Effect of glycine on reaction of cysteine-xylose: Insights on initial Maillard stage intermediates to develop meat flavor

- LC-MS was used to determine initial intermediates in complex Maillard reaction.
- Glycine reacts with xylose against cysteine affects profile of initial intermediates.
- Addition of glycine in cysteine-xylose can accelerate the browning reaction.
- Effect of glycine on meat flavor formation differs from that on browning reaction.
- Ratios of cysteine to glycine should be controlled to maximise yielding meaty flavors.

The meat-like reactions of l-cysteine and d-(+)-xylose with or without glycine were investigated. LC-MS was used to quantitatively determine the initial stage intermediates including 2-threityl-thiazolidine-4-carboxylic acid, Cys-Amadori, and Gly-Amadori in the reaction mixtures. The results showed that the addition of glycine was only in positive correlation with the browning feature of cyseine-xylose reaction. When excessive glycine was added, a high browning rate would be achieved, but it did not benefit the formation of meaty compounds. For a complex meat-like reaction system containing cysteine, reducing sugars and glycine, to overcome the low rate of reaction, and particularly, to minimize the inhibitive effect of cysteine in the generation of meaty flavors, selection of an appropriate ratio between cysteine and glycine is important in an effort to make amounts of the intermediates of Cys-Amadori and Gly-Amadori approximately equally consist in the reaction mixture.

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