Optical Fingerprint Database of Beer Brewing Water Based on Supramolecular Probes and Its Application in the Evaluation of the Water Source

Identification of common ions in water is essential for the evaluation of beverage quality and utilization of water resources. However, most current approaches focus on the determination of water safety, and those for assessment of water quality are very rare. In this work, we took beer as an example and proposed an optical sensor array based on a series of supramolecular probes for the identification of six key brewing ions (KBIs) (Na⁺, Mg²⁺, Ca²⁺, HCO₃^-, SO₄^2-, and Cl^-) in brewing water. Six sensing units were designed and screened according to the different natures of each KBI, such as p<i>K</i>_a, electrified characteristics, coordination properties, etc. Spectroscopic studies indicated that KBIs could regulate the assembly and disassembly of supramolecular probes through noncovalent interactions (electrostatic, hydrophobic, π-π stacking, etc.), resulting in cross-reactive optical signals. In combination with linear discriminant analysis (LDA), a fingerprint database of brewing water quality was constructed for the first time with good accuracy, simplicity, and low cost simultaneously. Based on this database, different concentrations of single ions and their binary mixtures were distinguished with 100% identification accuracy. It can be further applied for rapid matching of water characteristics and beer styles and provides a strategy for precision brewing and targeted water resource development.