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Mechanism of formation of thermally generated potential toxicants in food-related model systems

McGill University
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  • Chemistry - General


The detailed mechanism of formation of selected Maillard-induced toxicants generated in model systems containing 13C- and 15N-labeled precursors, were investigated using isotope labeling and Py-GC/MS based techniques. Investigation of different sources of acrylamide (AA) formation in model systems have indicated the presence of two pathways of acrylamide generation; the main pathway specifically involves asparagine to directly produce acrylamide after a sugar-assisted decarboxylation step that passes through a 5-oxazolidinone intermediate and the second, non-specific pathway involves the initial formation of acrylic acid from different sources and its subsequent interaction with ammonia and/or amines to produce acrylamide or its N-alkylated derivatives. Furthermore, to identify the relative importance of AA precursors, the decarboxylated Amadori product (AP ARP) and the corresponding Schiff base were synthesized and their relative abilities to generate AA under dry and wet heating conditions were studied. Under both conditions, the Schiff base had the highest intrinsic ability to be converted into AA. To gain further insight into the decarboxylation step, the amino acid/sugar reactions were also analyzed by FTIR to monitor the formation of the 5-oxazolidinone intermediate known to exhibit a peak in the range of 1770-1810 cm-1. Spectroscopic studies clearly indicated the formation of an intense peak in the indicated range. Similar to acrylamide, mechanism of furan formation was also studied using 13C-labeled sugars and amino acids. These studies have indicated that furan can be formed through aldol condensation of acetaldehyde and glycolaldehyde and these precursors can be formed from certain amino acids, monosaccharides and ascorbic acid. Moreover, using specifically 13C-labeled sucrose at C-1 of the fructose moiety, hydroxymethylfurfural (HMF) formation was studied at different temperatures. Under dry pyrolytic conditions and at temperatures above 250oC, 90% o

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