Molecular interactions and functionality of a cold-gelling soy protein isolate

Area of Science:

• Food Science
• Protein Chemistry
• Materials Science

Background:

• Soy protein isolate (SPI) is a versatile ingredient, but its thermal and cold-set gelation properties can be inconsistent.
• Understanding the protein interactions governing SPI functionality is crucial for ingredient development.

Purpose of the Study:

• To optimize thermal denaturation conditions for soy protein isolate (SPI).
• To investigate the role of protein concentration, disulfide bonds, and hydrophobic interactions in SPI gelation.
• To develop a powdered SPI ingredient with improved and consistent heat stability and cold-set gel functionality.

Main Methods:

• Thermally denaturing SPI at 8% protein concentration for 3 hours at 95°C.
• Assessing reconstituted powder properties, including heat stability and cold-set gel formation.
• Investigating the role of disulfide bonds using iodoacetamide and hydrophobic interactions using urea and DTT.

Main Results:

• Denaturation at 8% protein yielded a powder with improved heat stability and cold-set gel functionality compared to control SPI.
• Low protein concentration (3%) during initial heating significantly reduced final viscosity and gelling ability, even after reheating.
• Disulfide bond formation is essential for network formation, while hydrophobic interactions contribute significantly to gel strength.

Conclusions:

• Optimal thermal denaturation of SPI requires a critical protein concentration (8%) to facilitate intermolecular disulfide bond formation.
• This optimized process yields a powdered SPI ingredient with consistent and enhanced cold-set and thermal gelation properties.
• The findings provide insights into controlling protein-protein interactions for improved food ingredient functionality.