The reaction of the N
6-amino group
of lysine residues and 1,2-dicarbonyl compounds during Maillard processes
leads to advanced glycation end products (AGEs). In the present work,
we deliver a comprehensive analysis of changes of carbohydrates, dicarbonyl
structures, and 11 AGEs during the grilling of porcine meat patties.
While raw meat contained mainly glyoxal-derived N
6-carboxymethyl lysine (CML), grilling led to an increase
of predominantly methylglyoxal-derived AGEs N
6-carboxyethyl lysine (CEL), N
6-lactoyl lysine, methylglyoxal lysine dimer (MOLD), and methylglyoxal
lysine amide (MOLA). Additionally, we identified and quantitated a
novel methylglyoxal-derived amidine compound N
1,N
2-di-(5-amino-5-carboxypentyl)-2-lactoylamidine
(methylglyoxal lysine amide, MGLA) in heated meat. Analysis of carbohydrates
suggested that approximately 50% of the methylglyoxal stemmed from
the fragmentation of triosephosphates during the heat treatment. Surprisingly, N
6-lactoyl lysine was the major AGE, and based
on model incubations, we propose that approximately 90% must be explained
by the nonenzymatic acylation of lysine through S-lactoylglutathione, which was quantitated for the first time in
meat herein.