Abstract:

The effects of reaction conditions including pH, temperature and time on the formation of α-dicarbonyl
compounds (α-DCCs) from ribose/L-cysteine Maillard reaction model system were examined by separation and identification
of α-DCCs by HPLC and LC-ESI-MS-MS after trapped with o-phenylenediamine (OPD). The results showed that the
α-DCCs identified in the model were 1,2-pentosone, 2,3-pentosone, 3-deoxypentosone (3-DP), 1-deoxypentosone (1-DP),
N-1,4,5-trideoxy-2,3-dioxopentyl-L-cysteine, 1,4-dideoxypentosone (1,4-DDP), glyoxal (GO) and methylglyoxal (MGO).
Among them the dominant were 1,2-pentosone, 1,4-DDP, 1-DP and N-1,4,5-trideoxy-2,3-dioxopentyl-L-cysteines. At pH
3.6, N-1,4,5-trideoxy-2,3-dioxopentyl-L-cysteine and GO; at pH 4.6–6.6, 1,2-pentosone, 3-DP and 1,4-DDP; and at pH 7.6,
2,3-pentosone, 1-DP and MGO were readily formed. Based on these results, a pathway of α-DCC formation at different
pH was proposed. The concentration of α-DCC at 115 ℃ was higher and then was decreased when heated at a higher
temperature (125 ℃) after long reaction time (60 min). The temperature and pH were the most important factors that affect
the formation of α-DCCs.

Key words: ribose；L-cysteine；Maillard reaction；&alpha, -dicarbonyl compounds