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

Abstract

In this study, acid-thermal dextrin (ATD) was prepared from rice starch using hydrochloric acid in combination with heat treatment. The structure and encapsulation properties of ATD were examined. The results showed that three fractions (Fraction I, Fraction II, and Fraction III) in ATD were obtained based on the distribution of molecular weight (M(w)) in high-performance size-exclusion chromatographic (HPSEC) spectra. The Fraction II (M(w)≈10,000 Da) was identified using high-performance anion exchange chromatography (HPAEC), indicating that it consisted of three major groups: DP=2-5, DP=6-15, and DP=25-36. This distribution in chains led to good encapsulating ability of Fraction II to cinnamaldehyde (CIN) and a maximum encapsulation rate reached 41.2 μL/g (CIN/Fraction II) with a molar ratio of about 3:1. The encapsulating mechanism was proposed due to a single helical V-conformation (single resonance at 102.7 ppm) of Fraction II present and observed in solid-state NMR spectra.

Keywords: Acid-thermal dextrin; Encapsulating ability; Helical structure.