Analysis of mousy off-flavour wines

Abstract

Winemakers are increasingly experimenting with new techniques, such as spontaneous fermentation, prolonged yeast contact, higher pH, minimal sulphur dioxid, filtration and clarification or oxidative ageing. Along with this, the risk of microbial spoilage increases, and so the off-flavour mousiness, long time underestimated, is becoming more frequent. Characteristic of the mousy off-flavour is the delayed perception after swallowing the wine. After a few seconds the flavour appears, reminiscent of a dirty mouse cage. There are three known compounds that cause mousy off-flavor: 2-ethyltetrahydropyridine, 2-acetyltetrahydopyridine, and 2-acetylpyrroline. Yeasts such as Dekkera/Brettanomyces and heterofermentative lactic acid bacteria like Lactobacillus hilgardii can release these compounds.

This study focuses on the analysis of mousy wines. This includes the quantitative analysis of mousy off-flavour compounds in wine using liquid chromatography with mass spectrometry (HPLC-MS). In order to identify the microorganisms in mousy wines, a next-generation sequencing analysis was carried out. Based on these results, a qPCR method will be developed to quantify the corresponding microorganisms in wine.