Multiscale analysis of structure development in expanded starch snacks

Area of Science:

• Food Science
• Materials Science
• Physical Chemistry

Background:

• Starchy snack foods like keropok develop a solid foam structure during expansion.
• The glass transition and boiling line intersection hypothesis by Kokini and coworkers suggests optimal expansion conditions.

Purpose of the Study:

• To perform a multiscale analysis of the food structuring process during the expansion of starchy snacks.
• To investigate the validity of Kokini's hypothesis regarding optimal expansion at the intersection of glass transition and boiling lines.

Main Methods:

• Utilized time scale analysis from physical transport phenomena.
• Employed the scale separation map (SSM) within a multiscale simulation framework.
• Used a supplemented state diagram (SSD) to depict phase and glass transition lines.
• Developed and applied a multiscale simulation model for bubble expansion.

Main Results:

• Time scale analysis results plotted on the SSD provided insight into dominant physical processes.
• The SSM aided in constructing the multiscale simulation model.
• Simulation results on the SSD indicated Kokini's hypothesis is qualitatively true but requires refinement.
• Optimal bubble expansion occurs where the boiling line (4 bar gas pressure) intersects the isoviscosity line (10^6 Pa.s), parallel to the glass transition line.

Conclusions:

• The hypothesis regarding optimal expansion at the glass transition and boiling line intersection needs refinement.
• Optimal moisture content for bubble expansion is determined by the intersection of the boiling line at 4 bar and the critical viscosity isoviscosity line.