Application of an electronic tongue for taste assessment of some brands of commercially available milk in South Africa: A comparative analysis

Abstract

• Electronic tongue distinguished the taste profiles of 16 commercial milk samples • UHT milk showed better taste and palatability compared to ultra-pasteurized milk • Full-cream milk retained better palatability than low-fat milk during storage • Refrigeration significantly slowed taste deterioration vs. room-temperature storage • >96% PCA variance, confirms electronic tongue accuracy for monitoring milk quality This study investigated the feasibility of using an electronic tongue (E-tongue) as an objective analytical tool for evaluating the taste of commercial liquid milk brands in South Africa. Sixteen samples from four brands were analyzed using a potentiometric E-tongue equipped with cross-selective taste sensors, calibrated to detect sweet, sour, salty, bitter, and umami responses. The effects of storage temperature (2°C–19°C), heat treatment (ultra-pasteurization vs. ultra-high temperature, UHT), lipid content (full-cream vs. low-fat), and storage duration (0-, 3-, 5-, and 45-days post-opening) on taste perception were examined under controlled conditions. Principal Component Analysis (PCA) of multivariate data successfully differentiated milk samples and identified key taste attributes that contribute to variations in palatability. The E-tongue effectively distinguished taste differences between brands, with cumulative variance contributions of 96.007% and 97.898% for PC1 and PC2, respectively, on Days 0 and 45. The results indicate that the E-tongue effectively monitors quality and detects spoilage under various storage conditions and processing methods. UHT milk had a better taste profile than ultra-pasteurized milk, and full-cream variants retained better palatability than low-fat counterparts throughout storage. Refrigerated storage markedly slowed taste deterioration relative to room-temperature conditions. Supporting physicochemical analyses, including pH, viscosity, titratable acidity, particle size, and polydispersity index, confirmed E-tongue results and identified age-gelation in specific samples by Day 45. The Alpha Astree II E-tongue effectively characterized taste profiles and distinguished both inter- and intra-brand differences during storage. The findings demonstrate the potential of the E-tongue as an objective, rapid, and reliable instrument for assessing milk quality, facilitating product development, and improving sensory evaluation methods within the food industry, especially in areas with inconsistent cold-chain infrastructure.