Impact of Rootstock, Clonal Selection, and Berry Size of Vitis vinifera sp. Riesling on the Formation of TDN, Vitispiranes, and Other Volatile Compounds

Abstract

The C13-norisoprenoid aroma compounds 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) and biosynthetically related vitispirane (VS) are important contributors to the varietal aroma of Riesling wines and are released from glycosidically bound carotenoid breakdown products during bottle aging. TDN is appreciated by numerous winemakers, particularly in aged Riesling wines. Higher levels of TDN, however, are perceived as a “petrol” off-flavor, which is expected to increase due to ongoing climate change. Wines produced from the same Riesling clone, which was grafted on six different rootstocks, varied significantly throughout two vintages in respect to their concentrations of free and bound TDN and VS as well as other volatiles. Over three vintages, the same compounds differed significantly among wines made from eight Riesling clones grafted on the same rootstock. Genetically determined loose grape clusters favored the formation of TDN and yielded wines of stronger sensory petrol intensity. Berry size, however, had no relevant impact on TDN and VS formation.

The Effect of Elevated CO2 on Berry Development and Bunch Structure of Vitis vinifera L. cvs. Riesling and Cabernet Sauvignon

“…As vinification from smaller berries supposedly results in higher quality wines due to a higher concentration of compounds located in the grape skin such as flavonols or anthocyanins [14], it is advisable to investigate if the higher single berry weights derived from eCO 2 treatment might have a negative effect on the amount of grape skin compounds in both cultivars. Additionally, the variation in berry size among Riesling clones is reported not to be responsible for different levels of C 13 -norisoprenoid aroma compounds like 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) [21], well known to produce petrol-like off-flavors in Riesling wine [62]. Therefore, it could be of interest to study the impact of different CO 2 environments on TDN concentration in Riesling.…”

“…Nevertheless, all studies conducted on field-grown grapevines under eCO 2 conditions embraced that there is no positive or negative repercussion of eCO 2 on grape or wine quality [2,3,7]. On the other hand, eCO 2 was shown to affect grapevine vigor and growth, especially bunch and berry weight or berry number [3,6,9], and it could, therefore, lead to quality changes by altered berry sizes [14][15][16][17][18][19][20][21].…”

“…Sangiovese. However, berry size was discussed to be related to berry and wine quality [14][15][16][17][18][19][20][21]. Hence, the quality of grapes grown under eCO 2 might be affected.In other perennial fruit crops like pears and sour oranges, enhanced fruit weight, volume, and diameter were detected under eCO 2 [22][23][24].…”

“…Sangiovese. However, berry size was discussed to be related to berry and wine quality [14][15][16][17][18][19][20][21]. Hence, the quality of grapes grown under eCO 2 might be affected.…”

Recent advancements in understanding the terroir effect on aromas in grapes and wines

“…in warm locations express more tropical fruit aromas and less asparagus and boxwood aromas. Riesling produced in warm climates is more prone to express kerosene-like and ripe fruit flavours induced by the presence of TDN and rearrangement of linalool towards oxide forms or α-terpineol (Marais et al, 1992;Ziegler et al, 2020).…”