For years, scientists thought human taste receptors could detect only four basic tastes in food: sour, sweet, salty and bitter. Since 2002 scientists have recognized a fifth taste: umami (savory). Now they may be ready to add a sixth: fat (or oleogustus, as the author of a 2015 study wants to call it).
Russell Keast, a researcher in sensory science at Deakin University in Australia, said in an email, "We believe that if you are sensitive to fat taste in the oral cavity, your gut is also sensitive to fat. This has implications on consumption, as fat is a good fullness-inducing nutrient, as long as your body can recognize it. Those who are less sensitive to fat taste have trouble as their body fails to recognize dietary fat and in turn they don’t feel as full, and consume more."
Keast went on to say that the food industry can use this knowledge by delivering fatty acids to the gut to create a feeling of fullness, not by adding more fat, but by adding fatty acids.
A 2012 study first identified a human receptor that can taste fat and suggested that some people are more sensitive to the presence of fat in foods due to a variation in the CD36 gene. Other studies have also generally found that some people are more, while others are less, sensitive to fatty acids (the components that make up fat) in food.
The fat-sensitive people tend to better detect the fat content of food, eat less total dietary fat, and sometimes have a lower BMI than people who are less sensitive to fatty acids. Other findings suggest that a high-fat diet may decrease fat sensitivity in lean individuals and that a fat-restricted diet may decrease the pleasantness, taste and preference for high-fat foods.
Richard Mattes, a professor of nutrition science at Purdue University, agrees with Keast, saying in an email that food manufacturers could use very low concentrations of fatty acids to reproduce the flavor-enhancing taste of fat. These small amounts would be nutritionally inconsequential, meaning they wouldn't add fat content to food. The current standard industry practice is to mimic the taste of fat by replicating the texture of how fats feel in the mouth. Mattes noted that a new understanding of fat as a taste could be especially important in designing fat replacers.
But all this talk of adding fatty acids to foods to imitate the taste of fat may be a bit early, according to Dr. Caroline Withers, Senior Sensory and Consumer Scientist at MMR Research Worldwide. Withers says understanding of fatty taste is still in the early stages and not ready for direct application in food R&D. One challenge she notes is that different fatty acids have different tastes, and experts still need to understand how the varying tastes affect foods.