Morphological changes of blocklets during the gelatinization process of tapioca starch

Area of Science:

• Food Science
• Biochemistry
• Materials Science

Background:

• Tapioca starch granules possess unique surface structures called blocklets.
• Understanding the thermal behavior of these blocklets is crucial for food processing applications.

Purpose of the Study:

• To investigate the morphological changes of tapioca starch blocklets upon heating.
• To correlate these changes with thermal processing parameters and gel formation.

Main Methods:

• Tapioca starch hydrolysis using α-amylase and β-amylase.
• Thermal processing using a rapid visco analyzer (RVA) with four distinct programs.
• Scanning electron micrography (SEM) for morphological analysis.
• Freeze-drying for sample preparation.

Main Results:

• Spherical blocklets (27-60nm) were observed on native tapioca starch granules.
• Heating induced sequential changes: swelling at 52°C, olive-shape deformation and bead-like structures at 62°C, merging at 72°C (pasting temperature), and complete fusion with gel network formation at 95°C.
• Morphological changes were not simultaneous across all blocklets.

Conclusions:

• Tapioca starch blocklets undergo significant, temperature-dependent morphological transformations during thermal processing.
• These changes are critical for the development of starch gel networks and influence final product texture.
• The non-simultaneous nature of these changes may impact the homogeneity of starch-based food systems.