Physicochemical properties, antioxidant activities and sensory characteristics of commercial gape vinegars during long-term storage

This study was designed to investigate changes in quality characteristics during long-term storage of five commercial grape vinegars (V1 similar to V5). To determine long-term quality characteristics of vinegars, proximate (soluble solid, pH, total acidity, color, and antioxidant activity) and sensory descriptive analysis, were performed. Initial soluble solids were high in V4 and V5 (contained higher liquid fructose or grape concentrate), but after 12 mo of storage, soluble solids decreased significantly in V4 and V5 (non-sterile products). Initial total acidity was close to the amount of additional juice, while V4 and V5 had increased total acidity after 12-mo storage. Browning was dominant in V4 and V5 regardless of storage periods. Initial DPPH radical scavenging activity was high for all samples, while it tended to decrease after 6-mo storage. In sensory descriptive analysis, browning and turbidity was markedly elevated during 12-mo storage in general. Aromatic factors were significantly attenuated in all test samples during storage. Interestingly, V4 and V5 were considered as having lower sourness and bitterness since sweetness was stronger in these than in other samples due to the addition of liquid fructose. The results suggest that for optimal quality, commercial grape vinegars are best consumed within 6 mo of storage after opening.