Eun-Ha Chang

Changes of volatile compounds in vitis labrusca ‘Doonuri’ grapes during stages of fruit development and in wine

This study was investigated to elucidate the changes in volatile compounds of grapes of the ‘Doonuri’ that occurred during the ripening and that found in wine made from these grapes. Volatile compounds were extracted by simultaneous steam distillation and were subjected to gas chromatography–mass spectrometry. Ten alcohols, 8 aldehydes, 14 esters, 7 ketones and lactones, and 3 other odor-active compounds were identified in grapes during ripening of berries and in wine. Alcohol compounds were detected at high concentrations than other compounds in wine. The concentrations of aldehydes were highest at initial stage of berry development, but was not detectable in wine. Ester, ketone, and lactone compounds were appeared primarily after veraison and were consistently increased till harvest period. Ester, ketone, and lactone compounds in wine had higher odor activity values than other compounds. The flavor of the ‘Doonuri’ grapes and wine was primarily developed from ester, ketone, and lactone compounds and unusual aroma like slightly dried peppery and tobacco leaf.

Changes in the aromatic composition of grape cv. Cheongsoo wine depending on the degree of grape ripening

The volatile composition and properties of wine made using the ‘Cheongsoo’ grape cultivar harvested at different stages of ripening were evaluated. There were changes in the chemical composition of ‘Cheongsoo’ wine, including pH, total acidity, total polyphenols, and tannins according to the degree of grape ripening. Colorimetric analysis indicated that wines had yellow tones and deep and very strong colors with a high chromatic intensity depending on the degree of grape ripening. Of 87 detected flavor compounds, 26 had high OAV (odor active values). Based on OAV, 26 compounds were considered to be important odorants for ‘Cheongsoo’ wine. A harvest date of September 19 showed good separation from August 29 and September 8 and 29, depending on the degree of grape ripening, on a principle components analysis plot for grape ripening. More volatile compounds were present in September 19 harvested grapes.