Amadori Compounds as Nonvolatile Flavor Precursors in Processed Foods

Amadori compounds, derived from the condensation of amino acids with reducing sugars in the Mainard reaction, have been isolated from browned, dehydrated fruits and vegetables, bakery products, cane and beet molasses. and cured tobacco. The nonvolatile compounds' in their enolic forms are precursors of flavor compounds, particularly those with burnt and caramel-like aromas. A model basic Amadori compound, I-deoxY-l-piperidino-Dfructose, was pyrolyzed and the volatile products were isolated. These products, high boiling liquids and sublimable solids, consisted mainly of 4-carbon methyl reductones, a-piperidino-')'-butyrolactone, and piperidine amides of carbonic, formic, acetic, butyric, glycolic, and lactic acids. Only a trace of N-lactylpiperidine was found, indicating a predominance of 4:2 over 3:3 splitting of the hexose moiety. A reaction course through the 4-carbon reductones to the 2and I-carbon acid amides is suggested.