terclim by ICS banner
IVES 9 IVES Conference Series 9 PHOTOCHEMICAL DEGRADATION OF TRYPTOPHAN IN MODEL WINE: IMPACT OF HEAVY METALS AND OXYGEN ON 2-AMINOACETOPHENONE FORMATION

PHOTOCHEMICAL DEGRADATION OF TRYPTOPHAN IN MODEL WINE: IMPACT OF HEAVY METALS AND OXYGEN ON 2-AMINOACETOPHENONE FORMATION

Abstract

The wine industry worldwide faces more and more challenges due to climate change, such as increased dryness in some areas, water stress, sunburn and early harvesting during hot summer temperatures¹. One of the resulting problems for the wine quality might be a higher prevalence of the untypical aging off-flavor (ATA)². A substance, which Rapp and Versini made responsible for ATA, is the 2-aminoace-tophenone (2-AAP)³. 2-AAP in wine causes a naphthalene, wet towels, wet wool, acacia flower or just a soapy note⁴. The formation of the substance occurs via the degradation of tryptophan and the trypto-phan metabolite indole-3-acetic acid. The formation of 2-AAP is promoted by abiotic stress factors such as drought, low nitrogen content and high temperature, and by microorganisms via riboflavin, known as a photosensitizer5. In this study, the influence of other abiotic factors, namely oxygen and heavy me-tals, on the light-induced degradation of tryptophan to 2-AAP was investigated. Model wine with 0.53 µmol/l riboflavin was treated with UV-C light to stimulate tryptophan degradation. A linear increase in the intensity of UV-C light exposure caused a linear increase of 2-AAP. Increasing oxygen in the model wine supported the production of 2-AAP verifying that tryptophan degradation via riboflavin follows an oxidative pathway. Indeed, 2-AAP production decreased by 81 % when oxygen was reduced from saturation to anoxic conditions. It was also found that the presence of heavy metals led to a significant reduction of 2-AAP: 0.1 mmol/l Fe²+ decreased 2-AAP by 63 %, and 0.1 mmol/l Cu²+ decreased 2-AAP by 32 %. This observation can be explained by the Fenton reaction which requires Fe²+ and/or Cu²+ to produce – in this case – acetaldehyde from ethanol. It is suggested that the Fenton reaction acts as a competitive reaction to the photosensitized production of 2-AAP. As a lateral observation, the model wine in this study turned yellow after being UV-C radiated. The LC-MS signal suggested the substance lumichrome; its signal increased with the more yellow color of the model wine. Accordingly, riboflavin could not only act as a photosensitizer but also degrade itself after exposure to light.

 

1. Santos, J. A. et al. (2020). A Review of the Potential Climate Change Impacts and Adaptation Options for European Viticulture. Applied Sciences, 10(9), 3092. https://doi.org/10.3390/app10093092
2. van Leeuwen, C. et al. (2020). Recent advancements in understanding the terroir effect on aromas in grapes and wines. OENO One, 54(2). https://doi.org/10.20870/oeno-one.2020.54.4.3983 
3. Rapp, A., Versini, V., Ullemeyer, H. (1993). 2-aminoacetophenone: Causal component of ‘untypical aging flavour’ (‘naphthale-ne note’, ‘hybrid note’) of wine. Vitis, 32(1), 61-62. https://doi.org/10.5073/vitis.1993.32.61-62
4. Alpeza, I. et al. (2021). Atypical aging off-flavour and relation between sensory recognition and 2-aminoacetophenone in Croatian wines. Journal of Central European Agriculture, 22(2), 408-419. https://doi.org/10.5513/JCEA01/22.2.3103
5. Hühn, T. et al. (1999). Release of undesired aroma compound from plant hormones during alcoholic fermentation. Vitiv. Enol. Sci., 54, 105-113.

DOI:

Publication date: February 9, 2024

Issue: OENO Macrowine 2023

Type: Article

Authors

Svetlana Cvetkova¹, Sarah Edinger¹, Daniel Zimmermann¹ und Dominik Durner¹

1. Weincampus Neustadt/DLR Rheinpfalz, Institute for Viticulture and Enology, Breitenweg 71, D-67435 Neustadt an der Weinstraße, Germany

Contact the author*

Keywords

2-aminoacetophenone, iron, oxygen, riboflavin

Tags

IVES Conference Series | oeno macrowine 2023 | oeno-macrowine

Citation

Related articles…

RED WINE AGING THROUGH 1H-NMR METABOLOMICS

Premium red wines are often aged in oak barrel. This widespread winemaking process is used, among others, to provide roundness and complexity to the wine. The study of wine evolution during barrel aging is crucial to better ensure control of wine quality.
¹H-NMR has already been proved to be an efficient tool to monitor winemaking process [1]. Indeed, it is a non-destructive technique, it requires a small amount of sample and a short time of analysis, yet it provides clues about several chemical families.

Read More

PROFILING OF LIPIDS IN WINES FROM MONOCULTURE FERMENTATION WITH INDIGENOUS METSCHNIKOWIA YEAST SPECIES

Lipids are a diverse group of organic compounds essential for living systems. They are vital compounds for yeast which makes them an important modulator of yeast metabolism in alcoholic fermentation. This study presents a comprehensive lipidome analysis of wine samples from the Vitis vinifera L., Maraština. The fermentation trails were set up in monoculture with different indigenous yeast strains selected from a collection of native yeasts established at the Institute for Adriatic Crops and Karst Reclamation in 2021, previously isolated from Croatian Maraština grapes: Metschnikowia pulcherrima, Metshnikowia sinensis/shanxiensis , and Metschnikowia chyrsoperlae.

Read More

Rootstock mediated responses of grapevine (Vitis vinifera L.) metabolism and physiology to combined water deficit and salinity stress in Syrah grafts

Water deficit and salinity are increasingly affecting the viticulture and wine industry. These two stresses are intimately related; understanding the physiological and metabolic responses of grapevines to water deficit, salinity and combined stress is critical for developing strategies to mitigate the nega- tive impacts of these stresses on wine grape production. These strategies can include selecting more tolerant grapevine cultivars and graft combinations, improving irrigation management, and using soil amendments to reduce the effects of salinity. For this purpose, understanding the response of grape- vine metabolism to altered water balance and salinity is of pivotal importance.

Read More

ASSESSMENT OF ‘DOLCETTO’ GRAPES AND WINES FROM DIFFERENT AREAS OF OVADA DOCG

Dolcetto (Vitis vinifera L.) is one of the traditionally cultivated varieties in Piedmont (north-east Italy). Dolcetto wines have long been associated with local consumption and they are little known internationally. In particular, the Ovada area (south-east Piedmont), even if it represents a small share of the regional PDO Dolcetto production, is one of the oldest and vocated territory, giving wine also suitable for aging. In this study, the basic composition and phenolic content of Dolcetto grapes for Ovada DOCG wines have been investigated in three different vintages (2020-2022), as well as the main aspects of the derived commercial and experimental wines (basic parameters, phenolics, volatile compounds, sensory properties).

Read More

EFFECTS OF LEAF REMOVAL AT DIFFERENT BUNCHES PHENOLOGICAL STAGES ON FREE AND GLYCOCONJUGATE AROMAS OF SKINS AND PULPS OF TWO ITALIAN RED GRAPES

Canopy-management practices are applied in viticulture to improve berries composition and quality, having a great impact on primary and secondary grape metabolism. Among these techniques, cluster zone leaf removal (defoliation) is widely used to manage air circulation, temperature and light radiation of grape bunches and close environment. Since volatiles are quantitatively and qualitatively influenced by the degree of fruit ripeness, the level of solar exposure, and the thermal environment in which grapes ripen, leaf removal has been shown to affect volatile composition of grape berries [1].

Read More