abstract
Many reports claim the existence of athermal effects in microwave-induced reactions, and this challenge
the assumption that the thermal effect (heating) is the sole factor in microwave heating. Therefore,
microwave-induced Maillard reaction of d-glucose/glycine and degradation of polysaccharide from Porphyra
yezoensis (PSPY) were investigated. Browning reactions were monitored by measuring heating
rate, UV-absorbance and brown color, UV–vis and synchronous fluorescence spectra, GC/MS analysis and
intrinsic viscosity of degradation. Heating of d-glucose/glycine solution produced brown compounds
which were detected at A420, and the intermediate products, 2-acetylfuran and 5-methylfurfural, whose
fluorescence intensity evidenced their formation. Maximum emission of synchronous fluorescence spectra
of samples were at 430–440 nm and 370–390 nm. Both microwave and water bath heating did not
cause any compositional changes in the Maillard reaction products. All data failed to show any significant
athermal effects of compositional changes in the Maillard reaction products. It can be inferred that some
of the reports suggesting the existence of athermal effects, which could ascribe to the different set-up
obtained in not well temperature controlled microwave heating systems.
© 2013 The Authors. Published by Elsevier Ltd. All rights reserved.