Soy peptide aggregates formed during hydrolysis reduced protein extraction without decreasing their nutritional value

Area of Science:

• Food Science
• Protein Chemistry
• Biochemistry

Background:

• Enzymatic hydrolysis of soy protein isolates (SPI) can lead to significant protein loss through aggregation.
• Understanding the mechanisms behind aggregate formation is crucial for optimizing SPI processing.

Purpose of the Study:

• To investigate the formation and characteristics of insoluble peptide aggregates during SPI hydrolysis.
• To explore the influence of heating on aggregate formation and properties.
• To evaluate the in vitro digestion and potential applications of these aggregates.

Main Methods:

• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to analyze protein and peptide components.
• Amino acid analysis to determine the composition of aggregates.
• In vitro digestion assays using pepsin and pancreatin.
• Antioxidant activity assays.

Main Results:

• Insoluble aggregates formed during hydrolysis consist of aggregated peptides, driven by hydrophobic interactions.
• Heating enhances aggregation through hydrophobic forces and disulfide bonds, involving glycinin subunits.
• Aggregates are resistant to pepsin but highly degradable by pancreatin, releasing antioxidant peptides.
• The aggregates contain a high proportion of essential amino acids.

Conclusions:

• Insoluble peptide aggregates from SPI hydrolysis are formed via hydrophobic interactions and disulfide bonds, with heating accelerating the process.
• These aggregates, rich in essential and antioxidant amino acids, demonstrate potential as functional food ingredients.
• The findings suggest utility as protein supplements or active delivery systems, leveraging their unique digestion properties.