Quantification of newly identified C8 aroma compounds in musts and wines as an analytical tool for the early detection of Fresh Mushroom Off-Flavor

Abstract

The Fresh Mushroom Off-Flavor (FMOff) is a concerning undesirable aroma in wine specific of certain vintages, characterized by a typical button mushroom aroma. The appearance of this off-flavor is linked to the presence of certain fungus on the grape [1-3]. One of the main problems of the defect is that it is not sensory perceived in the musts and appears only at the end of alcoholic fermentation [4]. Consequently, the use of must with potential FMOff in blending can lead to the spoilage of large amount of wine.

Today, fresh mushroom aroma compounds are well documented: they are saturated and unsaturated C7, C8 and C9 compounds, the most common and sought-after compounds being 8 carbon-compounds, such as 1-octen-3-ol, 3-octanone,or1-octen-3-one [2, 5, 6] and more recently, 1-hydroxyoctan-3-one [7]. However, these compounds can be difficult to measure notably in the case of 1-octen-3-one and do not fully explain this defect appearance during winemaking. The aim of this work was to identify reliable FMOff compounds in both musts and wines and to propose a high-throughput analytical method to discriminate samples of different quality as early as possible.

First, experimental altered musts were made from grapes with a natural apparent alteration by grey mold. Untargeted GC-MS analysis of the musts allowed to identified two compounds correlating well with the development of FMOff in the wines: 1-hydroxyoctan-3-one and octane-1,3-diol, the latter being identified for the first time in an oenological sample. Their concentrations, measured using a rapid analytical method developed by SIDA-LC-MS/MS, ranged from some µg/L to mg/L with a clear correlation with the FMOff intensity (sensory perception) (R² = 0.95 and ² = 0.89, respectively).

Then, 82 samples (62 base wines and 20 musts used to make these wines) were collected in the Champagne region during the 2023’s harvest. Based on sensory analysis results, 33 wines developed a FMOff and 29 were considered as control samples (no FMOff detected). Both 1-hydroxyoctan-3-one and octane-1,3-diol were quantified in these samples. The quantification of both compounds allowed a clear discrimination of FMOff wines from control samples (p<0.0001), confirming the reliability of 1-hydroxyoctan-3-one and octane-1,3-diol as FMOff markers in base wines. More interestingly, 1-hydroxyoctan-3-one was quantified in 90% of the musts giving a wine with a FMOff character. Octane-1,3-diol was quantifiable in 100 % of the musts from the FMOff group and detected at lower concentrations in the control musts. Thus, the quantification of these two markers in the musts allowed the identification of future wines with FMOff potential, thus providing a rapid and reliable tool to segment the quality of must before fermentation.

References

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