A simple and efficient strategy for visible aldehydes and ketones detection and its application in baijiu grade discrimination.

A novel colorimetric sensor array using hydroxylamine hydrochloride salts (HAs) and dyes enables rapid detection of aldehydes and ketones (AKs) detection for baijiu quality assessment. Overcoming traditional limitations of time-consuming and complex material synthesis, this work leverages AKs' electrophilicity through nucleophilic reactions with hydroxylamine that release HCl and induce color changes of the indicator. The electrophilicity of AKs is the critical factor in generating distinct fingerprint color patterns. Density functional theory calculations of local electron attachment energy revealed the mechanism behind distinct color patterns observed in 20 AKs. A particle swarm optimization algorithm combined with variable-weighted partial least squares support vector machine was introduced to quantify 3-hydroxy-2-butanone and acetal in mixed compounds. Applied to 27 strong-aroma baijius, the array achieved 4-min discrimination with high accuracy. This technology demonstrates significant potential for rapid quality evaluation in alcoholic beverages, combining theoretical insights with practical analytical capabilities while eliminating complex material synthesis requirements.