Physicochemical characterization of gamma irradiated sago starch and rice starch

Ng , Jia Qin (2013) Physicochemical characterization of gamma irradiated sago starch and rice starch. Universiti Malaysia Sabah. (Unpublished)

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Abstract

In this study, sago and rice starches were subjected to gamma irradiation treatment at 5, 10, 25 and 50 kGy. Effects of irradiation on physicochemical properties of starches were Investigated. Cleavage of starch molecules by irradiation induced the formation of carboxylic acid which in turn increased the carboxyl content and reduced pH value of both starches (p<0.05). Sago starch showed greater alteration in carboxyl content and pH than rice starch. Severe degradation of amylose fractions by irradiation significantly decreased amylose content at high dosage (p<0.05), where greater reduction was showed by rice starch irradiated at 50 kGy. Rice starch (A-type polymorphic) had greater decrease in the degree of ordered structure than sago starch (C-type polymorphic). The reduction of the molecular size due to irradiation also resulting in declination of swelling power and turbidity while increased solubility of starch as irradiation dose increased (p<0.05). Sago starch showed greater reduction in swelling power than rice starch at 50 kGy (p<0.05). Syneresis was found at high irradiation doses where rice starch irradiated at 50 kGy showed highest percentage of syneresis (p<0.05). The major pasting profile parameters decreased drastically with increasing irradiation doses in both starches (p<0.05), particularly for rice starch irradiated at 50 kGy. Gelatinization temperature for sago starch increased as irradiation dose increased, while opposite trend was observed in rice starch (p<0.05). Irradiation did not affect retrogradation of sago starch (p>0.05), whereas it induced retrogradation in rice starch with increasing doses (p<0.05). The rheological study showed reduction of viscosity as irradiation doses increased for both starches. Higher irradiation dosage (25 and 50 kGy) was found to damage the gel-forming ability of starch. Microscopic observation under Scanning Electron Microscope (SEM) showed granular size reduction at higher irradiation dosage.

Item Type:Academic Exercise
Uncontrolled Keywords:gamma irradiation treatment, Scanning Electron Microscope (SEM), sago starch, rice starch, reduction of viscosity
Subjects:T Technology > TP Chemical technology
Divisions:SCHOOL > School of Food Science and Nutrition
ID Code:10054
Deposited By:IR Admin
Deposited On:05 Dec 2014 15:14
Last Modified:07 May 2015 11:54

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