Oxidative Pyrolysis and Postpyrolytic Derivatization Techniques for the Total Analysis of Maillard Model Systems: Investigation of Control Parameters of Maillard Reaction Pathways

Abstract

Factors that regulate various pathways of Maillard reaction leading to aroma, color, or carcinogen generation have not been identified, due to the difficulties associated with analyzing complex reaction mixtures. In particular, the role played by oxidation in directing aromagenic, chromogenic, or carcinogenic pathways is not well understood. In order to overcome the analytical difficulties, novel Py-GC/MS-based methodologies were developed to analyze volatile and nonvolatile residues of Maillard reaction products generated from the same model system under air or helium atmosphere. The analysis of nonvolatiles was achieved through a postpyrolytic in situ derivatization technique using hexamethyldisilazane, and pyrolysis under air was achieved through modification of the GC equipped with sample concentration trap to allow gas stream switching and subsequent isolation of the pyrolysis chamber from the analytical stream. In this approach label incorporation from the starting materials can be observed in both volatile and nonoxidative conditions for mechanistic studies. In addition, monitoring of redox potentials, oxygen consumption, and color generation of relevant model systems over time were also carried out at different temperatures. The data collected have indicated that perturbation in the redox potential of Maillard model systems by external (oxidizing conditions) or internal (formation of reductones) factors can alter the balance among the four critically important groups of precursors: alpha-dicarbonyl, alpha-hydroxycarbonyl, 2-aminocarbonyls, and 2-(amino acid)-carbonyl compounds and hence control the relative importance of aromagenic versus chromogenic pathways.

Effects of surface Fe(III) oxides in a steel slag on the formation of humic-like dark-colored polymers by the polycondensation of humic precursors

“…These results indicate that the condensation of glycine with catechol and/or glucose was decreased in the HNO 3 and HF treated slag samples. In addition, the number average (M n ) and weight-average (M w ) molecular weights for polymers produced in the presence of the HNO 3 and HF treated slag were significantly lower than those for the untreated slag ( Table 2).…”

“…In HS formation, biomacromolecules such as proteins, polysaccharides, lignins and polyphenols are hydrolyzed to low-molecular-weight compounds such as amino acids, sugar and quinone, which are referred to as humic precursors. These precursors are subsequently recombined via polycondensation reactions to form humic-like dark-colored polymers [1][2][3]. It has been reported that minerals in soil can influence the formation of dark-colored polymers that are formed by the polycondensation of humic precursors.…”

Hydroxyl Radicals in E-Cigarette Vapor and E-Vapor Oxidative Potentials under Different Vaping Patterns

“…In addition, there is limited information available on the redox potentials of flavoring chemicals and their thermal degradation products at temperatures of 100−150 °C. 16,35,36,49 The redox potential and the thermal oxidation of the flavoring chemicals should be evaluated using comparable heating temperatures of e-cigarettes (i.e., 200−300 °C).…”

Approaches to Wine Aroma

“…Pathways leading to trimethylpyrazine from a precursor of tetramethylpyrazine, dihydrotetramethylpyrazine, 2 , are proposed in 1. Dihydropyrazines are very slow to oxidize in the presence of air, 8,9 leaving diacetyl as the oxidant 10 . Adduct 3 is formed between 2 and a molecule of diacetyl (a similar addition of a dihydropyrazine was shown 11 to add to formaldehyde).…”