EPR identification of irradiated Monascus purpureus red pigment

Fresh red alimentary pigment extracted from Monascus purpureus fungus exhib its an intense EPR line consisting of a single, narrow line, attributed to a quinone radical. When irradiated with 7 MeV electrons or Co-60 gamma-rays , the amplitude of this line increased with the absorbed dose following a s aturation exponential dependency up to 10 kGy. During annealing treatment ( isothermal heating at 100 degrees C) the irradiation centers decay exponent ially with a half-life time of 2.30 min. (C) 1999 Elsevier Science Ltd. All rights reserved.