Browning mechanisms of mei liqueur were studied using model solutions containing 28% ethanol in 0.1 M citrate solution (pH 3.0). Catechin alone was stable in the model solution but degraded rapidly to form hydroxymethyl furfural (HMF) in incubation with fructose at 70 °C. The rate of increase in the absorbance at 420 nm also suggested that fructose was more potent than glucose in enhancing browning in acidic ethanolic environment. We propose that the major browning mechanisms in mei liqueur are the oxidation and condensation of tannins and the interactions between tannins and HMF derived from fructose, rather than Maillard reaction, ascorbic acid degradation, or caramelization.
