Investigating Abiotic Stress-Induced Off-Flavor in Different White Wine Varieties (Vitis vinifera L.) Using a Complementary Approach of Sensory Analysis and Nontargeted Gas Chromatography Mass Spectrometry Analysis

To better understand the sensory changes of white wines from abiotic stressed vineyards affected by climate change, we conducted a survey with 106 volunteers working in the German wine industry. The results of this survey allow us to infer that in recent years, the atypical aging (ATA) note became rather an umbrella term used by German wine professionals to describe low-quality wines made from vineyards suffering from abiotic stress. This broad use of the term indicates that it is no longer strictly associated with 2-aminoacetophenone (2-AAP), a compound known for producing an aroma reminiscent of acacia blossoms and mothballs. To further explore the sensory characteristics and chemical origin of the so-called ATA note in white wine, we conducted descriptive analysis, nontargeted HS-SPME-GC-MS, and targeted 2-AAP analysis on a set of 38 authentic white wines, including rejected wines due to ATA and their accepted counterparts from the official PDO (protected designation of origin) examination in Germany. Although 2-AAP has often been cited as the primary contributor to the ATA off-flavor, our results show that none of the rejected wines exceeded the published odor threshold for this compound. The rejected wines, however, had significantly higher concentrations of higher alcohols and branched-chain fatty acids, along with significantly lower concentrations of fruity esters than their accepted counterparts. In light of these findings, we recommend using the term "abiotic stress note" as an umbrella term for the general negative aroma associated with wines made from low-quality grapes grown in vineyards experiencing abiotic stress.