Robotics has found its place in the coffee industry in manufacturing and coffee preparation, but what about taste? GCR discovers a new device that can analyse taste numerically and puts human cuppers to the test.
For centuries, roasters have relied on the human palate to distinguish flavour characteristics, but thanks to Japanese company Intelligent Sensor Technology (Insent), there’s a new product on the market matching the sophistication of human taste.
Called the Taste Sensing System, this patented machine uses sensors which mimic the function of the human tongue to convert tastes into numerical data.
On the tip of each sensor is an artificial lipid membrane, pre-treated in a solution of tasteless potassium chloride, intended to simulate human saliva. Each sensor is engineered to capture one of six taste factors as well as any aftertaste: sourness, saltiness, umami, bitterness, astringency, and sweetness.
The sensors on the ends of finger-like rods are dipped into cups of sample coffee. Each lipid membrane reacts with a different flavour carrier on the membrane surface. First, the sensors are immersed in the tasteless solution to obtain reference potential, then move to the sample coffee to identify each taste factor found in the “initial taste” phase. The sensors are then immersed in the solution again to obtain a ‘difference between’ or CPA value – a change of membrane potential caused by adsorption. This provides data regarding the strength of bitter and astringent substances commonly found in the “aftertaste”. Tastes are detected via electric signal, analysed by computer, and presented as a numerical value in just one hour.
German-based roasting machine manufacturer Probat was introduced to Insent’s Taste Sensing System in 2019 after scanning the market for new tools that could help improve its work and that of its customers. This technology was awarded the 2017 Best New Product by the Specialty Coffee Association for the accuracy and consistency of its TS-5000Z Taste Sensing System, and the Probat team are experiencing why.
Keen to prove how helpful the tool actually is, Probat’s Technology and Training Chemical Engineer Sandra Bongers conducted an initial trial of the Taste Sensing System. She made five roast coffee samples of different colour grades (light and dark profiles).
From the roast, Bongers prepared 500 millilitres of filter coffee and used just 70 millilitres for each sensor sample. Probat’s cupping panel tasted the same roast samples.
Probat Chief Technology Officer Thomas Koziorowski says the results from the sensor proved to have a high correlation with those of the human sensory evaluation.
“In a regular human cupping experience, a typical spider graph of flavours is used. A human can go deeper in their explanation of acidity, such as citric acidity or describe floral, nutty notes. But what this technology does, is identify the main taste characteristics with a base direction to compare your results. It can optimise not only taste but the quality of your blend,” Koziorowski says.
Bongers adds that the sensor unit measures flavour descriptions as a number, so it’s easy to assess any variance in taste levels compared with a human cupping panel.
Probat also tested coffee samples of different roast length: short, medium, long, as well as using different roast profiles on different roasting equipment, including the Probat Jupiter tangential roaster and Probatino drum roaster.
“Most roasters in the market know that if you have a longer roasting time, you lose acidity and in a shorter roast time you gain acidity, and that’s what we saw in the sensor results too,” Koziorowski says.
“We also tested the consistency of the whole sensor system. We measured the samples twice, then three times, and four times and we always got the same reliable results. It really was astonishing and brilliant to see the high consistency of results.”
Bongers went one further, measuring and comparing samples up to 20 times to see if there was any discrepancy or change in results. “When I saw how good it was, I thought, ‘wow, ok, I trust the sensor results. It means I only need one sample as a comparison for future tests,” she says.
For Koziorowski, what was surprising was the clear display of results and a real direction of taste descriptors.
“This tool makes a general calibration and what we get is an easy comparison of data that gives us a first, clear, base line direction when talking about flavour such as acidity or astringency of coffee,” he says.
“Such technology could be really helpful when comparing the quality of roast or blends, especially the fine tuning of roast profiles or development of new recipes – that’s a big point. Larger multinational companies may also want to compare roasts in different countries, so it’s a helpful tool. Instead of sending samples around the world you can have an instant comparison of results.”
In terms of operation, Bongers says the sensor is very easy to control, with only one person needed to conduct the testing.
“It is easy to handle but it’s useful to know about chemical and analytical things. Taking a sample is very simple. I just brew a filter coffee, take a sample, and it’s measured,” she says.
“Normally when I roast, I conduct a cupping of the coffee the next day. With the sensor, I can measure it automatically overnight, so that when I arrive the next morning, I have results before the human cupping panel has started. It’s a first check of how the acidity is tasting, or the level of bitterness or aftertaste. It’s the first real piece of evidence to tell you what has happened in your roast and I think that’s very important for the quality control of a blend because cuppings are not always on the same day as the roast.”
In a world that continues to work from home and has strict guidelines around hygiene, the Taste Sensing System is also the perfect solution when it’s difficult to get a team together for a cupping.
While it can’t detect aroma – an idea that may not be too far from reality – Koziorowski says it is the ideal accompaniment to a human cupping panel for advanced quality assurance.
“Maybe in a few years, or 100 years, we might see technology replace the human palate, we don’t know precisely if or when because technology is always changing,” he says. “It’s up to individual companies to question if they rely on their people and their cupping boards or the technology. For us, at this point, the sensor is a tool that supports our staff and their results.”
Where it will be helpful, Koziorowski says, is to show consumers accurate images of taste descriptions, assist product development, provide objective sensory evaluation, and manage advanced quality control without well-trained sensory testers or expensive analytical instruments.
The technology is already commonly used in the pharmaceutical, beverage, and food industries. To date, more than 600 devices are in use, with 25 of them at coffee roasting plants in Japan.
When it comes to research and development, Probat is always looking into new equipment and opportunities to enhance its coffee roasting equipment. This is evident by the introduction of Internet of Things technology and the establishment of software solutions company fabscale to support roasting customers with data management and analysis.
“We are always looking at what new technology makes sense to develop on our roasters to help enhance roasts and cup quality, and this sensor may be the next step in developing such equipment in the future. We are already thinking how we can better link sensory data into our new roaster control systems,” Koziorowski says.
“We want to continue helping our customers in the right way and find solutions to their problems.”
For more information, visit www.probat.com/en