Interactions between carrageenans and milk proteins: a microstructural and rheological study.

Area of Science:

• Food Science
• Materials Science
• Biopolymer Science

Background:

• Carrageenan is a widely used food hydrocolloid.
• Its interaction with milk proteins influences gel properties.
• Understanding these interactions is key for optimizing food texture.

Purpose of the Study:

• To investigate the microstructural and rheological differences of gels formed by kappa-, iota-, and hybrid-carrageenan in skim milk.
• To determine the impact of carrageenan dosage on gel network formation.
• To elucidate the role of carrageenan-protein interactions in gel characteristics.

Main Methods:

• Gel preparation using kappa-, iota-, or hybrid-carrageenan at low and high concentrations in skim milk.
• Confocal laser scanning microscopy with direct immunostaining to visualize carrageenan-protein microstructure.
• Rheological measurements to characterize gel properties.

Main Results:

• Low kappa- and iota-carrageenan dosages yielded fine-stranded microstructures with emulsion-like inclusions.
• High dosages of kappa- and iota-carrageenan, and both dosages of hybrid-carrageenan, resulted in strongly flocculated microstructures.
• Carrageenan-carrageenan interactions dominated gel properties at high iota- and hybrid-carrageenan dosages, and both dosages of kappa-carrageenan.
• A low dosage of iota-carrageenan formed a barely fusible gel, suggesting a coupled network.

Conclusions:

• Kappa-, iota-, and hybrid-carrageenan interact with casein micelles in skim milk.
• The influence of these interactions on overall gel properties varies significantly with carrageenan type and concentration.
• Microstructure and dosage are critical factors determining carrageenan gel network formation and properties in milk.