Abstract
Using electron spin resonance (ESR) spectroscopy, we revealed heating effects on irradiated pepper. The representative ESR spectrum of the irradiated pepper is consisted of four components a sextet centered at g=2.0, a singlet at the same g-value, a singlet at g=4.0 and side peaks near g=2.0. The first one is attributable to a signal with hyperfine (hf) interactions of Mn2+ (hf constant=7.4 mT) . The second one is due to an organic free radical that is induced by the γ-ray irradiation. The third one may originated from Fe3+ in the nonhem proteins. The fourth signal was found at the symmetric positions of the organic free radical, i.e, the second signal. Upon heating, the forth signals decreased monotonicaly. The ESR signal of the pepper heated for more than 10min was essentially the same as that before the irradiation. On the other hand, the second signal increased and then leveled off at a constant value by further heating. This is indicative the occurrence of some biochemical reactions such as Maillard reaction during heating procedures.
