Bulk and interfacial behaviour of caseinoglycomacropeptide (GMP)

Area of Science:

• Food Science and Technology
• Biophysical Chemistry
• Protein Chemistry

Background:

• Caseinoglycomacropeptide (GMP) is a milk-derived glycopeptide with potential health benefits.
• GMP's functional properties are influenced by its behavior in solution and at interfaces.
• Understanding GMP's physicochemical properties is crucial for its application in functional foods.

Purpose of the Study:

• To characterize Caseinoglycomacropeptide (GMP) at the air-water interface.
• To investigate the self-assembly of GMP in solution as a function of pH.
• To correlate interfacial behavior with solution self-assembly properties.

Main Methods:

• Dynamic light scattering (DLS) for solution self-assembly.
• Tensiometry and surface dilatational rheology for interfacial properties.
• Measurements conducted at pH 4, 5, and 7.

Main Results:

• GMP exhibited higher surface pressure at pH 5 compared to pH 7.
• Complex self-assembly behavior was observed near GMP's isoelectric point (pI) at pH 4.
• Adsorption rate (K(ads)) increased with concentration, while rearrangement rate (K(r)) decreased due to steric hindrance.
• K(r) was higher at pH 5 due to reduced electrostatic interactions.

Conclusions:

• GMP's interfacial and self-assembly properties are significantly influenced by pH and concentration.
• Electrostatic interactions and steric effects play critical roles in GMP's behavior.
• These findings provide insights into optimizing GMP's use in food applications.