Identification of Key Determinants for Perceived Sweetness and Sourness in Fresh Grapes

The perception of sweetness and sourness is a critical sensory indicator of the sensory quality of table grapes. This study comprehensively analyzed the relationships between traditional physicochemical evaluation metrics (soluble solids content, SSC; titratable acidity, TAC; and their ratio, RTT) and the perceived sweetness and perceived sourness assessed by a trained sensory panel across 42 grape varieties. Our findings reveal significant discrepancies between these traditional metrics and the perceived sweetness and sourness, indicating limitations in their accuracy for precisely characterizing the sensory experience. To achieve a more accurate description of grape perceived sweetness and sourness, we employed high-performance liquid chromatography and liquid chromatography-mass spectrometry to quantify the individual sugar and acid components within the grape juice from these 42 cultivars. Subsequently, we integrated correlation analysis and principal component analysis (PCA) for dimensionality reduction to conduct a comprehensive assessment of the sensory attributes. Ultimately, we identified tartaric acid and fructose contents as reliable key indicators for representing perceived sweetness and sourness, and the overall sensory quality of table grapes.