‘Electric tongue’ may improve beverage sampling

An electronic tongue could be used as a reliable and cheap alternative for the real-time quantification of fructose and glucose in samples of commercial soft drinks, according to new research.

The study, published in the journal Sensors and Actuators B: Chemical, reports researchers from the Polytechnic Institute of Bragança, Portugal, developed and tested an electric tongue chemical sensor for the analysis of non-alcoholic beverages.

“The device is versatile, allowing cross-information as well as specific information about this type of liquid sample matrix,” said the authors, led by Dr Luís Dias.

“The device was successfully applied for semi-quantitative discrimination of real juice soft drinks, based on the added fruit level,” they added.

Product analysis

“Nowadays, consumers are very concerned about the quality, aroma and flavour of the different types of these beverages, for instance of fruit juices. Therefore, soft drinks producers seek to keep their products within very tight quality standards, including the flavour of the products,” explained Dr. Dias and his colleagues.

They noted that in order to guarantee that specific beverages fulfill pre-established chemical and physical parameters, industry uses sophisticated equipment and technical expertise for sample preparation. However, for sensory analysis still requires a considerable amount of resources, time and money as panels of trained technicians are needed.

“Hence, it is important to develop and test new methodologies as faster, low cost and reliable alternatives to these expensive and time-consuming determinations,” said the researchers, noting that electronic tongues may provide such alternatives.

Electric tongues and noses are not new technologies, and have previously been used to test for specific chemical constituents of products. The researchers said that their new electric tongue may offer the possibility of testing a wider range of sensory parameters.

Study details

The researchers tested a total of 16 commercial fruit juices from five different brands. In a semi-quantitative approach, the signal profiles recorded by the electronic tongue sensor were used to differentiate four beverage groups with different fruit juice contents: more than 30 per cent juice, 14 to 30 per cent, six to ten per cent, and less than four per cent juice.

Dias and his colleagues reported that the model explained 99 per cent of the total variability of experimental data, and was able to classify the studied samples into the correct group with an overall sensibility and specificity of 100 per cent for the original data, and greater than 93 per cent in a cross-validation procedure.

“The observed analytical performance suggests that electric tongues could have a wider set of applications,” said the researchers.

Source: Sensors and Actuators B: Chemical