Effect of high proton beam irradiation on pasting properties of rice starch
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J. Crop Sci. Biotech. 2013 (June) 16 (2) : 161~166 DOI No. 10.1007/s12892-013-0039-0 RESEARCH ARTICLE
Effect of High Proton Beam Irradiation on Pasting Properties of Rice Starch Sang Kuk Kim1, Hak Yoon Kim2,* Division of Crop Sciences, Gyeongsangbuk-do Agricultural Research & Extension Services, Daegu 702-708, Republic of Korea Department of Global Environment, Keimyung University, Daegu, 704-701, Republic of Korea
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Received: March 18, 2013 / Revised: April 14, 2013 / Accepted: May 18, 2013 Ⓒ Korean Society of Crop Science and Springer 2013
Abstract Rice seed was treated by high proton beam irradiation up to 1,200 Gy in order to elucidate physicochemical properties of irradiated rice starch. The decrease of amylose content in two rice cultivars ranged 3.5 to 3.6% compared to the non-irradiated rice under the highest proton beam irradiation (1,200 Gy). Gel consistency in japonica rice cultivar Ilpum was significantly increased with increasing proton beam irradiation. Its values approached 9.7 in the Ilpum rice cultivar and 8.7 cm in the Hanmaum rice cultivar. The peak viscosity, hot peak viscosity, cool peak viscosity, and setback were significantly decreased with increasing proton beam dose. High proton beam irradiation caused a significant decrease in the onset temperature (To), peak temperature (Tp), conclusion temperature (Tc), and enthalpy change (∆H). Gelatinization range (R) in two rice cultivars was more broaden in higher proton beam irradiation than in low proton beam irradiation. The crystallinity degree of two rice starches irradiated with high proton beam was significantly increased and it ranged from 3.25 and 4.39% compared to the non-irradiated rice starches. It might be deduced that proton beam irradiation causes changes of starch, especially at high irradiation of proton beam. Key words: Oryza sativa L., proton beam, rice, starch viscosity
Introduction Rice is the most important cereal crop and the staple food of over half the world's population. As the primary dietary source of carbohydrate in these populations, rice plays an important role in meeting energy requirements and nutrient intake (Hu et al. 2004). Recent studies demonstrated that differences in physical behavior and functionality of rice starch are related to starch structure (Vandeputte et al. 2003; Nakamura et al. 2002). The different starch structures originate from the varying activity levels of the isoforms of starch biosynthetic enzymes (Vandeputte and Delcour 2004). The physical modification methods of starch can be accomplished by gamma irradiation, microwave (Lewandowicz et al. 2000), ultraviolet (Bertolini et al. 2001; Fiedorowicz et al. 1999), ultrahigh hydrostatic pressure (Katopo et al. 2002), and hydrothermal treatment (Jacobs and Delcour1998). As a useful method for producing modified Hak Yoon Kim ( ) E-mail: [email protected] Tel: +82-53-580-5918/Fax: 82-53-580-0294 The Korean Society of Crop Science
starch, gamma irradiation generates free radicals on the starch molecules that alter molecular size and structures (S
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