Microwave and Ultrasound to Enhance Protein Extraction from Peanut Flour under Alkaline Conditions: Effects in Yield and Functional Properties of Protein Isolates

• Published in: Food and bioprocess technology Vol. 10; no. 3; pp. 543 - 555
• Main Authors: Ochoa-Rivas, Ariana, Nava-Valdez, Yazel, Serna-Saldívar, Sergio O., Chuck-Hernández, Cristina
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-03-2017; Springer Nature B.V
• Subjects: Absorption; Agriculture; Amplitudes; Biotechnology; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Digestibility; Food Science; Legumes; Microstructure; Microwaves; Nitrogen; Original Paper; Peanuts; Properties (attributes); Protein structure; Proteins; Purity; Secondary structure; Solubility; Synergistic effect; Ultrasonic imaging; Ultrasound; Water absorption; Microwave; Functional properties; Peanut; Alkaline extraction; Protein isolate; Ultrasound
• ISSN: 1935-5130; 1935-5149
• DOI: 10.1007/s11947-016-1838-3

The effect of microwaves (MWs) and/or ultrasound (US) to assist alkaline extraction of peanut proteins was evaluated. Isolate extraction yields and purities were obtained as well as functional properties (water solubility and retention, fat absorption, nitrogen solubility, emulsifying activity, and foam activity and stability), in vitro digestibility, free amino nitrogen (FAN), microstructure and secondary structure. In MW-assisted treatments, power (145, 290, 435, 580, and 725 W) and time (2, 4, 6, 8, and 10 min) were evaluated, whereas in US-assisted assays, amplitude (20/100%) and time (15/40 min) were varied. For MW-assisted extraction, 725 W and 8 min yielded an extraction of 55% (100% purity), i.e., 77% more protein when compared with the control, while for US, an increase of 136% and purity of 86% was reached (100% amplitude and 15 min). The sequential use of both technologies was also evaluated, but a synergistic effect in protein extraction was not observed. In terms of functional properties, fat absorption index remained the same for both treatments whereas water absorption, foam activity, emulsifying activity (for MW), and in vitro digestibility (for MW only) improved. In the case of free amino nitrogen, a reduction of 50% for assisted peanut protein isolates was observed. Microstructure was not different among treatments, but secondary structure did change: β-sheet and nonordered structures were higher for experimental treatments compared with the traditional alkaline isolate (up to 8 and 4%, respectively). The use of MW and US favored peanut protein extraction for production of high purity isolates.