Physicochemical properties of waxy and normal maize starches irradiated at various pH and salt concentrations

Byung Ryol Baik, Jin Young Yu, Hyun Seong Yoon, Ju Woon Lee, Myung Woo Byun, Byung Kee Baik, Seung Taik Lim

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Waxy and normal maize starches of various pH values and salt contents were prepared, irradiated with gamma rays (5-20 kGy) and their molecular structure, pasting viscosity and rheological properties determined. Average molar mass and size of both waxy and normal maize starches decreased considerably by irradiation from >338.0 × 106 to <39.4 × 10 6 g/mol and from >237.5 to <125.2 nm, respectively. Adjustments of pH had little influence on the average molar mass and size of irradiated starch, whereas incorporation of salt greatly reduced the molar mass and size of irradiated waxy and normal maize starches. As the pH increased from 4 to 8, the pasting viscosity of the irradiated starches decreased from 1032 to 279 mPa s in waxy and from 699 to 381 mPa s in normal starches. Pasting viscosity of both irradiated waxy and normal starch decreased from 689 to 358 mPa s and from 327 to 184 mPa s as the salt concentration increased from 1 to 5%. The G0 of gels, determined during cooling from 90 to 10°C or storage for 8 h, decreased in irradiated waxy and normal starches by pre-conditioning at pH 8 and in irradiated waxy starches by pre-conditioning at 5% NaCl. With 5% NaCl, G' of irradiated normal maize starch during cooling increased up to the irradiation level of 10 kGy, and increased during storage for 8 h at all levels of irradiation. Incorporated salt prior to irradiation appears to induce incremental modifications in the molecular structure, rheological and retrogradation properties of starch by boosting the degradation of molecules.

Original languageEnglish
Pages (from-to)41-48
Number of pages8
JournalStarch/Staerke
Volume62
Issue number1
DOIs
Publication statusPublished - 2010 Jan

Keywords

  • Dynamic rheology
  • Irradiation
  • Normal maize starch
  • Waxy maize starch

ASJC Scopus subject areas

  • Food Science
  • Organic Chemistry

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