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Open AccessArticle

Effects of High-Intensity Ultrasound Pretreatment on Structure, Properties, and Enzymolysis of Soy Protein Isolate

1
Department of Food Science and Engineering, Shandong Agricultural University, Tai’an 271018, China
2
Engineering and Technology Center for Grain Processing of Shandong Province, Tai’an 271018, China
3
Jinan Fruit Research Institute, All-China Federation of Supply and Marketing Co-operatives, Jinan 250014, China
4
State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan 250353, China
*
Authors to whom correspondence should be addressed.
Fei Zhao and Xuemei Liu contributed equally to this work and are co-first authors.
Molecules 2019, 24(20), 3637; https://doi.org/10.3390/molecules24203637
Received: 4 September 2019 / Revised: 28 September 2019 / Accepted: 1 October 2019 / Published: 9 October 2019
The objective of this study was to investigate the effects of different high-intensity ultrasonication (HIU) pretreatment on the structure and properties of soybean protein isolate (SPI) as well as enzymatic hydrolysis of SPI by bromelain and antioxidant activity of hydrolysates. The HIU-treated SPI fractions showed a decrease in the proportion of α-helices and β-turns and an increase in the content of β-sheets and random coils based on Fourier-transform infrared spectroscopy. Near-infrared spectra and fluorescence spectra analyses provided support for the changes in secondary and tertiary structures of SPI after ultrasound treatment. The particle size of SPI decreased from 217.20 nm to 141.23 nm and the absolute zeta potential increased. Scanning electron microscopy showed that HIU treatment changed apparent morphology. Dynamic and static light scattering of ultrasonicated samples showed that SPI structure had changed from hard-sphere to hollow-sphere or polydisperse and monodisperse gaussian coils. HIU pretreatment significantly increased the hydroxyl-radical scavenging and the degree of hydrolysis of the SPI hydrolysates. View Full-Text
Keywords: high-intensity ultrasonication; soybean protein isolates; near-infrared spectra; ζ-potential; dynamic and static light scattering; antioxidant activity high-intensity ultrasonication; soybean protein isolates; near-infrared spectra; ζ-potential; dynamic and static light scattering; antioxidant activity
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MDPI and ACS Style

Zhao, F.; Liu, X.; Ding, X.; Dong, H.; Wang, W. Effects of High-Intensity Ultrasound Pretreatment on Structure, Properties, and Enzymolysis of Soy Protein Isolate. Molecules 2019, 24, 3637.

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