Preparation of crystalline starch nanoparticles using cold acid hydrolysis and ultrasonication

Hee Young Kim, Dong June Park, Jong Yea Kim, Seung Taik Lim

Research output: Contribution to journalArticle

63 Citations (Scopus)

Abstract

Waxy maize starch in an aqueous sulfuric acid solution (3.16 M, 14.7% solids) was hydrolyzed for 2-6 days, either isothermally at 40 °C or 4 °C, or at cycled temperatures of 4 and 40 °C (1 day each). The starch hydrolyzates were recovered as precipitates after centrifuging the dispersion (10,000 rpm, 10 min). The yield of starch hydrolyzates depended on the hydrolysis temperature and time, which varied from 6.8% to 78%. The starch hydrolyzed at 40 °C or 4/40 °C exhibited increased crystallinity determined by Xray diffraction analysis, but melted in broader temperature range (from 60 °C to 110 °C). However, the starch hydrolyzed at 4 °C displayed the crystallinity and melting endotherm similar to those of native starch. The starch hydrolyzates recovered by centrifugation were re-dispersed in water (15% solids), and the dispersion was treated by an ultrasonic treatment (60% amplitude, 3 min). The ultrasonication effectively fragmented the starch hydrolyzates to nanoparticles. The hydrolyzates obtained after 6 days of hydrolysis were more resistant to the ultrasonication than those after 2 or 4 days, regardless of hydrolysis temperatures. The starch nanoparticles could be prepared with high yield (78%) and crystallinity by 4 °C hydrolysis for 6 days followed by ultrasonication. Scanning electron microscopy revealed that the starch nanoparticles had globular shapes with diameters ranging from 50 to 90 nm.

Original languageEnglish
Pages (from-to)295-301
Number of pages7
JournalCarbohydrate Polymers
Volume98
Issue number1
DOIs
Publication statusPublished - 2013 Jul 11

Keywords

  • Acid hydrolysis
  • Nanocrystals
  • Nanoparticles
  • Starch
  • Ultrasonication

ASJC Scopus subject areas

  • Organic Chemistry
  • Materials Chemistry
  • Polymers and Plastics

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