Structural changes of native milk proteins subjected to controlled shearing and heating

Area of Science:

• Food Science
• Protein Chemistry
• Dairy Processing

Background:

• Milk protein structure is crucial for its functionality.
• Processing methods like heating and shear can alter protein conformation.
• Understanding these modifications is key to controlling milk product properties.

Purpose of the Study:

• To investigate the impact of combined temperature and shear stress on native milk proteins.
• To determine how these simulated processing conditions affect protein structure and interactions.
• To elucidate the mechanisms behind shear-induced protein modifications.

Main Methods:

• Raw skim milk was subjected to controlled temperatures (72°C and 140°C).
• Selected shear rates (0, 500, 1000 s⁻¹) were applied during processing.
• Changes in protein secondary structure and aggregate formation were analyzed.

Main Results:

• Shear stress induced reversible or irreversible changes in milk protein secondary structure across all tested temperatures.
• At 72°C, increasing shear led to fragmentation and reformation of protein aggregates.
• At 140°C, shear enhanced protein aggregate formation via hydrophobic and thiol/disulphide interactions.

Conclusions:

• Temperature and shear stress significantly impact milk protein structure and interactions.
• Shear-induced modifications are temperature-dependent, influencing protein aggregation.
• These findings provide insights into controlling milk protein behavior during processing.