optimal MTL ratio of 1:35.0 g/mL was utilized for subsequent investigations. Remarkably, these outcomes exhibited a striking resemblance to the yield range of soy protein obtained elsewhere (range, 14.5-21.5%) [23].…”

Effects of preheat treatment and syringic acid modification on the structure, functional properties, and stability of black soybean protein isolate

“…Figure 5a shows that as the preheat temperature rises, the FC of BSPI first increased and then decreased, reaching the maximum at 70 • C (130.67%). The higher FC of BSPI is likely because of the formation of a more flexible protein structure during appropriate preheat treatment that resulted in rapid protein diffusion in the air-water interface (Das et al, 2023). When the preheat temperature reached 100 • C, the FC of BSPI100 decreased slightly owing to an increment in the degree of protein denaturation at 100 • C, protein exists in the form of polymers (Wang, Ma et al, 2023).…”