The human tongue is a pink, undulating, fleshy affair covered in thousands of papillae—all the better for sensory perception. If the tongue weren’t so ordinary, it would be strange to think of such an appendage taking up most of the room in your closed mouth, allowing you to discriminate the foul from the toothsome.
But there it is.
And here I am in Room 150 of the Food Science and Human Nutrition Building on the Pullman campus, one of eight panelists who will smell and drink wine after wine after wine over the course of two weeks. Kenny McMahon, a doctoral student, is our overseer, handing us these wines, but he can’t tell us what we’re tasting or why—this is science, after all.
My tongue gets a workout with each new glass, but it’s nothing compared to the marathon tasting the electronic tongue does in the lab next door.
The e-tongue looks like a sophisticated little cyborg squid dipping its tentacles in shot glasses of wine. A machine of metal, glass, and plastic, it moves, whirrs, and communicates with a computer. To the point, it’s a multisensory array coated in specific membranes that interact with ions in solution. Unlike me and my easily-fatigued gustatory organ, the e-tongue can taste and characterize 60 different wines in a little more than two hours.
The $90,000 tongue has been busy since Carolyn Ross, food scientist and head of the Sensory Evaluation Unit, purchased it two years ago. The hallway passing by the sensory labs and leading to Ross’ office is overflowing with poster abstracts based on work done with the e-tongue.
“Prior to this we had the capability to look for volatile compounds which contribute to flavors. Those are things like strawberry, vanilla, and oaky,” Ross says, her slight Canadian lilt exposing her provenance. “But we didn’t have any one instrument testing analytically for taste: sweet, sour, salty, bitter, umami.”
These are things we can all sense with our own perfectly functioning tongues. But the e-tongue can distinguish flavor on a molecular level. “The human tongue doesn’t look at little things absolutely individually. We take everything together,” Ross says. We sense taste, flavor, aroma, and mouthfeel all at once, and we have trouble teasing these sensations apart. “That’s what the e-tongue does,” says Ross.
Back in the sensory lab, my fallible tongue and nose are struggling with each wine. This day, in the second week of tasting as we’re preparing to sniff and gargle red varietals, we’re trying out “control” scents, attempting to agree on how to rank the plastic and the burnt rubber components, just two of ten parameters we’ll smell and taste for. McMahon tells us he used fewer burnt rubber bands for this control scent compared to the last, but left them soaking for longer, which may account for the change in intensity. For such a sophisticated libation, it’s an unsavory task. I groan a little inside with each sulfuric whiff.
The e-tongue has no capacity for groaning. That’s the point, says Charles Diako, a doctoral student who was trained by Alpha MOS, the e-tongue’s France-based manufacturer.
“We have some form of subjectivity in the human sensory evaluation,” Diako says. “The way you taste wine today depends on your mood. If you are very angry today, maybe the wine doesn’t taste as sweet to you. Maybe. Tomorrow if it’s snowy and you don’t want to come here but you do, the wine is bitter. It’s subjectivity in human evaluations. Bring in the electronic tongue, and it gives you the absolute values. The whole thing is to bring objectivity into sensory science.”
And it does. The human tongue can tell when a wine is sweet. The e-tongue will tell how much sweetness a wine contains.
Ross, on the other hand, is careful to point out that the e-tongue will never replace a trained panel of expert tasters. But trained tasters are rare.
“The trained panels need a lot of training before you can consider them reliable instruments,” Ross says, emphasizing a lot. “At least a hundred hours of training. That’s not to say that 12 hours isn’t sufficient to reduce the variability and have people agree on certain attributes. That’s always the trick of the training, getting people to agree on what an attribute is and its perceived intensity.”
Under McMahon’s watch, we are given a scale from one to 15 for ten attributes, and we all have to agree on them, just as Ross was saying. We smell for reduced and oxidized characteristics. We seek out vegetal, floral, and overall fruit. We dig for musty and earthy. We sip it like soup and aerate it. How sweet and sour and bitter is it? What about the mouthfeel? Does it burn? Is it astringent? Is it thirst quenching? A strange question to ask about a wine you’re spitting into a red plastic cup at 10 a.m., but we do our best to find common ground.
Still, with every sip I can’t help but feel I’m competing with the e-tongue, that my flawed human tongue will never win against the machine next door. Diako doesn’t discount this thought.
“If we have objective measurements of what we are looking at, then this can be disseminated into industry, into the farmers and grape growers so they can tailor their activities to what they want to optimize,” he says. “That way we can also give authentic information. I’m not saying the sensory human isn’t authentic, but…” He laughs without finishing his thought.