Birnessite catalysis of the Maillard reaction: Its significance in naturalhumification

dAlthough mineral colloids are known to play a significant role in transfor ming organic matter in soils and sediments, there still are many gaps in ou r understanding of the mechanisms of organic-mineral interactions. In this study, we investigated the role of a major oxide-mineral bimessite (a form of Mn(IV) oxide) in catalyzing the condensation reaction between sugars and amino acids, the Maillard reaction, for forming humic substances. The Mail lard reaction is perceived to be a moor pathway in natural humification, Us ing a suite of spectroscopic methods (including F-SR, XANES, EXAFS and C-13 NMR), our results show that Mn(IV) oxide markedly accelerates the Maillard reaction between glucose and glycine at ranges of temperatures and pH typi cal of natural environments. These results demonstrate the importance, of m anganese oxide catalysis in the Maillard reaction, and its significance in the natural abiotic formation of humic substances.