Pasting investigation, SEM observation and the possible interaction study on rice starch-pullulan combination

Area of Science:

• Food Science
• Material Science
• Biochemistry

Background:

• Starch pasting properties are crucial for food texture and processing.
• Understanding interactions between starch and hydrocolloids like pullulan is important for ingredient functionality.

Purpose of the Study:

• To investigate the effect of pullulan on the pasting properties of rice starch.
• To elucidate the mechanism behind pullulan's influence on starch gelatinization.

Main Methods:

• Rapid Visco-Analyzer (RVA) was used to measure pasting properties.
• Scanning Electron Microscopy (SEM) was employed to observe microstructural changes.

Main Results:

• Pullulan addition significantly reduced peak viscosity, trough viscosity, final viscosity, and setback of rice starch.
• A novel viscosity peak was observed in rice starch-pullulan mixtures.
• SEM revealed starch granules coated by a membrane, likely pullulan or pullulan-amylose complexes.

Conclusions:

• Pullulan modifies rice starch pasting behavior by reducing overall viscosity.
• The observed viscosity peak and SEM findings suggest pullulan inhibits starch gelatinization through granule coating and potential molecular interactions with amylose.