The orosensory recognition of long-chain fatty acids in rats.

To determine the selectivity of long-chain fatty acid (LCFA) in the oral cavity, short-term (5 min) two-bottle tests were conducted in rats. Fifteen male Wistar rats were given oleic acid, linoleic acid, linolenic acid, and their derivatives. All compounds used were 99% pure. The concentration of test fluids was made 1% in 0.3% xanthan gum to minimize postingestive and textural effects. The rats preferred LCFA fluids to the control of 0.3% xanthan gum solution. The preference order of LCFA was linolenic acid > linoleic acid > oleic acid. Four LCFA derivatives (methyl oleate, oleyl alcohol, methyl linoleate, and linolyl alcohol), triolein, and capric acid were not preferred to LCFA, but LCFA derivatives were preferred to the control of xanthan gum solution. These studies suggest that rats select LCFA from olfactory or gustatory cues that are related to both the carbon chain and carboxylate group.