Assessment of Sour Taste Quality and Its Relationship with Chemical Parameters in White Wine: A Case of Koshu Wine

This study aimed to clarify the sensory characteristics of Koshu wine, which is the most popular white wine produced in Japan, by identifying descriptive terms for sour taste, a primary aspect of wine flavor. A sensory evaluation generated 56 terms related to sour taste quality. Some terms were categorized on the basis of the timing of perception— immediately after sipping, holding in the mouth, and after swallowing—while others were classified as expressing “temporal change”, “overall impression terms”, or “metaphorical terms”. From these, 12 terms—“fresh”, “stand out”, “sharp”, “soft”, “round”, “gentle”, “bright”, “duration”, “crisp”, “intensity”, “mild”, and “calm”—were selected, with definitions and reference standards (materials or examples that represent each characteristic) established. A trained sensory panel evaluated 16 Koshu wines, revealing significant differences in all sour taste quality terms except “duration”. The evaluation of “duration” may require improvement. Correlation analysis indicated that pH was strongly associated with “sharp” sour taste immediately after sipping, while titratable acidity and pH correlated with “round” and “gentle” sour taste when the wine was held in the mouth. Total acidity was linked to the duration of sour taste. Applying the sour taste quality terms determined from this study will enable the quantification of the sour taste quality of wines.