Scientists Confirm That Fat Is the 6th Basic Taste
Now we totally understand our bacon obsession. While we hinted at this new basic taste earlier this year, researchers at Purdue University have now confirmed that along with salty, sweet, bitter, sour, and umami, the sixth basic taste is oleogustus, a.k.a. fat. Although it doesn’t roll of the tongue, oleogustus is comprised of fatty acids, which adds appeal to foods like butter.
Just to confirm, scientists are not calling oleogustus a “taste bud.” Science long ago scrapped the taste bud map, and the idea that the tongue dedicates certain regions to different taste receptors is now considered a scientific myth.
"Most of the fat we eat is in the form of triglycerides, which are molecules comprised of three fatty acids," said Richard D. Mattes, professor of nutrition science at Purdue University. "Triglycerides often impart appealing textures to foods, like creaminess. However, triglycerides are not a taste stimulus. Fatty acids that are cleaved off the triglyceride in the food or during chewing in the mouth stimulate the sensation of fat."
In the study, scientists asked participants to group certain solutions together based on taste. Participants had no problem grouping salty, sweet, bitter, sour, and umami tastes, but also designated the “fatty” flavors in a separate unmarked group, without prompting.
"Fatty taste itself is not pleasant… but low concentrations of fatty acids in food may add to their appeal just like unpleasant bitter chemicals can enhance the pleasantness of foods like chocolate, coffee and wine," said Mattes.
Oleogustus: why we might all be getting a new taste for fat
The taste of fat might be joining sweet, salty, bitter, sour and umami as an official sense of the human palate after scientists said they found people have a distinct and basic ability to detect it.
But it’s nowhere near as delicious as it might seem, either in name or nature – they propose calling the new taste oleogustus, after Latin for fat taste, and say that in its raw form it causes people to gag.
A research team at Purdue University in the US tested lookalike mixtures with different tastes. More than half of the 28 special tasters could distinguish fatty acids from the other tastes, according to a study published in the journal Chemical Senses.
Past research showed fat had a distinct feel in the mouth, but when scientists removed texture and smell clues people could still tell the difference.
“The fatty acid part of taste is very unpleasant,” said study author Richard Mattes, a Purdue nutrition science professor. “I haven’t met anybody who likes it alone. You usually get a gag reflex.”
Stinky cheese has high levels of the fat taste and so does food that goes rancid, Mattes said. Yet we like it because it mixes well and brings out the best of other flavors, just like the bitter in coffee or chocolate.
To qualify as a basic taste, a flavour must have unique chemical signature, have specific receptors in our bodies for the taste, and people have to distinguish it from other tastes. Scientists had found the chemical signature and two specific receptors for fat, but showing that people could distinguish it was the sticky point.
Initially Mattes found that people couldn’t quite tell fat tastes when given a broad array of flavours. But when just given tastes that are generally unpleasant on their own — bitter, umami, sour — they could find the fat.
The team started out with 54 people but concentrated on the results from 28 who were better tasters in general.
Robin Dando, a Cornell University food scientist who wasn’t part of the research, praised the study as “a pretty strong piece of evidence” for a basic fat taste, but didn’t like the suggested name — preferring to just call it fat. There is no single scientific authority that names senses.
Complex carbohydrates such as starch are made of chains of sugar molecules and are an important source of energy in our diets. However, food scientists have tended to ignore the idea that we might be able to specifically taste them, says Lim. Because enzymes in our saliva break starch down into shorter chains and simple sugars, many have assumed we detect starch by tasting these sweet molecules.
Her team tested this by giving a range of different carbohydrate solutions to volunteers – who it turned out were able to detect a starch-like taste in solutions that contained long or shorter carbohydrate chains. “They called the taste ‘starchy’,” says Lim. “Asians would say it was rice-like, while Caucasians described it as bread-like or pasta-like. It’s like eating flour.”
The volunteers could still make out this floury flavour when they were given a compound that blocks the receptors on the tongue for detecting sweet tastes. This suggests we can sense carbohydrates before they have been completely broken down into sugar molecules.
When the volunteers were given a compound to block the salivary enzyme that breaks long chains of carbohydrate into shorter ones, they stopped sensing the taste of starch when given solutions containing only long-chain carbohydrates. This suggests that the floury flavour comes from the shorter chains.
This is the first evidence that we can taste starch as a flavour in its own right, says Lim.
Read more: The flavour factory: Hijacking our senses to tailor tastes
Michael Tordoff at Monell Chemical Senses Center in Philadelphia is convinced by the evidence, and says it is impressive. “It will surprise a lot of people,” he says.
Salty, Sweet, Sour. Is It Time To Make Fat The Sixth Taste?
A slice of pork belly, with a thick layer of fat. "If we confirm that fat is a basic taste quality, it's the equivalent of saying chartreuse is a primary color," Richard Mattes of Purdue University says. "It changes our basic understanding of what taste is." Xiao He/Flickr hide caption
A slice of pork belly, with a thick layer of fat. "If we confirm that fat is a basic taste quality, it's the equivalent of saying chartreuse is a primary color," Richard Mattes of Purdue University says. "It changes our basic understanding of what taste is."
Your tongue doubtless knows the difference between a high-fat food and the low-fat alternative. Full-fat ice cream and cream cheese feel silkier and more sumptuous. Burgers made with fatty meat are typically juicer than burgers made with lean meat.
OK, so, we've long known fat gives food a desirable texture. But some scientists are now making the case that we should also think of fat as the sixth primary taste, along with sweet, salt, sour, bitter and umami.
Early in February, researchers from Deakin University in Australia published a paper in the journal Flavour arguing that "the next 5 to 10 years should reveal, conclusively, whether fat can be classified as the sixth taste."
So what would it take for fat to become an official taste?
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"Strictly speaking, taste is a chemical function," Russell Keast, a sensory scientist at Deakin and lead author of the paper, tells The Salt. He says that when a chemical substance – a salt or sugar crystal, for example — comes into contact with sensory cells in our mouths, it triggers a series of reactions. The cells in our mouths tell other nerve cells that they're perceiving something sweet or salty and those nerve cells eventually pass this information on to the brain.
According to the paper, there are five criteria that need to be met to call something a primary taste. It starts with a chemical stimuli (like sugar or salt), which then trigger specific receptors on our taste buds. Then, there has to be a viable a pathway between these receptors and our brains, and we've got to be able to perceive and process the taste in the brain. And finally, this whole process has to trigger downstream effects in the body.
When it comes to fat, scientists know what the stimuli are: fatty acids — the building blocks of oil, butter and lard. And scientists also know that we have taste receptors for these fatty acids in our mouths and intestines.
But researchers have yet to pin down exact how our the receptors on our tongues signal the presence of fat to our brains, though they have some promising leads.
And here's another place where thinking about fat as a taste gets interesting, and controversial: "When we eat something sweet, we have that instant perception of sweetness. With fatty acids, we don't have a conscious perception," Keast says.
In his experiments, Keast says, people usually can't even describe what a solution with pure fatty acids tastes like. "They'll say they know it's different from water, but they don't know why," he says. "We don't have any vocabulary to describe the sensation."
There's one exception to that, says Keast: When food goes rancid, it's usually a sign that mold or bacteria have degraded the triglycerides in oil and lard. We are able to taste fatty acids once they've reached this foul state.
But generally, our inability to perceive fat taste is why some say there's not enough evidence to say fat is a true taste.
If fat is a taste, it isn't like any of the others, says Richard Mattes, a professor of nutrition science at Purdue University, who wasn't involved with the Flavour paper.
"If we confirm that fat is a basic taste quality, it's the equivalent of saying chartreuse is a primary color," Mattes says. "It changes our basic understanding of what taste is."
There's some evidence that fat may meet the criteria of having downstream effects on the body. Fat is a key nutrient that our body wants and needs — and even though we may not perceive fatty acids specifically, there's evidence that the presence of fatty acids on our tongues signals to our digestive system to get enzymes ready to digest fat.
The taste of fat may also signal to our brains and digestive systems that we should eat less, because something caloric and satiating about to make its way down to our guts.
"This may be why low-fat foods have been generally unsuccessful so far," Mattes says. Most low-fat alternatives are designed to emulate the texture of fat, but not the taste — and our bodies aren't fooled by it.
"If we recognize fat as a taste we could start developing better low-fat products," Mattes says, though at this point researchers aren't quite sure what that would entail.
Researchers are also looking into the link between the fatty acid receptors in our mouths and obesity. Preliminary evidence suggests that people who are obese may be less sensitive to the taste of fat, and therefore may feel as satiated by high-fat food.
"We don't fully understand all that yet. But we're close," Mattes says. "The evidence is, in my opinion, quite strong and growing. And I think fat will be accepted as a taste soon."
Fat Is a Texture, Not a Taste…For Now
Creamy…smooth…decadent. We all know how fat feels on the tongue. But is it time to elevate fat from a rich texture to a taste? NPR reports that a group of scientists are pushing for fat to be classified as the sixth primary taste.
A new paper by a group of sensory scientists in Australia makes the case for fat as a primary taste. Russell Keast, the lead author, tells NPR that “taste is a chemical function.” His team cited five criteria that make a taste different from a feeling, including the existence of a chemical stimulus, the existence of pathways that let our brains translate those stimuli and “physiological effects” once our taste buds have been activated.
Fat meets most of those criteria, including the stimulus (fatty acids) and the pathways (via known taste receptors). So why hasn’t fat already taken its place among bitter, sweet, umami, sour and salt tastes? It turns out that humans are pretty bad at perceiving what fat tastes like when it’s not rancid. That leads some scientists to theorize that it’s not a taste at all, but more of a sensation.
But Keast’s team thinks otherwise. They note that fatty acids can activate taste bud receptors, causing people to sense the presence of fat even when they can’t identify its taste. And, given that rodents and people who are less sensitive to fat taste are also predisposed to obesity, they think that fat’s time as a taste is on the horizon.
If fat were to take its place among the primary tastes, it would be the first addition since umami, the savory flavor associated with foodss like seaweed and amino acid-rich soy sauce and cheese. But though Keast’s team predicts it will be only five to ten years before fat is classified as one of the primary tastes, other scientists aren’t so sure. Nutrition scientist Richard Mattes tells NPR that since fat isn’t easily perceived as a flavor, it’s different from the other primary tastes:
If we confirm that fat is a basic taste quality, it's the equivalent of saying chartreuse is a primary color. It changes our basic understanding of what taste is.
How sensitive are you to the taste of fat?
Most of us are well acquainted with the five main tastes: sweet, savoury, salty, bitter and umami.
Feeding Australia: Foods of tomorrow
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But did you know fat has also been identified as a taste, with its own unique receptors?
Fat doesn't provide the same distinct taste as sweet or salt. Instead, it elicits a sensation on the tongue.
And according to Professor Russell Keast from Deakin University's Centre for Advanced Sensory Science (CASS), the more sensitive you are to fat, the less of it you eat.
In other words, the more fat you can taste, the less likely you are to consume it.
But it's also a useful tool for measuring fat sensitivity.
Take this quiz to see how sensitive you are to fat, and what that says about your diet.
Keen to learn more? Watch the first episode of Catalyst's two-part special, Feeding Australia: Foods of tomorrow at 8:30pm on Tuesday, August 14, or catch up afterwards on iview.
Scientists Want To Add Fat To Basic Taste Flavors: Fat-Sensitive Taste Buds May Help Ease Obesity Epidemic
Could fat be the solution to the obesity epidemic? Australian researchers from Deakin University in Melbourne are making an argument for fat’s rightful place as the tongue’s sixth taste profile. In the midst of a worldwide obesity epidemic, researchers are searching for answers every day on how to slow down and stop the growing rates, and this team believes the taste of fat could help. The researchers published their findings in the journal Flavour.
The physiology of fat’s taste dates back to 330 B.C. when Greek philosopher Aristotle examined the tongue’s ability to identify a varied array of tastes. His list included bitter, sweet, succulent, oily, saline, pungent, and harsh tastes, which were divvied up into either aversive or pleasurable. Fat was classified as part of the tongue’s palate because of its texture and ability to release flavors however, it didn’t make the chopping block in modern nutrition.
When Western science decided to recognize umami in 2007, the savory component of a food, to the basic tastes of sweetness, saltiness, sourness, and bitterness, the concept of basic tastes began to expand. When the tongue comes in contact with a particular taste, it sends a message back to the brain that’s either aversive, which includes tastes such as bitter, sour, high salt or it's pleasurable, which includes sweet, umami, low salt, and fat. But for fat to be considered a basic taste of its own, it must fulfill five criteria.
“The evidence now is comprehensive and overwhelming enough to call fat a taste,” the study’s coauthor Russell Keast of Deakin University in Melbourne said. “We have to put a lot more fat into the trials we do for people who are overweight or obese so they are able to identify it, than healthy-weight people. It has this relationship with diet which appears to be very important.”
In the team’s previous research, they studied 500 volunteers’ sensitivity to the taste for fat. They argue that the tongue’s taste buds can detect the presence of fatty acids, and the individual’s sensitivity to fat can predict diet choices. A high-fat diet maximizes the body’s ability to absorb fat but doesn’t change the appetitive, which ultimately throws fuel into the obesity epidemic fire. Our tongues are trained enough to know what fat tastes like, so its absence from food won't slow down our metabolism. By officially declaring fat earned its own place in our taste buds, a person can train himself to slow down on intake with further research.
“When we think about those foods that were put out in the 1990s, low-fat foods that were often failures, maybe it’s as simple as not understanding the role of fat,” Keast said. “You just can’t remove the fat from a food and replace the textural components and replace the flavor release and expect it to be successful because you haven’t matched the taste component, which has all of these other physiological and psychological effects that will affect the liking and acceptance of the food.”
Source: Keast R and Costanzo A. Is fat the sixth taste primary? Evidence and implications. Flavour. 2015.
Learn to Make Any Dish You Cook Better with the Science of Taste
It's happened to us all at one point or another: The dish you've cooked is too salty, too spicy, or perhaps just too. meh. The key to correcting—and preventing—this is balance, when all the flavors of the dish work in harmony. Here's what you should know so you can make fantastic dishes, whether you're working with a recipe or just winging it.
The Science of Taste
As you might recall from your old grade school science class, our tongues are sensitive to basic tastes: sweet, sour, salty, and bitter. Recently, the taste receptor for a fifth basic taste, umami (which means "savory" or "meaty" in Japanese), was discovered by the University of Miami after being heralded in Japanese cooking for centuries . (Ayurvedic cooking also includes two other tastes: pungent, which is hot and spicy like a chili pepper, and astringent, described as " dry and light as found in popcorn ." The image above from WineFolly includes fat as something to consider when pairing food and wine.)
Anyway, the five primary tastes are the key to seasoning dishes well so your food tastes as good as it can. As Jeff potter writes in Cooking for Geeks :
When cooking, regardless of the recipe and technique, you always want to adjust and correct the primary tastes in a dish. There is just too much variability in any given product for a recipe to accurately prescribe how much of a taste modifier is necessary to achieve a balanced taste for most dishes: one apple might be sweeter than another, in which case you'll need to adjust the amount of sugar in your applesauce, and today's batch of fish might be slightly fresher than last week's, changing the amount of lemon juice you'll want. Because taste preferences vary among individuals, you can sometimes solve the balance problems by letting the diners adjust the taste themselves. This is why fish is so often served with a slice of lemon, why we have salt on the table (don't take offense at someone "disagreeing" with your "perfectly seasoned" entrée), and why tea and coffee are served with sugar on the side. Still, you can't serve a dish with every possible taste modifier, and you should adjust the seasonings so that it's generally pleasing.
Why Milk Goes With Cookies—and Every Other Dessert
Long before people were pairing juice with food, beer with cupcakes (there’s a bar in New York City that serves both, seriously), and even wine and cheese, there was milk and cookies. As a kid, you instinctually knew the two went together. But now it’s time to learn the science behind why you crave a glass of milk when you eat something sweet.
For one thing, milk helps blunt sweetness by coating your tongue, so it acts almost like a palate cleanser that clears the way for another bite of that chewy snickerdoodle or coconut macaroon. Plus, recent research suggests that the fat in milk may be the sixth basic taste, called “oleogustus,” and that it can enhance the appeal of desserts by adding to their overall sensory profile. And because flavor is made up of both taste and aroma, dunking your cookies in milk can improve the flavor by helping the fresh-baked scent reach your nasal passages more quickly. This is especially true if the milk is warm, as wet, hot aromas travel faster.
But cookies aren’t milk’s only soul mate. Case in point: Pastry chef Elisabeth Pruitt and her husband, master baker Chad Robertson, offer more than a dozen kinds of cookies at their acclaimed Tartine Bakery in San Francisco. But they actually think that peanut butter and jelly is the ideal treat for pairing with milk. In fact, they love the combo so much, they created their own house-made bread and sweet jelly for this recipe, specifically to be enjoyed with a frosty glass of milk. Here, let them tell you about it:
There are other tried-and-true combos, of course. Milk complements the cocoa and cream cheese in these brownies, for instance, and is a natural fit with anything bittersweet, like chocolate truffles, cocoa soufflés, or chocolate and walnut fudge. But you can also come up with your own spin on the perfect sweet something to serve with milk. To help get your creative juices flowing (and your taste buds watering), consider Chef Watson your own celebrity chef.
A “cognitive cooking” technology developed by IBM, Chef Watson uses flavor algorithms to come up with totally unique combos based on the 9,000-plus recipes in the Bon Appétit database. Think of it like being a contestant on a cooking show, but instead of getting a totally random basket of mystery groceries (elk meat and potato chips, anyone?), Watson suggests only those foods that go together, so the end result is unexpected but also well balanced. All you have to do is enter the ingredients you want to cook with the kind of dish, meal, or course you want to make and what style you’re going for.
Say vanilla is one of your favorite flavors, you have a pint of fresh raspberries that you’d like to use up, and you offered to bring dessert–and a carton of milk–to a friend’s get-together. You just enter “vanilla” and “raspberries” and up to two other ingredients, or you can let Chef Watson suggest them for you. Then choose a dish, like “pudding,” or just a course (“dessert”) and a style (think “party,” “winter,” or even “yard to table”), and you’ll get a list of ideas that you may have never thought of even after a couple of glasses of wine. For example, Watson might suggest marrying vanilla and raspberries with cocoa powder, pine nuts, and turmeric to make a baked-plum dessert. You can follow his directions exactly or just use them as guidelines and go off in your own direction, subbing in a different kind of stone fruit or poaching the plums instead.
When food is cooked, flavor compounds break down into smaller and smaller pieces. Many of these small pieces are broken down so they fit into taste receptors on the tongue. Others are broken down even more until they become volatile. These volatile compounds are released during cooking and when being chewed. While chewing, they make their way through the back of the mouth and up into the olfactory bulb, behind the nose. Think of the volatile compounds as being tiny little keys that can only fit into specific aroma receptors in the olfactory bulb. When these keys are able to make a perfect fit, an aroma is unlocked and sent to the brain to be sensed. As this is happening by the hundreds or thousands during eating, many of these aromas work like musical chords, as if you played a chord on a guitar. These aroma chords become more than the sum of their parts and make up deep, complex aromas. This is why aromas such as vanilla, chocolate and coconut go so well together. This is is also what makes a good wine smell so wonderful there is a huge amount of aromatic data that's working like music on your olfactory bulb. The olfactory bulb can process thousands of aromas at a time, depending on the complexity of the food. The brain actually perceives these aromas as coming from the mouth. That's why taste and smell seem to be one sense when eating food.
So if the mouth can taste five flavors and the olfactory bulb can taste thousands, guess who does most of the work? It's interesting to ponder that the olfactory bulb does the grunt work of flavor perception, even though it feels like you're tasting most of the food in your mouth. This is why when you have a cold, food can taste significantly more bland.