Influence of L-cysteine on the formation of bitter-tasting aminohexose reductones from glucose and L-proline: identification of a novel furo[2,3-b]thiazine.
Thermal treatment of a 1 + 1 mixture of glucose and L-proline led to the development of an intense bitter taste being reflected in high amounts of the bitter-tasting bispyrrolidino- (1) and pyrrolidinohexose reductones (2) formed. Heating the reaction mixture in the presence of L-cysteine drastically reduced the amounts of these aminohexose reductones and, thereby, the intensity of the bitter taste. Studies on the mechanism of the cysteine-induced reduction of the bitter taste revealed that the precursor of the aminohexose reductones, the hexose-derived acetylformoin (3), reacted more easily with L-cysteine to form the 7-hydroxy-4a,6-dimethyl-2H,3H,4aH-furo[2,3-b]thiazine (4), a previousely unknown Maillard reaction product, than with L-proline to the aminohexose reductones 1 and 2, thereby blocking the formation of bitter-tasting compounds.
Hofmann
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Deutsche Forschungsanstalt für Lebensmittelchemie, Lichtenbergstrasse 4, D-85748 Garching, Germany. thomas.hofmann@lrz.tum.de
D002851:Chromatography, High Pressure Liquid; D003545:Cysteine / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D015416:Maillard Reaction; D008956:Models, Chemical; D011392:Proline / Q000378:metabolism*; D013649:Taste; D013696:Temperature
D011392:Proline; D005947:Glucose; D003545:Cysteine