Effect of Gamma Irradiation on Molecular Structure and Physicochemical Properties of Corn Starch

• Published in: Journal of food science 2009-06, Vol.74 (5), p.C353-C361
• Main Authors: Chung, H.-J, Liu, Q
• Format: Article
• Language: English
• Subjects: Amylopectin - radiation effects; amylose; Amylose - radiation effects; Biological and medical sciences; Calorimetry, Differential Scanning; Carbohydrates; carboxylation; Chemical Phenomena - radiation effects; Chemistry, Physical - methods; corn starch; crystal structure; digestibility; dose rate; Dose-Response Relationship, Radiation; food analysis; food composition; Food engineering; Food industries; Food irradiation; Food Irradiation - methods; food processing quality; Food science; Fundamental and applied biological sciences. Psychology; gamma irradiation; gamma radiation; General aspects; Leaching; Lipids; Lipids - radiation effects; Molecular Structure; physicochemical properties; Spectroscopy, Fourier Transform Infrared; Starch - chemistry; Starch - radiation effects; Starch and starchy product industries; structural properties; Surface Properties - radiation effects; Viscosity - radiation effects
• ISSN: 0022-1147; 1750-3841
• DOI: 10.1111/j.1750-3841.2009.01159.x

Carboxyl content and amylose leaching of gamma-irradiated corn starch increased and swelling factor decreased with increasing radiation dose. The apparent amylose content decreased gradually from 28.7% for native starch to 20.9% for 50 kGy irradiated starch. The proportion of short amylopectin branch chains (DP 6 to 12) increased, while the proportion of longer branch chains (DP greater-than-or-equal 37) decreased with increasing radiation dose. The relative crystallinity and the degree of granule surface order decreased from 28.5% and 0.631 in native starch to 26.9% and 0.605 in 50 kGy irradiated starch, respectively. Pasting viscosity and gelatinization temperatures decreased with an increase in radiation dose. At a high dose (50 kGy), melting of amylose-lipid complex in DSC thermogram was not observed. The rapidly digestible starch (RDS) content slightly decreased up to 10 kGy but increased at 50 kGy. The resistant starch (RS) content slightly decreased at 2 kGy and then increased up to 50 kGy. The slowly digestible starch (SDS) content showed the opposite trend to RS content. Slower irradiation dose rate reduced carboxyl content, swelling factor, and amylose leaching. The apparent amylose content and amylopectin chain length distribution were not significantly affected by dose rate of gamma irradiation. However, the relative crystallinity and gelatinization enthalpy increased with slower dose rate. Slower dose rate decreased RDS and SDS contents, and increased RS content.