Effects of supercritical carbon dioxide on volatile formation from Maillard reaction between ribose and cysteine

BACKGROUND: Supercritical carbon dioxide (SC-CO2) technology is being used in an increasing number of food-manufacturing applications; however, its effect on the Maillard reaction is not well studied. The objective of this study was to investigate the effect of SC-CO2 treatment (140 degrees C, 40 MPa) on the Maillard reaction of an aqueous ribose-cysteine model system under varying pH conditions (5.6, 7.0 and 8.0), with emphasis on the formation of volatile compounds. RESULTS: SC-CO2 had a suppressing effect on the browning stages of the reaction under acidic and neutral pH conditions, while it appeared to have an accelerating effect at pH 8.0. Over 70 volatile compounds were positively identified from the headspace of the model system by gas chromatography-mass spectrometry. The volatiles were dominated by sulfur-containing compounds including thiophenes and fused bicyclic sulfur-containing compounds under all experimental conditions. Several compounds, including 2-methyl-3-furanthiol, 2-furanmethanethiol, 3-thiophenethiol, and 2-methyl-3-thiophenethiol, and one of the intermediates, furfural, were generated in much higher amounts in the SC-CO2-treated samples, especially at alkaline and neutral pH values. CONCLUSION: SC-CO2 treatment was inhibitory to the formation of most volatiles in the Maillard reaction, but enhanced the formation of some intermediates and well-known meaty flavoured compounds. (c) 2007 Society of Chemical Industry.