Elucidation of nonthermal effects of microwave irradiation on the unfolding pathways of [beta]-lactoglobulin and hemoglobin

In recent years there has been considerable interest in the development of microwave-based food processing technologies. Microwave radiation is considered to have both thermal and non-thermal effects. The thermal effects are related to the heat generated by the absorption of microwave energy by water or by organic molecules, but very little is known about the mechanisms involved in the putative non-thermal effects. It has been postulated that the latter could involve a direct energy transfer from the electromagnetic field to the vibrational modes of macromolecules, altering their conformation. In the present study, the non-thermal effects induced upon irradiation of protein solutions with microwave energy were investigated by employing Fourier transform infrared spectroscopy, circular dichroism, and fluorescence spectroscopy to elucidate the unfolding pathways of hemoglobin and beta-lactoglobulin (5% in D2O) subjected to either microwave irradiation (2450 MHz) or conventional heating. (Abstract shortened by UMI.