The probing for nanoparticles in soybean protein isolate solutions.

Area of Science:

• Food Science
• Biochemistry
• Materials Science

Background:

• Soybean protein isolates (SPI) are widely used in the food industry.
• Understanding the behavior of SPI at a molecular level is crucial for optimizing food processing.
• Nanoparticle (NP) formation within SPI solutions can significantly impact their functional properties.

Purpose of the Study:

• To investigate the structural and behavioral differences between nanoparticles (NPs) formed from high (GN) and low (DN) molecular weight soybean protein isolates (SPI).
• To elucidate how NP properties affect their stability and behavior upon dilution.
• To provide insights into selecting appropriate SPI raw materials for extrusion processes.

Main Methods:

• Preparation and characterization of two types of SPI: high molecular weight (GN) and low molecular weight (DN).
• Analysis of nanoparticle (NP) size, shape, charge, and stability in SPI solutions using various biophysical techniques.
• Investigation of NP structural changes upon dilution via fluorescence spectroscopy and measurements on filtered samples.

Main Results:

• Both GN and DN SPI formed heterogeneous nanoparticles (NPs).
• GN NPs were larger, more compact, more stable, and more negatively charged than DN NPs.
• Dilution induced NP swelling and disassembly, with tryptophan and tyrosine residues shifting to hydrophobic environments, indicating bond disruption.

Conclusions:

• Differences in NP properties between GN and DN SPI are linked to their molecular weight and affect their behavior during processing.
• Understanding these NP characteristics is vital for predicting SPI performance in applications like extrusion.
• This research provides a basis for establishing criteria for selecting SPI raw materials in the food industry.