Cereal Chem 48:351 - 355.  |  VIEW ARTICLE
Electron Spin Resonance Study of Stable Free Radicals in Wheat.

J. J. Windle and J. J. Evans. Copyright 1971 by the American Association of Cereal Chemists, Inc. 

Electron spin resonance (ESR) spectra have been obtained on single wheat kernels; on the bran, shorts, and flour from two varieties; and on gluten, starch, and water-solubles from flour. The wheat kernel exhibited two signals, one attributable to manganese and the other to a free radical. Each of the milling fractions also showed free radical spectra similar to the wheat kernel, with the signal from the bran and shorts being about ten to twenty times as intense as that from the break and reduction flours. When flour was separated into gluten, starch, and water-solubles, a different spectrum was obtained, with the largest free radical signal occurring in the gluten. Owing to lack of hyperfine structure, the identities of the free radicals could not be established. The ESR spectrum in the milling fractions showed manganese to be concentrated mainly in the bran and shorts fractions. Among the flour fractions, only the water-solubles gave a manganese spectrum that remained after dialysis. A comparison of the intensity of free radical and manganese signals in various milling fractions with their nitrogen, fiber, ash, and fat content indicated that these signals are concentrated in outer portions of the kernel.