Electronic language rate Quality of drinks

Device, which simulates the behavior of human taste buds, measures and compares flavors

Electronic language rate Quality of drinks

Device, which simulates the behavior of human taste buds, measures and compares flavors

A collaboration between the Faculty of Food Engineering (FEA) and the Gleb Wataghin Institute of Physics (IFGW) at Unicamp has been testing and applying electronic tongue-type equipment to evaluate the quality of various types of beverages. This device, composed of an array of chemical sensors, simulates the behavior of human taste buds and aims to measure and compare flavors and other types of substances present in food.

Although electronic tongues are already widely known in the scientific literature, the partnership between the two institutes aims to test sensors developed at Unicamp itself, based on impedance spectroscopy. Still little used in beverage analysis, this technique measures the behavior of different materials by studying a system's response to the passage of an alternating electric current. In electronic tongues, each impedimetric sensor reacts differently to the substances present in the beverage, creating, together, a unique pattern of electrical responses that generates a kind of fingerprint of the beverage.

“The human tongue works with the concept of global selectivity. If we drink coffee, hundreds of molecules send a flood of information to the brain, which groups them and recognizes them as coffee. The device tries to mimic this ability, so the choice of materials that form the sensory units is fundamental to extracting as much information as possible,” explains IFGW professor Antonio Riul Jr. The professor was the first researcher to employ impedance spectroscopy in electronic tongues, when he was doing postdoctoral work at Bangor University in Wales (United Kingdom), and his analyses demonstrated that the simplicity of the device allows the extraction of large volumes of information, compared to traditional technologies.

Although it has applications in various types of research, such as soil analysis, in the food industry the impedimetric electronic tongue aims to complement sensory analysis performed by humans, as well as physicochemical measurements, which tend to be costly and time-consuming. By using data analysis algorithms that create classification and prediction models of substances, the tongue does not need standards—reference sensors to compare results obtained—which speeds up and reduces the cost of the process. Furthermore, the device has been adapted to measure samples continuously, using a microfluidic sensor system.

According to FEA professor Douglas Fernandes Barbin, this adaptation is beneficial because the more traditional voltammetric electronic tongue requires analyses to be performed later in separate containers. However, in a future industrial application of microfluidic technology, there is the possibility of performing the analysis for continuous quality control of food. "This would speed up the process because it allows for correcting an error during the production of a juice, for example, instead of analyzing the final product and, if an error is identified, having to discard the entire batch that has already been processed," he explains.

Results

In his laboratory, Barbin leads the research group. Food Process Analytical Technology, which studies technologies for food and agricultural product processing. The team excels in analyses using optical methods, such as near-infrared spectroscopy (NIRS), which illuminates the sample with this radiation, measuring which frequencies are absorbed. However, liquids are usually translucent, and some foods contain particles that modify the path of light in the medium, making NIRS analysis difficult. It was this difficulty that inspired the partnership between the two institutes, which began when the FEA professor discovered Riul's studies with soil analysis.

The first proof-of-concept study of the prototype's use in liquid analysis has just been completed by researcher Tatiana Américo da Silva. In her doctoral thesis, defended in Food Engineering, the author evaluated the device's performance in measuring the quality of three popular beverages in Brazil: coconut water, grape juice, and cachaça. The study concluded that the more complex the liquid, the more samples and physicochemical analyses are needed, but that acidity and sweetness—represented by total soluble solids—had a significant influence on the measurements, being the two characteristics that stood out most in the analyses.

In the case of coconut water, for example, being the beverage with the fewest complex compounds, the device identified the total soluble solids, the total titratable acidity (which refers to the total amount of acids in a sample), and the pH values, in addition to being able to differentiate between brands that had undergone processing. For grape juice, however, the tongue was more effective only in determining pH values, also separating whole samples from reconstituted ones. "As for alcoholic beverages, the tongues grouped samples of sweetened cachaça and gin, but only one of the systems tested grouped by pH, while the other grouped by total soluble solids and alcohol content," reveals the author.

These results demonstrated that the sensors have potential for application in liquid differentiation, but further studies with a larger quantity and variety of samples are still needed before the technology is ready for industrial application. In this sense, one of the challenges is the durability of the electrodes, since prolonged measurements lead to the formation of a biofilm on the sensory units, which need to be replaced periodically. This wettability control is the focus of a study that is still being developed at IFGW and, if successful, could extend both the lifespan and availability of the device.

Another need is to compare the measurement results using the electronic tongue with those obtained in human sensory analysis, which is being conducted by FEA doctoral student Dhanus Raj Kanaga Raj. The study is yielding promising results and focuses on the analysis of pharmaceutical products and food flavors such as coffee, tea, and juice. "One of the objectives is the quantification of different types of sweeteners, since now all these products come with sugar or sweeteners," reveals the researcher, who is expected to defend his thesis by the end of 2026.