Kinetic Study of the Maillard Reaction in Thin Film Generated by Microdroplets Deposition

Abstract

The Maillard reaction kinetics in the confined volume of the thin film produced by ESI microdroplet deposition was studied by mass spectrometry. The almost exclusive formation of the Amadori product from the reaction of D-xylose and D-glucose toward L-glycine and L-lysine was demonstrated. The thin film Maillard reaction occurred at a mild synthetic condition under which the same process in solution was not observed. The comparison of the thin film kinetics with that of the reaction performed in solution showed strong thin film rate acceleration factors.

Sulfuric Acid Catalyzed Esterification of Amino Acids in Thin Film

“…In the last few years, several milestone reactions of organic chemistry have been studied in the microdroplets generated into the electrospray ionization (ESI) source of a mass spectrometer. − It has been demonstrated that in the confined volume of the charged microdroplets the reaction rates are accelerated up to 10 5 times compared with the same process in bulk. Moreover, the microdroplets landing onto a solid surface generate a thin film by which the neutral products of the reaction can be separated and quantified. − The thin film retains the peculiar confined volume of the microdroplets needed for reaction acceleration, but it is characterized by a longer lifetime that allows one to extend the reaction time to any desired value. Low molecule solvation, formation of highly reactive transient ionic species, extreme pH value, and a high interfacial electric field are some of the parameters invoked to explain the strong acceleration factors observed in confined volumes with respect to the same processes in bulk. − From this point of view, the carboxylic acid esterification reaction, similarly to other dehydration reactions, − may benefit from the peculiar fast solvent evaporation operative in the microdroplet/thin film system.…”