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…

EVALUATION OF INDIGENOUS SACCHAROMYCES CEREVISIAE ISOLATES FOR THEIR POTENTIAL USE AS FERMENTATION STARTERS IN ASSYRTIKO WINE

Assyrtiko is a rare ancient grape variety that constitutes one of the most popular in Greece. The objective of the current research was to evaluate indigenous Saccharomyces cerevisiae isolates as fermentation starters and also test the possible strain impact on volatile profile of Assyrtiko wine. 163 S. cerevisiae isolates, which were previously selected from spontaneous alcoholic fermentation, were identified at strain level by interdelta-PCR genomic fingerprinting. Yeasts strains were examined for their fermentative capacity in laboratory scale fermentation on pasteurized Assyrtiko grape must.

Read More

EFFECT OF WHOLE BUNCH VINIFICATION ON THE ABUNDANCE OF A SWEETENING COMPOUND

In classic red wine-making process, grapes are usually destemmed between harvest and the filling of the vat. However, some winemakers choose to let all or a part of the stems in contact with the juice during vatting, this is called whole bunch vinification. For instance, this practice is traditionally used in some French wine regions, notably in Burgundy, Beaujolais and the Rhone Valley. The choice to keep this part of the grape is likely to affect the sensory properties of wine, as its gustatory perception1,2.

Read More

HOW DOES ULTRASOUND TREATMENT AFFECT THE AGEING PROFILE OF AN ITALIAN RED WINE?

Many wine styles require moderate or extended ageing to ensure optimal consumer experience. However, few consumers have the interest or ability to age wine themselves, and holding wine in optimal conditions for extended periods is expensive for producers. A study was conducted on the use of ul-trasound energy on wine, with particular reference to its impact on sensory and chemical profiles. The OIV has authorised the use of ultrasound for processing crushed grapes (must) in Resolution OENO 616-2019, but not yet for finished wine1,2.

Read More

THE EFFECT OF COPPER ON THE PRODUCTION OF VARIETAL THIOLS DURING THE ALCOHOLIC FERMENTATION OF COLOMBARD AND GROS MANSENG GRAPE JUICES

Nowadays, the rapid growth of vineyards with organic practices and the use of copper as the only fun-gicide against downy mildew raises again the question of the effect of copper on varietal thiols in wine, especially 3-sulfanylhexan-1-ol (3SH) and its acetate (3SHA). A few decades ago, several works indicated that the use of copper in the vineyard had a negative effect on the content of varietal thiols in Sauvignon blanc wines [1, 2]. However, these studies only considered the concentration of the reduced form (RSH) of varietal thiols, without quantifying the oxidised ones. For this purpose, we proposed to monitor both reduced and oxidised forms of varietal thiols in wine under copper stress during alcoholic fermentation to have a more complete picture of the biological and chemical mechanisms.

Read More

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