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Combining Microfluidics and Microrheology to Determine Rheological Properties of Soft Matter during Repeated Phase Transitions
Published on: April 19, 2018
How micro-phase separation alters the heating rate effects on globular protein gelation
Phanin N Leksrisompong1, Edward Allen Foegeding
1Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, NC 27695-7624, USA.
Journal of Food Science
|May 4, 2011
Summary
Heating rate and pH significantly impact protein gel properties. Faster heating produces firmer gels under micro-phase separation, while single-phase conditions show less heating rate dependence over time.
Area of Science:
- Food science and technology
- Materials science
- Biochemistry
Background:
- Protein gelation is crucial for food texture and processing.
- Understanding the influence of processing parameters like heating rate and pH is vital for controlling protein gel properties.
Purpose of the Study:
- To investigate how heating rate and pH affect the viscoelastic properties and microstructure of egg white protein and whey protein isolate gels.
- To determine the relationship between solution conditions (single-phase vs. micro-phase separated) and gel formation dynamics.
Main Methods:
- Protein solutions (egg white protein, whey protein isolate) were prepared at varying concentrations (1-7% w/v) and pH (3.0-8.5).
- Samples were heated at rates from 0.2 to 60 °C/min to a final temperature of 80 °C.
- Viscoelastic properties were assessed using small strain rheology, and microstructure was analyzed via confocal laser scanning microscopy.
Main Results:
- In single-phase conditions, faster heating rates resulted in lower initial gel rigidity, but rigidity equalized after prolonged heating.
- Under micro-phase separated conditions, faster heating rates led to firmer gels by trapping phase-separated particles.
- The observed effects of heating rate were dependent on whether the protein solution was in a single-phase or micro-phase separated state.
Conclusions:
- Protein gel firmness is influenced by heating rate, pH, and protein charge.
- High net negative protein charge leads to soluble aggregates with no heating rate effect on firmness.
- Low electrostatic repulsion results in competition between precipitation and gelation, where faster heating yields firmer gels.
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