Formation of Aroma Compounds from Ribose and Cysteine during the Maillard Reaction

Abstract

The headspace volatiles produced from a phosphate-buffered solution (pH 5) of cysteine and a 1 + 1 mixture of ribose and [(13)C(5)]ribose, heated at 95 degrees C for 4 h, were examined by headspace SPME in combination with GC-MS. MS data indicated that fragmentation of ribose did not play a significant role in the formation of the sulfur aroma compounds 2-methyl-3-furanthiol, 2-furfurylthiol, and 3-mercapto-2-pentanone in which the carbon skeleton of ribose remained intact. The methylfuran moiety of 2-methyl-3-(methylthio)furan originated from ribose, whereas the methylthio carbon atoms came partly from ribose and partly from cysteine. In 3-mercapto-2-butanone one carbon unit was split from the ribose chain. On the other hand, all carbon atoms in 3-thiophenethiol stemmed from cysteine. In another trial cysteine, 4-hydroxy-5-methyl-3(2H)-furanone and [(13)C(5)]ribose were reacted under the same conditions. The resulting 2-methyl-3-furanthiol was mainly (13)C(5)-labeled, suggesting that it stems from ribose and that 4-hydroxy-5-methyl-3(2H)-furanone is unimportant as an intermediate. Whereas 2-mercapto-3-pentanone was found unlabeled and hence originated from 4-hydroxy-5-methyl-3(2H)-furanone, its isomer 3-mercapto-2-pentanone was formed from both 4-hydroxy-5-methyl-3(2H)-furanone and ribose. A new reaction pathway from ribose via its 1,4-dideoxyosone is proposed, which explains both the formation of 2-methyl-3-furanthiol without 4-hydroxy-5-methyl-3(2H)-furanone as an intermediate and a new way to form 3-mercapto-2-pentanone.

The role of sulfur chemistry in thermal generation of aroma

“…It is noteworthy that the hypothetical pathway in Figure 9.5 explains the formation of 17 without the necessary concomitant formation of its isomer, 2-mercapto-3-pentanone. Hence, this pathway agrees with the experimental absence of 2-mercapto-3-pentanone in the reaction of ribose with L-cysteine at 95 C, and pH 5 for 4 h (Cerny and Davidek, 2003). An alternative formation pathway to α-mercaptoketones passes through dicarbonyl compounds, which are known intermediates in the Maillard reaction.…”

“…Experiments with isotopically labelled ribose provided evidence that, under aqueous conditions and at pH 5, the carbon skeleton of ribose remains intact in 2-methyl-3-furanthiol, 2-furanmethanethiol and 3-mercapto-2-pentanone, which are key odourants (Cerny and Davidek, 2003). In 3-mercapto-2-butanone, either the C1 or C5 moiety is split off from ribose (Cerny and Davidek, 2004).…”

Basic Chemistry and Process Conditions for Reaction Flavours with Particular Focus on Maillard‐Type Reactions

“…Cerny and Davidek (2003) investigated the efficiency of this precursor system in the generation of the meat-like odourants 2-methyl-3-furanthiol (MFT) and 3-mercapto-2-pentanone (MP) relative to their formation from ribose/cysteine. Reacting 13 C 5 -labelled ribose together with unlabelled norfuraneol and cysteine under aqueous conditions (pH 5, 95 • C for 4 hours), the authors showed that mainly 13 C 5 -labelled MFT was formed, suggesting that norfuraneol is less important as intermediate of MFT.…”

“…Fig. 3.4 Proposed formation pathway for 3-mercapto-2-pentanone and 2-methyl-3-furanthiol from ribose and cysteine via the 1,4-dideoxyosone route (adapted from Cerny and Davidek, 2003).…”

Volatile compounds in meat and meat products

“…glucose forms pyrazines with lysine (Ames et al, 2001), and ribose forms many key sulfur compounds with cysteine, like e.g. : 2-furanmethanethiol, 3-mercapto-2-pentanone, 2-methyl-3-furanthiol, 3-mercapto-2-butanone, bis(2-methyl-3-furyl) disulfide, 2-acetyl-2-thiazoline, 1-mercapto-2-propanone and 3-methyl-3-thiophenethiol (Hofmann & Schieberle, 1995;Cerny & Davidek, 2003).…”