Apple juice quality control using the voltammetric electronic tongue and chemometrics

The authentication and safety of polyphenol rich fruits necessitates rapid and reliable assessment tools. Consequently, a voltammetric electronic tongue made from modified epoxy-graphite electrodes is employed to evaluate apple juice across spoilage, adulteration, and varietal differentiation scenarios. Through sensor optimization, three key sensors, the ones modified with SnO 2 and Ag nanoparticles and the one modified with cobalt(II) phtalocyanine redox catalyst, are identified from an initial pool of eight, enabling accurate polyphenol analysis. Principal component analysis (PCA) is used to reveal qualitative distinctions among the samples, and euclidean distance quantifies the degree of adulteration based on the same dataset. Partial least squares discriminant analysis (PLS-DA) classifies apple varieties (100% accuracy), and partial least squares regression (PLSR) predicts hours in spoilage studies ( R 2 = 0.99). Combining data from all experiments, the PLSR model predicts total polyphenol content (TPC) with remarkable accuracy ( R 2 = 0.99). These findings demonstrate the potential of the voltammetric e-tongue as a cost-effective and rapid tool for assessing the chemical profile of apple juice, offering a scalable solution for quality evaluation in polyphenol-rich beverages. • Voltammetric e-tongue was used for qualitative and quantitative apple juice assessment • Differentiation of apple varieties, spoilage and adulterants was performed using PCA • Prediction of apple juice freshness (time) was performed by e-tongue • Quantification of total polyphenol content in apple juice was performed by e-tongue • Euclidean distance linearly quantifies separation of pure and adulterated apple juice