Free radicals in wheat seeds studied by electron spin resonance

We used electron spin resonance (ESR) to investigate free radicals in wheat seeds in air or under vacuum in relation, to I annealing temperature. Annealing in the 100 to 200 degreesC range resulted in concentration increases of free radicals in samples. A greater increase was observed for experiments carried out in air than for those under vacuum. Most free radicals occurred in the grain surface layer. The bran contained a concentration of free radicals 100 times greater than that of the white grain portion. The reaction of stable free radicals in bran was also studied during thermal decomposition of dibenzoyl peroxide at high pressure. They reacted with short-lived peroxyl radicals in bran to produce a nonradical product.