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…

Overhead spray water treatment as a mitigation strategy for reducing vine stress and preserving grape quality during heatwaves

Changes in climate have been influencing the quality of wine grapes worldwide. The impact of extreme climate events over short periods is increasingly recognized as a serious risk to grape quality and yield quantity. In this study the mitigation effects of a pulsed water spray on vine canopy during heatwave events has been evaluated for maintaining vine condition during the growing season and grape quality. Vines of three varieties (Malbec, Bonarda, and Syrah) under drip irrigation in the UNCuyo experimental vineyard were treated with an overhead pulsed water spray.

Read More

IMPACT OF CLIMATIC ZONES ON THE AROMATIC PROFILE OF CORVINA WINES IN THE VALPOLICELLA REGION

In Italy, in the past two decades, the rate of temperature increases (0.0369 °C per year) was slightly higher compared to the world average (0.0313 °C per year). It has also been indicated that the number and intensity of heat waves have increased considerably in the last decades. (IEA, 2022). Viticultural zones can be classified with climatic indexes. Huglin’s index (HI) considers the temperature in a definite area and has been considered as reliable to evaluate the thermal suitability for winegrape production (Zhang et al., 2023).

Read More

Influence of agrophotovoltaic on vine and must in a cool climate

The current energy crisis means that interest in agrophotovoltaics has increased significantly. The reason behind this is that the system aims to combine agricultural production with energy production. During the three-year period from 2020 to 2022, the effects of photovoltaic panels on the vine, the yield and the quality of the must were studied in Walenstadt in northern Switzerland, an area with a cool, humid climate. 65 Pinot noir vines were planted in the 160m2 study area. Because of the large edge effects, only 3 repetitions with 4 vines each could be created. A significantly lower leaf infestation by Plasmopara viticola was observed among the panels in each of the three years.

Read More

MOVING FROM SULFITES TO BIOPROTECTION: WHICH IMPACT ON CHARDONNAY WINE?

Over the last few years, several tools have been developed to reduce the quantity of sulfites used during winemaking, including bioprotection. Although its effectiveness in preventing the development of spoilage microorganisms has been proven, few data are available on the impact of sulfite substitution by bioprotection on the final product. The objective of this study was therefore to characterize Chardonnay wines with the addition of sulfite or bioprotection in the pre-fermentation stage. The effects of both treatments on resulting matrices was evaluated at several scales: analysis of classical oenological parameters, antioxidant capacity, phenolic compounds, non-volatile metabolome and sensory profile.

Read More

WINE LEES AS A SOURCE OF NITROGEN FOR OENOCOCCUS OENI TO IMPROVE MALOLACTIC FERMENTATION PERFORMANCE

Malolactic fermentation (MLF) is a desired process in red and acidic white wines, after alcoholic fermentation (AF), carried out by the lactic acid bacterium (LAB) Oenococcus oeni. The advantages are an increase of pH, microbiological stabilization and organoleptic improvement of the final wine. However, the presence of stress factors such as ethanol, low pH, high total SO2, lack of nutrients and presence of inhibitors, could affect the successful completion of MLF [1]. Changes in amino acid composition and deficiencies in peptides after AF, showed that MLF can be delayed, signaling its importance for bacterial growth and L-malic acid degradation during MLF [2].

Read More