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. 2015 Oct;52(10):6218-29.
doi: 10.1007/s13197-014-1700-4. Epub 2015 Jan 18.

Gamma irradiation of corn starches with different amylose-to-amylopectin ratio

Kok-Heung Chung  1 , Zainon Othman  2 , Jau-Shya Lee  1
Affiliations

Gamma irradiation of corn starches with different amylose-to-amylopectin ratio

Kok-Heung Chung et al. J Food Sci Technol. 2015 Oct.

Abstract

Corn starches with different amylose-to-amylopectin ratio (waxy, normal, Hylon V, and Hylon VII) were treated with five doses of gamma irradiation (1, 5, 10, 25, and 50 kGy). The effects of gamma irradiation on the physicochemical properties of starch samples were investigated. Waxy samples showed an increase of amylose-like fractions when irradiated at 10 kGy. The reduction in apparent amylose content increased with amylose content when underwent irradiation at 25 and 50 kGy. Low amylose starches lost their pasting ability when irradiated at 25 and 50 kGy. Results from thermal behavior and pasting profile suggested that low level of cross-linking occurred in Hylon VII samples irradiated at 5 kGy. Severe reduction in pasting properties, gelatinization temperatures and relative crystallinity with increasing irradiation intensity revealed that waxy samples were affected more by gamma irradiation; this also indicated amylopectin was the starch fraction most affected by gamma irradiation. Alteration level was portrayed differently when different kind of physicochemical properties were investigated, in which the pasting properties and crystallinity of starches were more immensely influenced by gamma irradiation while thermal behavior was less affected. Despite the irradiation level, the morphology and crystal pattern of starch granules were found remain unchanged by irradiation.

Keywords: Crystallinity; Gamma irradiation; Morphology; Pasting properties; Thermal behavior.

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Figures

Fig. 1
Fig. 1
The absorption spectra of starch-iodine complex for all starches
Fig. 2
Fig. 2
DSC thermograms of native untreated corn starches (waxy, normal, Hylon V, and Hylon VII)
Fig. 3
Fig. 3
Pasting profiles of starches irradiated using different doses
Fig. 4
Fig. 4
X-ray diffraction spectra for corn starches with different amylose-to-amylopectin ratio
Fig. 5
Fig. 5
a Morphology of low amylose starch granules irradiated using different doses. b Morphology of high amylose starch granules irradiated using different doses
See this image and copyright information in PMC

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