Free Radical Formation from Secondary Amines in the Maillard Reaction

Abstract

ESR spectroscopy has been used to study the formation of free radicals in the Maillard browning reaction, from the reaction between glycolaldehyde or glyceraldehyde and N,N‘-dialkylethylenediamines (alkyl = methyl, ethyl, iso-propyl, tert-butyl) in either aqueous buffer or in methanol. Two series of cyclic cation radicals are formed. The first is a 1:1 sugar:amine product in which the nitrogen atoms in 1 ethylenediamine molecule are bridged by a sugar molecule. The second, and more stable, is a 2:2 product in which a substituted dihydropyrazine cation radical is formed by the bridging of two amines with two sugars. In addition, nitroxide radicals are also observed when methanol is used as the solvent. A mechanism for the formation of these radicals in the early stages of the Maillard reaction is proposed. Keywords: Maillard reaction; cation radicals; ESR; dihydropyrazines

Effect of antioxidants on elimination and formation of acrylamide in model reaction systems

“…However, the results from our research suggested an increase in the total antioxidant capacity in Maillard reaction would increase acrylamide formation in another way. As antioxidants and free radicals are both formed in Maillard reaction [22,25,26], we suppose that free radicals eliminate the formed acrylamide and thus reduce the content of acrylamide of final Maillard reaction products (high-temperature processing foods). However, the antioxidants produced by Maillard reaction inhibit free radicals formation or hinder attack of acrylamide from the free radicals by extinction, which leads to a positive correlation between total antioxidant capacity (the oxidized antioxidants decreased total antioxidant capacity) and acrylamide formation.…”

Storage stability of cauliflower soup powder: The effect of lipid oxidation and protein degradation reactions

“…in the early stages of non-enzymatic browning reactions (Hayashi, Mase, & Namiki, 1985;Hoffman, Bors, & Stettmaier, 1999a;Namiki & Hayashi, 1975;Roberts & Lloyd, 1997), as well as in the Maillard reaction end-products, melanoidins (Hoffman, Bors, & Stettmaier, 1999b). Furthermore, Thomsen, Lauridsen, Skibsted, and Risbo (2005b) found a correlation between the formation of late-stage Maillard reaction products and change in the ESR line shape when studying milk powder.…”

Application of electron spin resonance (ESR) spectrometry in nutraceutical and food research

“…DMPO is a commonly used spin-trapping agent. It has been wide accepted that ESR is a powerful tool to identify the radical species, as well as to investigate the chemical mechanism involved in free radical-mediated reactions [27].…”

“…In 1997, Roberts and Lloyd [27] conducted an ESR investigation on free radical formation in the Maillard reaction, which might give more insights of the reaction and lead to a better understanding of the chemical mechanism(s) involved. Results showed that three series of free radicals were generated in the reaction between secondary amine and glycolaldehyde or glyceraldehyde.…”

“…Results showed that three series of free radicals were generated in the reaction between secondary amine and glycolaldehyde or glyceraldehyde. Furthermore, it was concluded that the species II radical was revealed to play the most important role in the Maillard reaction pathway [27].…”