Formation of Pyrazines in Maillard Model Systems of Lysine-Containing Dipeptides

Abstract

Whereas most studies concerning the Maillard reaction have focused on free amino acids, little information is available on the impact of peptides and proteins on this important reaction in food chemistry. Therefore, the formation of flavor compounds from the model reactions of glucose, methylglyoxal, or glyoxal with eight dipeptides with lysine at the N-terminus was studied in comparison with the corresponding free amino acids by means of stir bar sorptive extraction (SBSE) followed by GC-MS analysis. The reaction mixtures of the dipeptides containing glucose, methylglyoxal, and glyoxal produced 27, 18, and 2 different pyrazines, respectively. Generally, the pyrazines were produced more in the case of dipeptides as compared to free amino acids. For reactions with glucose and methylglyoxal, this difference was mainly caused by the large amounts of 2,5(6)-dimethylpyrazine and trimethylpyrazine produced from the reactions with dipeptides. For reactions with glyoxal, the difference in pyrazine production was rather small and mostly unsubstituted pyrazine was formed. A reaction mechanism for pyrazine formation from dipeptides was proposed and evaluated. This study clearly illustrates the capability of peptides to produce flavor compounds that can differ from those obtained from the corresponding reactions with free amino acids.

Evidence for pyrazine-based chromophores in cloudwater mimics containing methylglyoxal and ammonium sulfate

“…Reaction products of the methylglyoxal/AS system listed in Table 2 are very typical Maillard reaction products, observed in both cloud water simulations Lin et al, 2015;Sareen et al, 2010;Hawkins et al, 2016) and the chemical characterization of baked bread, cooked meat, aged cheese and other reactions between carbonyl containing compounds and 30 amines or amino acids (Koehler and Odell, 1970;Adams et al, 2008;Van Lancker et al, 2010;Divine et al, 2012). It is therefore surprising that pyrazine-based products, which are also well-known to form in Maillard reactions in food, have not been identified in the context of atmospheric reactions.…”

“…This mechanism is described as "the most accepted formation mechanism for pyrazine" in Maillard reactions in food (Adams et al, 2008;Van Lancker et al, 2010) Divine et al (2012) showed that among the four possible mechanisms of alkylpyrazine formation in aged Parmesan cheese, only the methylglyoxal-based mechanism correctly explains the observed products. Third, 2,5-DMP in particular has been shown to form in focused studies of Maillard reactions in food, specifically in cases where methylglyoxal was exposed to amine-containing compounds (Adams et al, 2008;Van Lancker et al, 2010;Divine et al, 2012;Yu et al, 2017). In Van Lancker et al (2010), the reaction of methylglyoxal with heated free amino acids and lysine containing dipeptides 25 produced 2,5(6)-DMP and trimethylpyrazine at 10-100 fold times the signal of other pyrazines.…”

“…Table 3 provides a complete list of proposed PBC, none of which have been previously reported with structural assignments in atmospheric chemistry studies. A number of these structures have been reported, however, in the chemistry of Maillard reactions in food and food models (Adams et al, 2008;Van Lancker et al, 2010;Yu et al, 2017;Divine et al, 2012).…”

“…Third, 2,5-DMP in particular has been shown to form in focused studies of Maillard reactions in food, specifically in cases where methylglyoxal was exposed to amine-containing compounds (Adams et al, 2008;Van Lancker et al, 2010;Divine et al, 2012;Yu et al, 2017). In Van Lancker et al (2010), the reaction of methylglyoxal with heated free amino acids and lysine containing dipeptides 25 produced 2,5(6)-DMP and trimethylpyrazine at 10-100 fold times the signal of other pyrazines. Its presence in relatively large quantities suggests that the energetics of the 2,5-DMP pathway are favorable.…”

Identification of volatile compounds in Antarctic krill (Euphausia superba) using headspace solid-phase microextraction and GC-MS

“…[20,21] Pyrazines commonly provide a roasted flavor and a nutty and toasted odor. [22,23] Some studies have reported that pyrazines smell like roasted potato, [23] and have been studied principally in virtue of their characteristic flavor notes in various foods. [19] Esters such as hexyl acetate, present in seafood products, are associated with fruity sensory notes.…”