Could the Electronic Tongue Save Us From Bad Coffee?

An Israeli college has replaced human tasters with a high-tech one that, in addition to developing the perfect pomegranate drink, could boost agricultural exports and more.

Dror Miller

Yecch. That coffee tasted awful. You can’t say exactly why – it wasn’t too bitter, for instance, but you just didn’t like it. But the Electronic Tongue at Tel-Hai College, Upper Galilee, would have known exactly how to analyze that coffee and define its taste. Put otherwise, the e-tongue ascribes a digital taste fingerprint.

Electronic tongues have more practical uses, like choosing the sweetest pomegranate strain, or quickly, reliably and cheaply outing fake olive oil, points out Dr. Ofir Benjamin, head of the Tel-Hai Organoleptic Laboratory, which studies the correlations between food composition and the consumer experience. More conventional and much more expensive analytic methods such as HPLC (high performance liquid chromatography) may fail to notice when some of that gorgeous olive ooze has been replaced with cheap canola, he says.

Human tongues are subjective and unreliable. Before the advent of advanced machinery, food companies and the like had to rely on tasters, who could have good days, bad days or a common cold that would make everything taste like cat food.

Another way in which people are unreliable as taste analysts is that over time, it’s not only our skin elasticity that diminishes, but also the number of receptors on our tongues, says Benjamin. “That explains changes in the intensity with which we taste things. Older people need more taste stimulation. The e-tongue is also more sensitive than the human tongue. It can identify molecules at lower concentrations than our tongues can.”

Tel Hai’s e-tongue, bought from the Japanese company Intelligent Sensor Technology in July 2014, is the only one in the Middle East, the college says. It cost half a million shekels (around $125,000), much of which was donated by ICA in Israel (JCA Charitable Foundation). It doesn’t have bad days and doesn’t get fatigued.

Droro Miller

You say tomato, I say it tastes sweet

There are different types of electronic tongues, but their common function is to detect the molecules that we taste. Tel-Hai College bought an e-tongue developed by Prof. Kiyoshi Toko of Kyushu University. It has sensors – think like ice pop sticks – coated in membrane lipids, which are a group of charged large fatty molecules. Each “stick” is coated with a different lipid composition, which can detect different taste molecules.

So, the lipid-coated sticks are immersed into a sample liquid, like olive oil or that grotty coffee. The taste molecules bind with the lipids that can detect them. When that happens, an electric signal is created. The final output is a readout specifically analyzing the molecules contributing to the product’s taste. No subjectivity there.

So, you could take juices made from five types of apples and ask tasters which they like best, and get five different answers. Or you could use the e-tongue to objectively test which has the characteristics you want in the juice – for example, which is the sweetest, yet with a tart tang to keep the flavor interesting.

How not to ruin fruit in storage

Dror Miller

Though food companies are starting to sniff at the device, the Organoleptic Lab bought the beast for its own academic purposes: the study of food, its processing and storage, some done in collaboration with other academic institutes.

“Take storage,” explains Benjamin. “Today the goal is to store fruit and vegetables for as long as possible while maintaining their quality, for instance to store summer-grown fruit to sell in the winter, which involves monkeying with temperature, humidity and ethylene antagonist molecules, too. But all that affects taste. We can check how, reliably, using the e-tongue, and work out the best way to store the produce with minimal impact on taste.”

What about that half-million-shekel price tag? Human tasters are not only less reliable: They cost a fortune, not only in salary but to train, Benjamin explains. “It took me half a year to train a group of 10 people to be ready to perform professional sensory analysis. This means the subjects needed to be thoroughly familiar with the complex sensory attributes of the object research.”

Also, he points out that the Health Ministry itself has commissioned Tel-Hai, which has the only cheese lab in the country, says Benjamin, to use the e-tongue for research on how to lower the salt content in certain cheeses without ruining their taste and texture. No, the e-tongue can’t tell if their smell changes, but Tel-Hai, with collaboration with the MIGAL research institute should be getting an electronic nose from England in a couple of months, he adds.

Growing in Galilee and optimal pomegranates

Some entertain hope that the e-tongue can not only boost Israeli agricultural exports, including off-season delicacies, but also the entire north of Israel, economically speaking at least. In addition to farming, other major growth industries in the Galilee such as food processing and storage, and the development of ‘medical foods’ could benefit from this high-tech taster.

Note ye that the e-tongue isn’t infallible. “There are molecules that it can’t identify,” admits Benjamin. Its detection facility is based on the electrical charge of the taste molecules, and if a given taste molecule has no charge, well, too bad. We may taste them but the machine can’t. It also tends to fall down on non-sugar sweeteners, which we notice but it doesn’t, he says, adding: “I believe that in the near future, we will see more development in advanced sensors, that will be able to detect those missing taste signals.”

But when it comes to comparing Product X with Product Y, it can tell us the differences in taste profile according to food composition. “Take pomegranate juice. I tested different types of juice developed at the Agricultural Research Organization/ Volcani Center, and showed that the tongue distinguished between their different taste profiles. Taste tests showed that people want a little sour and a lot of sweet in their pomegranate juice. With our test, we can see which pomegranates have the best taste profile, helping the juice maker connect to the right pomegranate growers,” Benjamin says.

And maybe one day, Israel will be like the Japan – where shoppers can already choose groceries based on accurate taste guidance maps made by the e-tongue.