Fat appetite in rats: flavor preferences conditioned by nutritive and non-nutritive oil emulsions.

Two experiments examined the rat's preference for flavors associated with nutritive corn oil and non-nutritive mineral oil emulsions. In Experiment 1 food deprived rats developed a preference for a flavor mixed into a 7.1% corn oil emulsion over a flavor presented in water. A significant but weaker preference was obtained for a flavor mixed into a 7.1% mineral oil emulsion. In Experiment 2 the rats acquired a preference for a flavor that preceded the ingestion of the corn oil emulsion by 10 min. The mineral oil emulsion, however, failed to condition a flavor preference using this delay paradigm. The results suggest that both the orosensory properties (flavor) and postingestive nutritive effects of oil can reinforce flavor preferences. The appetite for dietary fats is, therefore, a combined response to the flavor and nutritive qualities of this class of nutrients.