Characterization of Physical Properties of Flour and Starch Obtained from Gamma-Irradiated White Rice

Abstract

Physical and structural characteristics of rice flour and starch obtained from gammairradiated white rice were determined. Pasting viscosities of the rice flour and starch, analyzed by using a Rapid Visco Analyser, decreased continuously with the increase in irradiation dosage. Differential scanning calorimetry showed that gelatinization onset, peak and conclusion temperatures of rice flour and starch changed slightly but the enthalpy change decreased significantly with increase of irradiation dosage. All irradiated starch displayed an A-type X-ray diffraction pattern like the native starch. Gel permeation chromatography showed that the blue value ratio of the first peak (amylopectin) to the second one (amylose) decreased with the increase of the irradiation dosage. The weight-average molecular weight (M w ) and gyration radius (R z ) of amylopectin analyzed by using HPSEC-MALLS-RI (high-performance size-exclusion chromatography equipped with multiangle laser-light scattering and refractive index detector) decreased gradually from 1.48610 9 (M w ) and 384.1 nm (R z ) of native rice starch to 2.36610 8 (M w ) and 236.8 nm of 9 kGy-irradiated starch. The branch chainlength distribution of amylopectins determined by HPAEC-ENZ-PAD (high-performance anion-exchange chromatography with amyloglucosidase post-column on-line reactor and pulsed amperometric detector) showed that gamma irradiation had no significant effect on the amylopectin branch chains with 13DP24 and 37DP, but produced more branch chains with 6DP12 when the irradiation dosage was less than 9 kGy. It might be deduced that gamma irradiation caused the breakage of the amylopectin chains at the amorphous regions, but had little effects on the crystalline regions of starch granules, especially at low dosage irradiation.

Functional Properties of Some Non-Conventional Treated Starches

“…Recently, information regarding starch treatment with electron beam (e-beam) in different irradiation dose range, either at low or relative high doses (0 -25 kGy) (De Kerf et al, 2001;Pimpa et al, 2007) or at very high doses (> 50 kGy) (Kamal et al, 2007;Shishonok et al, 2007) were reported. The studies concerning the effects of ionizing radiation were performed on starches extracted from various vegetal sources such as corn (Kang et al, 1999;De Kerf et al, 2001;Adeil Pietranera & Narvaiz, 2001), wheat (MacArthur & D'Appolonia, 1984;Koksel et al, 1996), potato (Ezekiel et al, 2007;Shishonok et al, 2007), barley endosperms (Faust & Massey Jr., 1966), rice (Wu et al, 2002;Bao et al, 2005) or sago (Pimpa et al, 2007). The reported data showed that ionizing radiation treatment generates free radicals on starch molecules that can alter their size and structure (Raffi et al, 1980;Ciesla et al, 1991;Grant & D' Appolonia, 1991;Sabularse et al, 1991;Sokhey et.…”

EFFECT OF GAMMA IRRADIATION ON THE GROWTH AND DEVELOPMENT OF SAGO PALM (Metroxylon sagu Rottb.) CALLI

“…Two types of mutagens are chemical mutagens such as DMSO, EMS, MMS, dNS; and physical mutagens such as cosmic ray, ion beam, and irradiation using alpha, beta and gamma rays. Irradiation technique is more popular than chemical and other physical mutagenesis (IAEA 2012) because irradiation is rapid, convenient and more extensive and the ionizing energy penetrates rapidly through the polysaccharide granule (Bao et al 2005). The most popular irradiation is gamma ray irradiation from Co 60 which is widely used in agriculture (Piri et al 2011) as a mutagenesis agent for large commercial crops like ornamental plants (Barakat and El-Sammak 2011), food crops (IAEA 2012), pharmaceutical plants (Sung et al 2013) and oil palm (Rohani et al 2012).…”

Radiation Influence on Edible Materials

“…Gamma irradiation had no significant effect on the amylopectin branch chains, but produced more branch chains when the irradiation dosage was less than 9 kGy. It might be deduced that gamma irradiation caused the breakage of the amylopectin chains at the amorphous regions, but had little effects on the crystalline regions of starch granules, especially at low-dosage irradiation [30].…”