Introduction
Bottled mineral water is widely consumed globally, exceeding 400 billion liters annually. Its popularity stems from dietary preferences, health concerns, and limited access to potable tap water in some regions. Ensuring the quality and proper classification of bottled waters is crucial to meet regulatory standards and consumer expectations. In this context, electronic tongues offer a cost-effective solution for monitoring and classifying mineral waters based on their electrochemical signatures.
Methods
A portable electronic tongue system, developed by the Perception and Intelligent Systems Research Group at the University of Extremadura, was used. Cyclic voltammetry was performed with a potential sweep from –1000 mV to 1000 mV at 1 V/s using gold screen-printed electrodes. Five commercial mineral water brands were analyzed. For each brand, three bottles were selected, and five replicates were recorded per bottle to obtain representative voltammograms.
The resulting data matrix was evaluated using mean squared error (MSE) to assess repeatability across bottles. Principal Component Analysis (PCA) was applied for dimensionality reduction, and a multilayer perceptron neural network was used for classification.
Results
Low MSE values indicated high repeatability across bottles from the same brand. PCA showed clear clustering by brand, with PC1 strongly correlating with mineralization levels. A single-layer perceptron with eight neurons, trained using the first 20 principal components, achieved 100% classification accuracy across the five brands.
Conclusions
The electronic tongue designed based on a single, non-selective electrode type demonstrated reliable discrimination between bottled mineral water brands. PCA confirmed a strong relationship between electrochemical response and mineralization level. This approach simplifies the traditional multi-electrode setup and presents a low-cost, robust solution and an alternative to commercial electronic tongues/potentiostats for quality control and regulatory compliance in the bottled water industry.
