Siam Physics Congress 2018

Electron Spin Resonance Analysis of γ-induced Free Radicals in Riceberry Rice Grain

21 May 2018, 17:30

15m

์Nakorn Sawan Room

Oral Plasma and Ion Physics, Nuclear and Radiation Physics A4: Plasma and Nuclear Fusion

Speakers

Mr Panupong Rintarak (Department of Physics, Faculty of Science, Mahidol University) Busara Pattanasiri (Department of Physics, Faculty of Liberal Arts and Science, Kasetsart University Kamphaeng Saen Campus) S. AnupongMrs Sumalee Ninlaphruk (Office of Atoms for Peace) Somsak Dangtip (Mahidol University)

Description

Gamma irradiation has long been serving as one alternative preservation method for food and agriculture products. Initial physical interactions of gamma with biomaterials lead through radical formation, depolymerization, and molecular changes to eventual sterilization, decontamination and preservation. An effective penetration of gamma radiation homogenize the effects throughout the materials. Riceberry rice composes mainly of starch, which has $\alpha$-D glucopyranose (${\text{C}}_6{\text{H}}_{12}{\text{O}}_6$ or glucose) as a building block in its polysaccharide network. Follow irradiating rice with Co-60 gammas of a few kilograys, the polysaccharide chains have undergone several changes in their molecular structure, which lead to generation of free radicals. Electron spin resonance (ESR) analysis has shown that quite a few free radicals were formed with different strengths. Their respective Lande’s g-values were in the range of 1.9900 – 2.0180. Mechanisms such as hydrogen abstraction on C6 position, an internal hydrogen bonding between the C4 and C6 hydroxyl groups, or formation of primary hydroxyalkyl between C1 and C2 are presumably accounted for the formation of these free radicals.

Keywords: Gamma-ray irradiation, ESR, SEM, riceberry rice, depolymeriztion, crosslinking

Peer reviewing

Paper

Accepted on 8 Sept 2018 by spc2018 narasuan

SPC_2018_Paper_Panupong_Revised2.pdf