terclim by ICS banner
IVES 9 IVES Conference Series 9 INVESTIGATION INTO MOUSY OFF-FLAVOR IN WINE USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY WITH STIR BAR SORPTIVE EXTRACTION

INVESTIGATION INTO MOUSY OFF-FLAVOR IN WINE USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY WITH STIR BAR SORPTIVE EXTRACTION

Abstract

Mousy off-flavor is one of the defects of microbial origin in wine. It is described as a particularly unpleasant defect reminiscent of rodent urine (a “dirty mouse cage”), and grilled foods such as popcorn, rice, crackers, and bread crust. Prior to the 2010s, mousiness was very uncommon but it has been becoming more frequent in recent years. It is often associated with an increase in pH as well as certain oenological practices, which tend to significantly decrease the use of sulfur dioxide.

Three major compounds, 2-acetyl-1-pyrroline (APY), 2-acetyltetrahydropyridine (ATHP) and 2-ethyltetrahydropyridine (ETHP), have been identified as responsible for mousiness in wines. A particularity of these compounds is that they are prone to tautomerism and can coexist in several forms. Moreover, the nitrogen atom in the heterocyclic ring can be protonated under specific conditions, i.e. with pH lower than pKa, inducing a positive charge and, as a consequence, an increase of polarity and a loss of volatility of the molecule.

To date quantification data reported in the literature are limited due to analytical issues related to the nature of these compounds. To fill the gap and later understand the parameters influencing mousiness, the objective of this study was to develop a simple and effective method to simultaneously determine trace levels of these three mousy N-heterocycles in wines. Therefore, a stir bar sorptive extraction (SBSE) followed by GC-MS analysis was developed (1).

Firstly, both previously reported tautomers of ATHP (2), 2-acetyl-1,4,5,6-tetrahydropyridine and 2-acetyl-3,4,5,6-tetrahydropyridine were identified, unlike to APY and ETHP. The extraction conditions were then optimized paying particular attention to the pH of the sample. The performance of the developed method was evaluated on white, rosé and red wines and the limits of detection and quantification of the method are lower than previously published concentrations in spoiled wine.

The method was then applied to provide quantitative data by analyzing 6 control wines and 68 wines produced without added sulfites. ETHP was detected in almost all wines produced with limited use of SO₂. ATHP was detected in almost all wines suspected of mousiness whereas APY was only detected in few cases. This method will provide a support for further studies aimed at understanding the phenomena that influence the occurrence of mousy off-flavor and the oenological parameters that modulate its expression.

DOI:

Publication date: February 9, 2024

Issue: OENO Macrowine 2023

Type: Poster

Authors

Céline Franc¹, Daiki Kiyomichi², Pierre Moulis1,3, Laurent Riquier¹, Patricia Ballestra¹, Stéphanie Marchand¹, Sophie Tempère1 and Gilles de Revel¹

1. Univ. Bordeaux, INRAE, Bordeaux INP, Bordeaux Sciences Agro, UMR 1366, OENO, ISVV, F-33140 Villenave d’Ornon, France
2. Institute for Future Beverages, Kirin Holdings Company, Limited, 4-9-1 Jonan, Fujisawa, Kanagawa 251-0057, Japan
3. Department of Microbiology and Biochemistry, Hochschule Geisenheim University, Geisenheim, Germany

Contact the author*

Keywords

mousiness, N-heterocycles, quantification, SBSE-GC-MS

Tags

IVES Conference Series | oeno macrowine 2023 | oeno-macrowine

Citation

Related articles…

BIOSORPTION OF UNDESIRABLE COMPONENTS FROM WINE BY YEAST-DERIVED PRODUCTS

4-Ethylphenol (EP) in wine is associated with organoleptic defects such as barn and horse sweat odors. The origin of EP is the bioconversion reaction of p-coumaric acid (CA), naturally present in grapes and grape musts by contaminating yeasts of the genus Brettanomyces bruxellensis.
Yeast cell walls (YCW) have shown adsorption capacities for different compounds. They could be applied to wines in order to adsorb either CA and/or EP and thus reduce the organoleptic defects caused by the contaminating yeasts.

Read More

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

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.

Read More

CONTRIBUTION OF VOLATILE THIOLS TO THE AROMA OF RIESLING WINES FROM THREE REGIONS IN GERMANY AND FRANCE (RHEINGAU, MOSEL, AND ALSACE)

Riesling wines are appreciated for their diverse aromas, ranging from the fruity fresh characters in young vintages to the fragrant empyreumatic notes developed with aging. Wine tasters often refer to Riesling wines as prime examples showcasing terroir, with their typical aroma profiles reflecting the geographical provenance of the wine. However, the molecular basis of the distinctive aromas of these varietal wines from major Riesling producing regions in Europe have not been fully elucidated. In this study, new lights were shed on the chemical characterization and the sensory contribution of volatile thiols to Riesling wines from Rheingau, Mosel, and Alsace. First, Riesling wines (n = 46) from the three regions were collected and assessed for their aroma typicality by an expert panel.

Read More

‘TROPICAL’ POLYFUNCTIONAL THIOLS AND THEIR ROLE IN AUSTRALIAN RED WINES

Following anecdotal evidence of unwanted ‘tropical’ character in red wines resulting from vineyard interventions and a subsequent yeast trial observing higher ‘red fruit’ character correlated with higher thiol concentrations, the role of polyfunctional thiols in commercial Australian red wines was investigated.
First, trials into the known tropical thiol modulation technique of foliar applications of sulfur and urea were conducted in parallel on Chardonnay and Shiraz.1 The Chardonnay wines showed expected results with elevated concentrations of 3-sulfanylhexanol (3-SH) and 3-sulfanylhexyl acetate (3-SHA), whereas the Shiraz wines lacked 3-SHA. Furthermore, the Shiraz wines were described as ‘drain’ (known as ‘reductive’ aroma character) during sensory evaluation although they did not contain thiols traditionally associated with ‘reductive’ thiols (H2S, methanethiol etc.).

Read More

IDENTIFICATION OF NEW RESVERATROL DERIVATIVES FORMED IN RED WINE AND THEIR BIOLOGICAL PROPERTIES

Stilbenes are natural bioactive polyphenols produced by grapevine. Recently, we have reviewed the na- tural presence of these compounds in wines [1]. This study showed that the resveratrol and its glycoside, the piceid, are the most abundant stilbenes in wines. Resveratrol is a well-known stilbene with a wide range of biological activities. Due to its specific structure, resveratrol can be oxidized in wines to form various derivatives including oligomers [2]. In this study, we investigate the resveratrol and piceid transformation in wines.

Read More