Effect of storage at elevated temperatures on aroma of Chardonnay wines

The effect of elevated temperatures during storage on wine aroma was determined for commercial Chardonnay wines with and without oak aging. A significant difference in aroma was detected between the control wine (held at 5 degrees C) and the unoaked (94-U) and oaked (94-O) 1994 wines, after they were held at 40 degrees C for five and seven days, respectively. The 1993 oak-aged wine (93-O) was more resistant to the storage treatment, with a significant difference produced only after nine days at 40 degrees C. After five to nine days of heated storage, only Very small decreases in glycosyl glucose (GG) level were observed, suggesting that the initial changes affecting aroma were not a result. of hydrolysis of glycosides. To characterize the changes in aroma produced by heating, wines stored at 40 degrees C for 0, 15, 30, and 45 days were profiled by descriptive analysis using trained judges. Upon heating of all wines (93-O, 94-O, 94-U), the intensity of floral and fruity notes decreased, while aromas associated with oak and aging increased: honey, butter/vanilla, oak, tea/tobacco and rubber. The first 15 days of heating resulted in significant increases in the honey, rubber and tea/tobacco attributes and decreases in citrus, tropical fruit, green apple and floral aromas. Increasing the storage time to 30 days resulted in a further decrease in fruity aromas and increase in honey, rubber, tea/tobacco, butter/vanilla, and oak. Few further changes in aroma occurred when storage was extended to 45 days. Although larger decreases in GG concentration occurred upon heating for 15 to 45 days, no consistent relation between GG and the attributes was found.