Abstract 
 
 It is widely accepted that humans can taste mono- and disaccharides as sweet substances, but they cannot taste longer chain oligo- and polysaccharides. From the evolutionary standpoint, the ability to taste starch or its oligomeric hydrolysis products would be highly adaptive, given their nutritional value. Here, we report that humans can taste glucose oligomer preparations (average degree of polymerization 7 and 14) without any other sensorial cues. The same human subjects could not taste the corresponding glucose polymer preparation (average degree of polymerization 44). When the sweet taste receptor was blocked by lactisole, a known sweet inhibitor, subjects could not detect sweet substances (glucose, maltose, and sucralose), but they could still detect the glucose oligomers. This suggests that glucose oligomer detection is independent of the hT1R2/hT1R3 sweet taste receptor. Human subjects described the taste of glucose oligomers as “starchy,” while they describe sugars as “sweet.” The dose–response function of glucose oligomer was also found to be indistinguishable from that of glucose on a molar basis. ||||| Scientists have found evidence that humans can pick up a sixth taste associated with carbohydrate-rich foods. 
 
 Not only could the discovery see a new flavour added to the list of tastes, which currently includes salty, sweet, sour, bitter, and umami, but the findings might also explain why we love such starchy foods so much. 
 
 "I believe that’s why people prefer complex carbs," lead researcher Juyun Lim from Oregon State University told Jessica Hamzelou from New Scientist. 
 
 "Sugar tastes great in the short term, but if you’re offered chocolate and bread, you might eat a small amount of the chocolate, but you’d choose the bread in larger amounts, or as a daily staple." 
 
 Lim and her colleagues gathered 22 subjects, and had them taste a bunch of different solutions made up of different levels of carbohydrates. The subjects were asked to rate how each tasted. 
 
 "They called the taste 'starchy'. Asians would say it was 'rice-like', while Caucasians described it as 'bread-like' or 'pasta-like'. It’s like eating flour," Lim told New Scientist. 
 
 Next the subjects were given a special compound that specifically blocked the receptors on their tongues that picked up sweet tastes, and then a compound that blocked the enzyme that breaks down long-chain carbohydrates. 
 
 This step was crucial, because until now, the consensus was that humans couldn’t detect the taste of carbs. The notion was that because carbs break down so rapidly, only a sweet taste was left over from the sugar molecules that make them up. So when we taste carbs, previous research suggested we only taste sweet. 
 
 After the blockers were administered, the subjects were still able to taste and describe the starchy flavour, leading Lim to conclude that humans are specifically able to taste carbohydrates. 
 
 "Every culture has a major source of complex carbohydrate. The idea that we can’t taste what we’re eating doesn’t make sense," Lim said. 
 
 The results also suggest that the newly found taste might be the reason why humans love to eat carb-rich foods like bread and rice, which have a long history as part of human culture. 
 
 Now, with a solid hypothesis to build on, the team hopes to identify the specific receptors on the tongue that are responsible for picking up the sixth taste. 
 
 'Starchy' isn’t the only new taste that scientists are investigating. 
 
 Back in 2015, researchers in the US found evidence that fat might be its own taste, saying that on its own, fat is a rather dull taste, but it works to amplify other flavours in the same way that bitterness does. 
 
 Another team is looking into the possibility that tastes like calcium, blood, and amino acids might be separate as well. 
 
 Regardless of whether or not these new 'tastes' make it in to the official list, it's clear that we still know very little about our own mouths and senses. Hopefully, we'll one day fully understand one of the most fundamental aspects of our daily lives: eating. 
 
 The team’s work was published in Chemical Senses. ||||| Scientists want to add a sixth basic taste to describe how we experience the flavours of bread, rice and other carbs. Will it help explain why we like certain comfort foods? 
 
 Age: Old and new at the same time. 
 
 Appearance: Kind of, you know, starchy. 
 
 Uh-oh, starchiness doesn’t sound good. It doesn’t? 
 
 No! It sounds old and fusty, and buttoned-up, and bad for you. Well tough luck, because starchiness is the hot new thing in food. In fact, it’s likely to become a new primary taste. 
 
 Like sweet and salty and bitter and sour? And umami, yes. 
 
 I could never work out what umami actually is. It’s umami-ish. Not salty or bitter but also both of those things. Beef is umami. Parmesan is umami. Mushroom is umami. Please don’t make me go through this again. 
 
 Right, I get it. Potatoes are umami. No, you idiot. Potatoes aren’t umami. Potatoes are starchy. That’s a completely different taste profile entirely. 
 
 Oh God. No, really, it is. The journal Chemical Senses has published findings by Prof Juyun Lim of Oregon State University. She claims that the starchy taste of carbohydrates – bread and pasta and rice and potatoes – is distinct enough to warrant a place at the primary taste table. 
 
 Really? So you’re saying that soon it will be sweet, salty, bitter, sour and ... potato? And umami, yes. 
 
 I bet you’re the sort of person who uses the word “mouthfeel” sincerely, aren’t you? Anyway, this is potentially quite an important discovery, because it might reveal why we find starchy foods so comforting. 
 
 Umami: why the fifth taste is so important Read more 
 
 And then what? And then, I don’t know, Heston Blumenthal will make a new TV series about starch and it will be called “Heston’s Perfect Starch”, and it will show him labouring for three years to make a bloody potato sandwich that perfectly encapsulates the memory of him getting lost on a beach in 1971, or whatever. 
 
 That came out of nowhere. Well, I mean this is getting out of control, isn’t it? Everything used to be so easy. Sweet, salty, bitter and sour used to cover everything. But umami has ruined it all for everyone. Now rice gets to be a primary taste? Whatever next? Eggs? Coco Pops? Marmite? 
 
 Marmite is umami. I know Marmite is umami. I’m the umami expert, remember? 
 
 Do say: “I’m getting hints of King Edward, followed by a great wash of Hovis Granary Batch.” 
 
 Don’t say: “I would like to return this salad. It isn’t starchy enough.” ||||| Jonathan Knowles/Getty 
 
 As any weight-watcher knows, carb cravings can be hard to resist. Now there’s evidence that carbohydrate-rich foods may elicit a unique taste too, suggesting that “starchy” could be a flavour in its own right. 
 
 It has long been thought that our tongues register a small number of primary tastes: salty, sweet, sour and bitter. Umami – the savoury taste often associated with monosodium glutamate – was added to this list seven years ago, but there’s been no change since then. 
 
 However, this list misses a major component of our diets, says Juyun Lim at Oregon State University in Corvallis. “Every culture has a major source of complex carbohydrate. The idea that we can’t taste what we’re eating doesn’t make sense,” she says. 
 
 Floury flavour 
 
 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. 
 
 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. 
 
 Taste test 
 
 The finding adds to growing evidence that human taste is more complex than thought. “Many people think there are only five tastes, but a bunch of us think there might be others,” says Tordoff, who is investigating whether we might be able to specifically taste calcium. 
 
 Other potential tastes being investigated are the flavour of carbonated drinks, the metallic taste you get from blood, and amino acids, the building blocks of proteins. Receptors have been found for kokumi, a full-bodied flavour that has been described as “hearty” and is thought to make foods feel richer and more satisfying, and there is some evidence that we can taste the fatty acids that make up fats. “We are moving away from the idea of five primary tastes,” says Lim. 
 
 But before any new flavours can be enshrined as primary tastes, they must meet a strict list of criteria. Tastes need to be recognisable, have their own set of tongue receptors, and trigger some kind of useful physiological response. 
 
 Starch doesn’t tick all of these boxes yet: Lim and her colleagues are yet to identify specific starch receptors on the tongue. Kokumi has not so far made the list because people who eat it can’t put their finger on a specific taste. 
 
 One criterion is that a flavour must be useful to us. There’s a strong case to be made for starch here, which is a valuable slow-release energy source that is worth detecting. 
 
 “I believe that’s why people prefer complex carbs,” says Lim. “Sugar tastes great in the short term, but if you’re offered chocolate and bread, you might eat a small amount of the chocolate, but you’d choose the bread in larger amounts, or as a daily staple.” 
 
 Journal reference: Chemical Senses, DOI: 10.1093/chemse/bjw088
– Wondering why a bread bowl full of pasta with fries on the side sounds like it would really hit the spot right now? It could be a heretofore unknown sixth taste that a group of scientists claims to have discovered, Science Alert reports. Up until now, the five tastes humans were known to be able to sense were sweet, sour, salty, bitter, and umami. According to New Scientist, it might be time to add "starchy" to that list. Researcher Juyun Lim notes that "every culture has a major source of complex carbohydrate," be it rice or pasta or potatoes, and it "doesn't make sense" that humans wouldn't be able to taste those. But because enzymes in our mouths break carbohydrates down to simple sugars, scientists always assumed we were just tasting sweet. Lim disputes that in a study published in Chemical Sense. She found that people could pick out a solution containing carbohydrate chains—it tasted "like eating flour"—even when given a compound that blocked their tongues' sweet receptors. That indicates that starchy is its own taste. It makes evolutionary sense that humans would be able to taste starch, which is an excellent source of sustained energy. And this could also explain why we find starchy foods comforting, the Guardian reports. However, Lim and her team still need to find starch receptors on the tongue in order to qualify it as a primary taste. Other scientists are looking into the possibilities that fat, calcium, blood, and more are their own tastes. (Penguins can't taste the fish they eat.)