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Free radicals in irradiated wheat flour detected by electron spin resonance

机译：电子自旋共振检测辐照小麦面粉中的自由基

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By electron spin resonance (ESR) spectroscopy, we revealed free radicals in wheat flour before and after gamma-ray irradiation and their thermal behavior during heat treatment. The ESR spectrum of wheat flour before irradiation consists of a sextet centered at g = 2.0 and a singlet signal at the same g-value position. The first one is attributable to a signal with hyperfine (hf) interactions of Mn2+ ion (hf constant, 7.4 mT). The second signal originates front the carbon-centered radical. Upon gamma-ray irradiation, however, a new signal with two triplet lines at the low- and high-Field ends was detected on the Mn2+ sextet lines. We analyzed the triplet ESR lines as due to powder spectra (rhombic g-tensor symmetry) with nitrogen (N-14) hf interactions. This indicates that a new organic radical was induced in the conjugated protein portion of wheat flour by gamma-ray irradiation. The intensity of the organic free radical at g = 2.0 detected in irradiated wheat flour increased monotonically under thermal treatment. The analysis of the time-dependent evolution process on the basis of the theory of transient phenomena as well as the nonlinear least-squares numerical method provided a unique time constant for the radical evolution in wheat flour during thermal treatment.
机译：通过电子自旋共振（ESR）光谱，我们发现了小麦粉中的γ射线辐射前后的自由基及其在热处理过程中的热行为。辐照前小麦面粉的ESR光谱由以g = 2.0为中心的六重音和在相同g值位置的单重态信号组成。第一个可归因于信号与Mn2 +离子的超精细（hf）相互作用（hf常数，7.4 mT）。第二个信号起源于碳中心自由基。然而，在伽马射线辐照下，在Mn2 +六重奏线上检测到在低场和高场端带有两条三重态线的新信号。我们分析了三重态ESR谱线，归因于与氮（N-14）hf相互作用的粉末光谱（菱形g张量对称）。这表明通过γ射线辐射在小麦粉的结合蛋白部分中诱导了新的有机自由基。在热处理下，经辐照的小麦粉中检测到的g = 2.0时有机自由基的强度单调增加。基于瞬态现象理论和非线性最小二乘数值方法对时间相关的演化过程进行分析，为小麦粉在热处理过程中的自由基演化提供了独特的时间常数。

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