An EPR study into the effect of annealing on both the Mn2+ and free radical signal in lentil

The results of an EPR investigation on dry lentil (macrosperma) are reporte d in the present work. The EPR spectrum of lentil is composed of an equally spaced sextet and a single weak resonance line appearing at g=2.0050. Whol e intact individual and decorticated seeds and testa were studied separatel y; however, ground lentil was used throughout the work to avoid any possibl e problems arising from the microwave cavity filling factor. Although intac t and decorticated seeds were found to exhibit both Mn2+ and radical signal s, the testa exhibited only the radical signal. An increase and decrease of Mn2+ and radical signals were observed, respectively, below room temperatu re. Above room temperature, they both decreased and these decreases were ir reversible. The kinetics of these decreases were studied in detail over a t emperature range of room-423 K by annealing samples at different temperatur es for various times.