Acid-thermal dextrin prepared from rice starch: structure and encapsulation properties.

Area of Science:

• Food Chemistry
• Macromolecular Science
• Material Science

Background:

• Dextrins are widely used as encapsulation agents.
• Rice starch is a common source for dextrin production.
• Understanding dextrin structure-property relationships is crucial for optimizing encapsulation.

Purpose of the Study:

• To prepare and characterize acid-thermal dextrin (ATD) from rice starch.
• To investigate the encapsulation properties of ATD fractions for cinnamaldehyde.
• To elucidate the mechanism behind the encapsulation process.

Main Methods:

• Acid-thermal treatment of rice starch using hydrochloric acid and heat.
• Fractionation of ATD based on molecular weight using HPSEC.
• Identification of dextrin fractions using HPAEC.
• Encapsulation efficiency determination for cinnamaldehyde.
• Structural analysis using solid-state NMR.

Main Results:

• Three ATD fractions (I, II, III) were obtained based on molecular weight distribution.
• Fraction II (M(w)≈10,000 Da) comprised DP=2-5, DP=6-15, and DP=25-36 chains.
• Fraction II demonstrated significant encapsulation of cinnamaldehyde, reaching 41.2 μL/g at a 3:1 molar ratio.
• Solid-state NMR confirmed a single helical V-conformation in Fraction II, proposed as the encapsulation mechanism.

Conclusions:

• ATD prepared from rice starch exhibits distinct molecular weight fractions with varying properties.
• Fraction II of ATD is an effective encapsulant for cinnamaldehyde due to its specific chain length distribution and helical structure.
• The V-conformation of ATD Fraction II plays a key role in the encapsulation of hydrophobic molecules like cinnamaldehyde.