Enhancement of the perceived sucrose sweetness in the rat by thaumatin

After conditioned aversion to a 0.18 mol/l sucrose solution rats do not reject a solution of 0.03 mol sucrose per l (near threshold) or a solution of thaumatin (0.2 g/l), which elicits no response in the rats' taste nerves. However, a mixture of the latter two solutions is rejected just as the 0.18 mol/l sucrose solution. This means that for the rat the mixture has a sucrose-like taste. So, thaumatin enhances sucrose-like sweetness in this animal. Electrophysiological measurements in the chorda tympani indeed show an enhancement of the sucrose response of almost 20 percent by the addition of thaumatin (0.2 g/l) to a sucrose solution of 0.5 mol/l.