Lipid-derived bitter compounds in sturgeon caviar: Metabolomic identification and sensory validation

Bitterness is an unexpected sensory defect in certain sturgeon caviar products, reducing consumer acceptance and market value. To investigate its chemical and sensory basis, this study combined untargeted metabolomics, molecular dynamics simulations, and multi-modal sensory evaluations. A total of 406 differential metabolites were identified, primarily associated with lipid metabolic pathways. Cucurbitacin D (3.97 μg/g), ricinoleic acid (312.83 μg/g), and ethyl hexadecanoate (73.35 μg/g) were elevated in bitter caviar and showed strong hydrophobic binding to the TAS2R46 receptor. Sensory evaluation and electronic-tongue analysis confirmed their bitterness. The sensory thresholds of ricinoleic acid and ethyl hexadecanoate were 30.715 and 4.969 mg/L, respectively. Taste activity values (TAVs) indicated ethyl hexadecanoate (TAV = 14.76) as the dominant contributor to perceived bitterness. Taste reconstitution experiments validated the sensory effects of these compounds. These findings provide mechanistic insight into lipid-derived bitterness in caviar and establish a foundation for improving its sensory quality control.