Isolation and quantification in food of 6-(2-formyl-5-methylpyrrol-1-yl)-l-norleucine (“rhamnolysine”) and its precursor 3,6-dideoxy-l-mannosone

Maillard Reaction Products in Different Types of Brewing Malt

“…Therefore, an HPLC-MS/MS method was developed using a biphenyl-modified column, and quantitation was performed by standard addition as previously. 18 It is well established that 3-DG is the most abundant dicarbonyl structure in malt and beer, 6,9,12,13 which was corroborated in the present study (up to 9 mmol/kg, Table 5). As shown previously for Pilsner malts, 6 the molar ratio between 3-DG and N-ε-fructosyllysine was between 1.5 and 3.5 in light malts, whereas it ranged between 5 and 47 in dark malts, showing the disproportionately high formation of 3-DG in the advanced stage of the Maillard reaction.…”

“…[ 2 H 2 ]­CML was from PolyPeptide (Strasbourg, France). The following substances were synthesized according to literature methods: N -ε-fructosyllysine, N -ε-maltulosyllysine, N -ε-carboxymethyllysine, pyrraline, , formyline, methylglyoxal-derived hydroimidazolone 1 (MG-H1), maltosine, rhamnolysine, 5-(2′-formyl-5′-hydroxymethylpyrrol-1′-yl)-pentanal (pyrralinal), 5-(2′-formylpyrrol-1′-yl)-pentanal (formylinal), and the quinoxalines derived from l -3,6-dideoxymannosone, 3-deoxypentosone, 3-DG, 3-DGal, and from ( E )- and ( Z )-3,4-DGE …”

“…The fact that rhamnolysine can be quantitated in malt samples but not its precursor may substantiate the proposed formation of rhamnolysine from ARPs. 18,39 The concentrations of (Z)-3,4-DGE were astonishingly high (5−382 μmol/kg or 0.7−55 mg/kg), and in many of the dark and all roasted malts, it exceeded the concentration of 3-DGal. This may be due to the fact that formation of 3-DGal from 3,4-DGE requires the addition of water, which becomes limited at the high processing temperatures applied during production of the respective malts.…”

“…Similarly to a previously published method, a Kinetex 5-μm Biphenyl 100 Å column (100 × 2.1 mm, 5 μm) was used at room temperature. 18 The eluents (A, 0.075% acetic acid in water; B, a mixture of solvent A and methanol, 20/80, v/v) were applied at a flow rate of 0.3 mL/min in the gradient mode (0 min, 20% B; 5 min, 20% B; 10 min, 25% B; 15 min, 40% B; 20 min, 100% B; 22 min, 100% B; 24 min, 20% B; 32 min, 20% B). The parameters for MRM measurement of quinoxalines are listed in the Supporting Information (Table S3).…”

“…However, data on the occurrence of glycated amino acids in malt are scarce (Table ). , Beneath the formation of glycated amino acids, an important reaction in the final stage of the Maillard reaction in malt is Strecker degradation. Strecker aldehydes from malt are present in wort at the beginning of fermentation .…”