Do non-thermal effects exist in microwave heating of glucose aqueous solutions? Evidence from molecular dynamics simulations.

The existence of microwave non-thermal effects in food processing is still debated. In this study, molecular dynamics (MD) simulations were performed to investigate the conformation, electrostatic profiles, and intramolecular hydrogen bonds (intra-HB) of glucose in aqueous solution under alternating electric fields of microwaves ranging from 0 to 10 V/m at 2.45 GHz. The results showed a field-induced threshold of 10 V/m. At the threshold, alternating microwaves reoriented the flexible moieties and thus enhanced the intra-HB. The conformational transition among gg, gt, and tg conformers at 10 V/m possibly resulted from the uneven electrostatic potential and the increased intra-HB. In practice, the maximum electric field of microwaves is several times weaker than the threshold, verifying the absence of microwave non-thermal effects for glucose molecules in food processing. This study provides a novel strategy to evaluate the potential non-thermal effects of microwaves in food processing and the related underlying food safety issues.