Investigating the crystalline structure and structural heterogeneity of starch granules using polarization-based...

Area of Science:

• Carbohydrate chemistry
• Materials science
• Biophysics

Background:

• Starch structure dictates its properties for food processing and industrial applications.
• Understanding crystalline distribution within starch granules is essential for optimizing starch utilization.
• Current models require refinement regarding the interplay of crystalline and amorphous regions.

Purpose of the Study:

• To investigate the crystalline structure of starch granules at the Maltese cross level.
• To quantify crystalline heterogeneity and its impact on enzymatic hydrolysis.
• To explore the role of amylose in disrupting starch crystal alignment.

Main Methods:

• Utilized custom-built polarization-based quantitative phase microscopy with digital holography.
• Employed a multimodal polarization microscope for detailed granule analysis.
• Performed in situ enzymatic hydrolysis and digestion assays.

Main Results:

• Observed crystalline regions on granule sides with non-crystalline material extending radially.
• Quantified crystalline heterogeneity, showing significant birefringence intensity variations (25-50% maize, 13-25% potato).
• Demonstrated asynchronous granule disruption during enzymatic breakdown due to structural complexity.

Conclusions:

• Amylose significantly disrupts crystal alignment, contributing to low overall starch crystallinity.
• Crystalline heterogeneity leads to varied susceptibility to enzymatic degradation.
• Digital holographic quantitative phase microscopy is a valuable tool for detailed starch structure analysis.