# New Insight on the Formation of 2-Aminoacetophenone in White Wines
###### Abstract  
This study aimed to improve the understanding of 2-aminoacetophenone (2-AAP) formation in white wines, a compound responsible for atypical ageing (ATA) associated with a rapid loss of white wine fruity aroma and to the development of unpleasant odors. Two surveys performed in 139 white wines from Central Europe investigated the varietal effect on wine tendency to form 2-AAP during ageing. The role of some antioxidants and important transition metal ions present in wine (Fe, Cu and Mn) in the formation of 2-AAP was also investigated. The surveys highlighted that Muscat and Riesling wines showed significantly higher concentrations of 2-AAP than Chardonnay and some other regional varieties found in Central Europe such as Grunner Veltliner, Welschriesling and Zelen. The origin of such varietal effects could not be related to the level of any 2-AAP precursor. On the other hand, some of the important wine matrix effects were highlighted. A certain variability in capacity of different antioxidants to limit 2-AAP formation was observed. Supplementations of commercial tannins in wines tended to be more efficient than glutathione in preserving wines from the formation of 2-AAP. Transition metal ions significantly impacted 2-AAP synthesis through complex interactions. Generally, Fe and Mn tended to promote formation of 2-AAP, while the presence of Cu limited it. The higher concentration of transition metal ions significantly improved the efficiency of antioxidants to reduce 2-AAP formation. Further studies investigating the origin of varietal effects and the complex matrix effects involving metal ions and antioxidants in 2-AAP production are warranted. 2-aminoacetophenone; transition metal ions; antioxidants; atypical ageing 2023  
White Wines 2023  
[PERSON], [PERSON] V  
cleavage of 3-IAA by superoxide radicals, produced by the aerobic oxidation of sulfite during storage of sulfurized wines, form 3-(2-formylaminophenyl)-3-oxopropinoic acid (FAPOP). The decarboxylation of FAPOP leads afterwards to the formation of N-formyl-2-aminoacetophenone (FAP) and finally to 2-AAP, or alternatively, oxidized indole-acetic acid. The possibility that other metabolites such as tryptophan, indole-3-lactic acid (ILA) and kynure could be co-oxidized to 2-AAP after sulfite addition was also investigated, but these reactions only had a minor contribution to the formation of 2-AAP in wine [4]. The photooxidation of free and protein-bound tryptophan in combination with storage conditions could also potentially yield 2-AAP [6]. On the other hand, 2-AAP could be formed by yeasts during alcoholic fermentation, but again in concentrations below the sensory threshold [7,8]. While the chemical reactions yielding 2-AAP concentrations in white wines have been well described, the factors driving its formation in wines are still poorly understood [2]. The high levels of free 3-IAA at sulfiting increases the risk of obtaining higher levels of 2-AAP later in the wine, but no close correlation was established between the concentrations of 3-IAA and 2-AAP in wines [2]. The formation of 2-AAP requires only some residual traces of dissolved oxygen, which are incapable of leading to classical oxidative ageing. However, the presence of antioxidants before sulfiting was reported to prevent the formation of 2-AAP [4,9]. It has been shown that the addition of ascorbic acid could strongly inhibit the formation of 2-AAP [10]. However, the use of ascorbic acid in winemaking can promote the formation of strong oxidants if at the same time the level of sulfur dioxide is too low [11]. Consequently, research has been carried out to find an alternative to ascorbic acid in order to prevent the formation of 2-AAP in wine. Among other antioxidants used in oenology, the effect of tannin and glutathione supplementation in wine did not consistently limit the 2-AAP formation [2]. In contrast, [PERSON] et al.