Sensory Preference of Drinking Water Influenced by Subthreshold-Level Mineral Salt Mixtures

This study investigated the impact of subthreshold-level mixtures of KCl and MgSO₄ on the sensory preference of drinking water and identified key sensory drivers. Absolute thresholds were first determined, followed by sensory evaluation of individual and blended salt solutions using a 9-point hedonic scale and CATA test. Design of Experiments (DOE) approach with quadratic polynomial regression optimized the binary mixtures. Results showed samples near the absolute thresholds (0.95 mg/L KCl; 0.65 mg/L MgSO₄) were most preferred. Beyond these thresholds, mineral salt concentration negatively correlated with hedonic rating. Sweetness was identified as a key positive driver, while astringency was a strong negative driver. The significant model revealed a nonadditive effect with a negative KCl × MgSO₄ interaction (antagonism), with a maximum predicted liking of 6.34 at 0.92 mg/L KCl and 0.60 mg/L MgSO₄. These findings demonstrate that subthreshold-level mixtures of mineral salts within a narrow concentration window can enhance water sensory quality by promoting sweetness and suppressing astringency, providing a foundation for developing premium bottled water.