Plastic Straws Sucked for Our Taste Buds
You can’t truly taste things that you can’t smell, scientists have found. And you certainly can’t smell things you’re sucking through a straw.
Suddenly, plastic straw bans have hit a fever pitch.
Initially cast aside by cities like Seattle, the seemingly innocent plastic straw is now rivaling the plastic bag as public environmental enemy number one as businesses from hipster hole-in-the-wall cafes all the way up to Starbucks adopt anti-plastic straw policies to deter customers who might otherwise strangle sea animals in the ocean as they sip and slurp.
(Of course, these efforts to be environmentally conscious has raised a second conflict, that of closing off accessibility to disabled people unable to use the finer motor skills required in chewing.)
While the devastating aspects of the plastic straw on our environment have been dissected at length, one thing that many people haven't realized quite yet is how the very taste of our food could fundamentally change if plastic straws disappear.
That's because the plastic straw is a straight, ineffective bullet to the taste buds that has arguably made food taste worse and less nuanced. That’s, at least, according to Charles Spence, a “gastrophysicist” and author of Gastrophysics: The New Science of Eating famously known for his study on how the sound of crunchiness affects our perception of taste.
Smell is a key to the enjoyment of food, Spence writes in his book. And straws destroy that ability for us to experience beverages in their truest form:
This is especially unfortunate in the case of a freshly ground cup of coffee, given that it is one of the most universally liked smells. Much of the same problem occurs whenever we drink directly from a bottle or can (uncouth as it may be!). Once again, it is the orthonasal olfactory hit that is mostly missing from the experience. We can either sniff the contents or we can drink them, but there is simply no way that we can do both at the same time, no matter how hard we try. And drinking through a straw—well, that is even worse!
Spence goes so far as to write in Gastrophysics that the straw is an obstacle to healthy eating:
The more food sensations you can muster, the better. Stronger aroma, more texture—it all helps your brain to decide when it has had enough. In one of my favorite studies illustrating this point, people consumed far more calories when drinking apple juice as compared to apple puree, and when eating pureed apple as compared to apples. Exactly the same food in all three cases; all that differs are the textural cues the brain receives about how much it has consumed (and how much chewing is needed). This is much the same reason why you should never use a straw to drink. It eliminates all the orthonasal olfactory cues that are normally such a large part of the enjoyment. Be sure to inhale the aroma of your food frequently; after all, this is where the majority of the pleasure resides.
Straws, it seems, muck up how orthonasal olfaction works—and deteriorate our tastebuds’ ability to taste flavors.
That was proven in a 2005 paper published in JAMA, which studied 18 patients who reported loss of their smell sense without reporting a loss of taste. That's key, because, as Spence points out repeatedly in his book, smell and taste are inextricably intertwined in how we experience food.
What the JAMA paper discovered, however, is that while you can still taste food without smelling it (as is the case when using a plastic straw), that taste is fundamentally different from when a person is able to smell and taste food. The fact that the taste is different is key: It's not that sipping soda through a straw makes for a reduced taste experience compared to sipping it without one straw, it's that the straw actually changes the way our brain perceives the taste of the soda.
That might seem simple, but it’s worth noting, especially because one might initially think that straws are straight shots to the taste buds. But that’s not the case at all.
In fact, straws contribute to making food taste bland. It comes down to nasal participation in figuring out taste. Straws and their non-nose taste mechanism is referred to by the scientific community as retronasal olfaction; getting the nasal canal involved is orthonasal olfaction.
"The distinction between orthonasal and retronasal olfaction is that in orthonasal, you smell through your nose, it's what you think about when you think about smelling," said Johannes Frasnelli, a professor of anatomy at the Université du Québec à Trois-Rivières in Canada and one of the authors of the JAMA paper. "The odor source is somewhere in space."
Frasnelli uses the example of a drink, like coffee. Using a straw to drink hot coffee reduces the scent associated with coffee, which is probably why a lot of people don't use a straw to slurp on coffee. (That, and heat will probably melt the plastic.) The "wake up and smell the coffee!" adage, while tired, is true: The combination of the unique smell of coffee combined with the taste most of us love and crave first thing in the morning helps make the experience that much more flavorful. That process of nasal cavities joining forces with our brain to help our tastebuds ascertain the taste of what we are eating or drinking is retronasal olfaction, helping the odor molecules in the back of the mouth clue us into how we taste our food.
That's another thing that bears mentioning: The brain processes tastes differently. Something that smells strongly—perhaps a particularly stinky blue cheese, or a heavily spiced curry—can be automatically put in the tastebud trashcan for its scent. Take your nose out of the equation, though, and that very same food whose odor put a taster off previously might be deemed safe, or even delicious.
And there's societal norms—the manners that were knocked into us during childhood with our parents begrudgingly nagging us to not chew with our mouth open. Sure, that's rude and gross for others to catch a glimpse of, but it also shuts down the pathway by which we can smell our food.
The JAMA study was revolutionary in that the connection between orthonasal and retronasal olfaction had never been analyzed. In particular, how were tastes understood differently by the brain when smell wasn't involved? Taste loss was commonly associated with smell loss, but having perfectly capable tastebuds without a sense of smell was a bit of a medical mystery.
Except, for decades, being able to taste without a sense of smell was something any one who had sucked liquid up through a plastic straw had experienced.
"When you have a straw, you don't have orthonasal effects," Frasnelli said. "When you have a drink—a Coke or a coffee or a cocktail—you sip with your mouth. It reaches the backside and affects our perception."
What the study clearly showed was that flavor was a byproduct of both taste and smell. Taste was only one side of the coin; flavor required smell for the brain to make a fully-formed decision about how a food actually tasted.
And that's something that manufacturers have already capitalized on. Frasnelli points out that wine manufacturers have begun creating wine glasses that create diameters for sipping that involve the ideal ratio between the nose and mouth to maximize taste. It's not new: Contrary to popular myth, the Coke served at McDonald's isn't sweeter or made of a secret, better tasting formula; the straws used to deliver the spurt of Coke onto the tongue are simply wider, hitting more tastebuds and making for a more refreshing burst of flavor. In essence, the bigger straw is attempting to to toggle both the orthonasal and retronasal worlds, something soda manufacturers have long been clued in on with wider tab openings on cans and the return of bottles.
So if plastic straws are on their way to extinction, will we have better tasting formerly-only-sucked-through-a-plastic-straw food? Maybe. It's certainly probable that with a ban people will resort to sipping their drinks over purchasing and using a metal straw, which have seen spikes in sales. The adult sippy cup lids that Starbucks is proposing certainly will be better than straws, though it still falls short of sipping’s ability to tackle the maximum number of tastebuds.
But metal straws present a completely new problem: Introducing metallic taste into the flavor of your food where plastic straws neutrally stood by.
Frasnelli, for one, isn't a fan, saying that the combination of something acidic (think lemonade or tomato juice) with metal makes for an odd-tasting drink. "I don't care for it," said Frasnelli, who’d just returned from a vacation where metal straws were served at a dining location.
Either way, it's officially the dawn of the slurping era.