Extruding foams from corn starch acetate and native corn starch

Area of Science:

• Materials Science
• Polymer Science
• Food Science

Background:

• Native starch foams exhibit hydrophilicity, limiting their applications.
• The cost associated with modifying starch further restricts the use of starch-based foams.

Purpose of the Study:

• To decrease the hydrophilicity and cost of starch foams.
• To investigate the effects of blending native corn starch with starch acetate and extrusion processing on foam properties.

Main Methods:

• Native corn starch was blended with starch acetate.
• Foams were produced using a twin-screw mixing extruder.
• Optimized processing parameters including native starch content, screw speed, and barrel temperature were determined.

Main Results:

• Extrusion processing significantly affected starch molecular degradation.
• The melting temperature of the extruded starch acetate/native starch foam (216°C) was higher than starch acetate (193.4°C).
• New crystalline regions were formed in the extruded foam, indicated by X-ray diffractograms.
• Optimal conditions (46.0% native starch, 163 rpm, 148°C) yielded high radial expansion, high compressibility, low specific mechanical energy, and low water absorption.

Conclusions:

• Blending native corn starch with starch acetate and employing extrusion is an effective method to reduce hydrophilicity and cost.
• Optimized processing parameters enhance key physical and mechanical properties of starch foams.
• This approach offers a viable route for expanding the applications of starch-based foams.