The interaction between Lactobacillus exopolysaccharide and soy protein during the fermentation process: Aggregation...

Area of Science:

• Food Science
• Biochemistry
• Microbiology

Background:

• Lactobacillus casei exopolysaccharides (CEPS) are crucial in fermented foods.
• Soy protein isolate (SPI) is a key ingredient in many food products.
• Understanding CEPS-SPI interactions is vital for optimizing fermentation processes.

Purpose of the Study:

• To elucidate the molecular mechanisms governing CEPS-SPI interactions during fermentation.
• To analyze the aggregation characteristics and binding kinetics of CEPS-SPI composites.
• To investigate the influence of CEPS concentration and pH on these interactions.

Main Methods:

• Construction of acidified CEPS-SPI composite systems.
• Analysis of aggregation characteristics.
• Investigation of binding kinetics and zeta potential.
• Dynamic force analysis during acidification (pH 7.0-4.5).

Main Results:

• CEPS concentration and pH significantly regulate CEPS-SPI interactions.
• CEPS altered key pH points for soluble complex formation (pH_φ1 and pH_max).
• Minimum solubility and zero zeta potential shifted to lower pH values.
• Three distinct phases of interaction forces were identified during acidification: van der Waals/hydrogen bonding, hydrophobic/electrostatic, and electrostatic interactions.

Conclusions:

• CEPS plays a significant role in modulating SPI's functional properties during fermentation.
• The study provides a theoretical framework for EPS-protein interactions in fermentation.
• Findings support the development of high-quality fermented soy products.