Enhancing casein micelle dissociation in diluted skim milk systems using combined processing techniques

Area of Science:

• Food Science
• Dairy Science
• Physical Chemistry

Background:

• Casein micelles are complex colloidal structures in milk.
• Understanding casein micelle dissociation is key for modifying milk functionalities.
• Existing methods for dissociation have limitations.

Purpose of the Study:

• To evaluate casein micelle dissociation in diluted skim milk.
• To investigate the combined effects of solvent/emulsifying salt treatments and ultra-high-pressure homogenization (UHPH).
• To explore potential applications of dissociated casein systems.

Main Methods:

• Diluted skim milk solutions were treated with varying ethanol concentrations (0-60%) or emulsifying salts (sodium hexametaphosphate, sodium citrate).
• Treatments were combined with ultra-high-pressure homogenization (UHPH) at pressures ranging from 100-300 MPa.
• Casein micelle dissociation was assessed via changes in sample absorbance, particle size, and hydrophobicity.

Main Results:

• High ethanol concentrations (40-60%) at elevated temperatures (45-65°C) combined with UHPH (≥200 MPa) significantly dissociated casein micelles.
• Emulsifying salts, specifically sodium hexametaphosphate (≥1 mM) and sodium citrate (≥10 mM), also induced dissociation, enhanced by UHPH (≥200 MPa).
• Dissociation was evidenced by reduced absorbance, altered particle size distribution, and increased hydrophobicity.

Conclusions:

• Both solvent-based (ethanol) and emulsifying salt-based methods effectively dissociate casein micelles when coupled with UHPH.
• Optimized processing parameters enhance the extent of casein micelle dissociation.
• These findings suggest potential for using dissociated casein systems as functional ingredients or encapsulation agents in the food industry.