The purpose of this study was to investigate the quality characteristics and volatile flavor components of Doonuri wine, using freeze concentration. The freeze concentration can increase the sugar concentration in grape juice by reducing its water content. In this study, after eight days od fermentation, the alcohol content of freeze-concentrated Doonuri wines was 12.5~14.1%. The pH of the wine was 3.42~3.50 and the total acid content was 0.68~0.94 g/100 mL, respectively. The brghtness of freeze-concentrated Doonuri wines was 19.28~54.42, the redness was 41.98~49.58, and the yellowness was 36.16~42.36. The organic acid analysis of Doonuri wines was that most of the organic acids contain tartaric and malic acid. By using freeze concentration with grape juice, significant increase in the total polyphenol content of Doonuri wines was 122.40~137.26 mg/mL, the total anthocyanin content was 117.06~ 118.40 mg/L and the tannic acid content was 66.23~83.70 mg%. In GC/MS analysis, the volatile flavor component analysis of Doonuri wines identified six alcohols, five esters, two ketones, on acid, two alkanes, and four other compounds.

This study was conducted to investigate several indicators of fruit maturity, and expert sensory evaluation was done to determine the most appropriate maturity time for the new Korea grape cultivar ‘doonuri’ for high quality winemaking. The grape component changed dramatically during ripening, after veraison. Considerable drops in berry firmness (<0.60 kgf/cm2) and titratable acidity (<0.66%) were found at the ripening stage while the soluble solid content significantly increased in the ripening process. Most of the organic acids contained were tartaric and malic acid. The malic acid content was about twice the tartaric acid content in the fruit-growing period but was less than the tartaric acid content in the maturity period. The total anthocyanin and polyphenol contents increased sharply after veraison. In particular, the total anthocyanin and polyphenol contents reached their maximum levels when the acidity was 0.55%, and after that, there was almost no change. Correlations between anthocyanin accumulation and several factors were found in sugar 0.7811 (p<0.05), pH 0.9315 (p<0.05), and Brix/acid ratio 0.9409 (p<0.05). Brix×pH2 and brix/acid ratio were used as indicators of the proper maturation of the grapes when the acidity was 0.53 to 0.55%, and at sugar 17 Brix. When surveyed, the quality characteristics and sensory evaluation of the wine made using the latest harvested grapes showed the most reliable sourness. The color, aroma, and overall harmony of the wine, however, were evaluated to be the best when the wine acidity was about 0.60% or when the grape acidity was below 0.55%.