Decoding Baijiu key sour compounds: Molecular distillation-enhanced enrichment and sensory-guided identification

Sourness, a critical yet systematically understudied taste component in Baijiu, primarily originates from organic acids, categorized into volatile and non-volatile types. Traditional flavor analysis methods are unsuitable for identifying the sour compounds. The low concentration of non-volatile acids poses challenges for enrichment and analysis. Therefore, a multi-stage molecular distillation technique was developed, achieving 78%-91.5% enrichment efficiency, combined with molecular sensory science to more effectively and scientifically analyze key sour compounds. A total of 56 acid compounds were identified. Through the taste dilution analysis (TDA) experiment, six acids with a higher taste dilution factor (TD) value (≥256) were identified: hexanoic acid, lactic acid, acetic acid, 3-methylbutanoic acid, 2-hydroxy-4-methylpentanoic acid, and butanoic acid. The taste activity values (TAV) values of hexanoic, lactic, and 3-methylbutanoic acid all exceeded 1. Further taste recombination and omission experiments confirmed that butanoic acid, lactic acid and acetic acid were the key contributors to sourness. • Molecular distillation was first employed to enrich acids in Baijiu; • 56 acids were identified, including 15 volatile acids and 41 non-volatile acids; • Key sour compounds of butanoic, lactic, and acetic acid were identified in Baijiu.