The Scientific Identification of Oleogustus
For centuries, the sensation of eating fat was largely attributed to its texture—the smooth, rich mouthfeel of cream, butter, or oil. While this tactile sensation is undoubtedly a significant part of the eating experience, scientists have long theorized that there might be a more fundamental taste component at play. In 2015, research from Purdue University provided groundbreaking evidence that confirmed the existence of a sixth basic taste specifically for fat, naming it oleogustus. The word itself is a combination of the Latin words 'oleo' for oily and 'gustus' for taste.
Unlike the pleasant tastes of sweet or umami, oleogustus is often described as slightly bitter or sour, and generally becomes more unpleasant as the concentration of fatty acids increases. This is particularly noticeable in rancid or spoiled fats, where the taste of oxidized fatty acids is a distinct deterrent. This aversion to high concentrations of fat taste is thought to be an evolutionary mechanism to protect us from consuming spoiled food, similar to how bitterness warns us of potential toxins.
How We Detect Fat Taste
The key to understanding oleogustus lies not in the triglycerides that make up most of the fat we eat, but in the non-esterified fatty acids (NEFAs) that are released during digestion. When these fatty acids are cleaved from their triglyceride molecules, they can be detected by receptors on the tongue. This is a crucial distinction, as the texture of fat is a separate sensation from its actual taste.
Scientists have identified specific protein receptors, such as CD36, on the taste buds that appear to play a role in detecting fatty acids. Variations in this gene may influence an individual's sensitivity to fat taste, which could have implications for dietary preferences and obesity research. Further studies have shown that different chain lengths of fatty acids can elicit slightly different taste perceptions.
Oleogustus vs. Other Taste Sensations
To fully appreciate oleogustus, it is helpful to compare and contrast it with the other known taste modalities. While the five other basic tastes—sweet, sour, salty, bitter, and umami—are all distinct, oleogustus occupies its own unique perceptual space. The following table clarifies the differences.
| Taste Sensation | Stimulus | Associated Flavor Profile | Biological Significance |
|---|---|---|---|
| Sweet | Sugars (carbohydrates) | Pleasant, sugary, sweet | Signals high-energy food source |
| Sour | Acids | Tart, acidic | Signals unripe or spoiled food |
| Salty | Sodium chloride | Salty, savory | Signals essential electrolytes |
| Bitter | Alkaloids, toxins | Unpleasant, pungent | Signals potential poisons |
| Umami | Glutamate, nucleotides | Savory, meaty, "delicious" | Signals protein-rich food source |
| Oleogustus | Free fatty acids | Oily, waxy, potentially unpleasant | Signals presence of fat, high energy |
The Lingering Sensation of Kokumi
It is important not to confuse oleogustus with another Japanese flavor concept known as kokumi. While both are complex sensations, they function differently. Kokumi, which translates to "rich taste," is not a taste in itself but rather a flavor modifier that enhances and deepens other tastes. It provides a sense of mouthfeel, continuity, and richness that amplifies the basic five tastes. Unlike oleogustus, which is the direct taste of fat, kokumi is more about the overall flavor experience.
Foods with kokumi-enhancing properties include aged cheese, garlic, and yeast extracts, and they achieve their effect by activating calcium receptors on the tongue. While oleogustus is a specific taste sensation, kokumi is the rich, lingering effect that can make a food more satisfying and full-bodied.
The Impact on Food and Nutrition
The discovery of oleogustus has significant implications for both the food industry and nutritional science. For food developers, understanding the specific taste of fat allows for the creation of better-tasting low-fat products by compensating for the missing oleogustus sensation. It also provides a new avenue for exploring how flavors interact and how fat contributes to the overall appeal of a food.
From a nutritional perspective, recognizing oleogustus helps us better understand our relationship with food. It is clear that the body is biologically equipped to detect fat through a specific taste pathway, separate from its caloric content or texture. This could lead to a better understanding of how the body regulates fat intake and how dietary choices are influenced by taste perception.
Furthermore, research suggests that the amount of the CD36 receptor, which detects fat, can be influenced by diet. A high-fat diet may lead to a lower production of this receptor, potentially making an individual less sensitive to the presence of fat in food. This provides a compelling link between dietary habits and the biology of taste perception. For a deeper dive into the specific research on this topic, the paper "Oleogustus: The Unique Taste of Fat" provides valuable insight into the perceptual mapping of fatty acids.
Conclusion
The question "What is the taste of fat called?" is now definitively answered by the term oleogustus. This sixth basic taste is distinct from the mouthfeel of fat and the flavor-enhancing properties of kokumi, representing the unique taste of non-esterified fatty acids. While often perceived as unpleasant at high concentrations, its presence is a vital biological signal related to energy and food quality. The scientific validation of oleogustus opens new doors for nutritional research and food development, providing a richer understanding of how we experience one of the most important components of our diet.
