Chemical reception of fats in the oral cavity and the mechanism of addiction to dietary fat.

Fatty foods, such as cream cakes, butter cookies and fried potatoes, give us some sort of satisfaction. When we eat fatty foods, we perceive them to be tender and juicy because the melted fat spreads throughout the oral cavity. It is thought that the oral sensation constitutes the palatability of fat. Today, various kinds of fat substitutes that have a similar texture to real fat have been developed, such as those used in soft-serve ice cream and low-calorie mayonnaise. Most of these substitutes are made from polysaccharides and reduce the calorie count without any marked change in taste. The tastes of fat substitutes, however, are not palatable in themselves. By retaining just a little real fat in food, the ‘body’ or ‘thickness’ of that food can be maintained. Therefore, the palatability of fat cannot be explained completely by its texture. On the other hand, some researchers maintain that odor is important in the palatability of fat. However, even anosmic rodents show a strong preference for fat (Takeda et al., 2001; Fukuwatari et al., 2003). In terms of the gustatory cues for fat, recent evidence suggests that dietary fat, especially free fatty acids, may be perceived chemically in taste-bud cells.