Use of the yeast Kluyveromyces marxianus for the innovation of wine productions and the improvement of their quality

Daniele Oliva, IRVO biologist

Between 2009 and 2012, IRVO isolated, identified and characterized yeast strains from grapes sampled on the small island of Linosa, where there are no wineries and therefore the possibility of contamination of the land by industrial strains is minimal. Using traditional microbiological methods, 3805 yeast colonies were isolated and then distinguished by molecular methods into 17 different species. 544 isolates were analyzed for key oenological characteristics such as fermentation vigor with and without sulfites, sugar consumption and alcohol production, volatile acidity, hydrogen sulfide, glycerol and beta-glucosidase. These analyses identified a strain of Kluyveromyces marxianus as the most interesting candidate for innovative wine production. Although this species was originally isolated from grapes and its enzymatic activities are used in enology, the yeast has rarely been used as a co-starter.

Between 2012 and 2016, K. marxianus strain Km L2009 was characterized and used in both laboratory-scale fermentations and experimental wineries. Strain Km L2009 showed growth ability even in the presence of 40 mg/L sulfites and 6% ethanol. Gas chromatographic analysis shows that wines produced by mixed fermentation with Saccharomyces cerevisae contain significantly higher amounts of free monoterpenes and aliphatic esters than wines produced only by commercial strains of Saccharomyces cerevisiae. The differences in the composition of volatile organic compounds resulted in sensory distinct wines. In light of these results, it is possible to state that even within the K. marxianus species it is possible to select strains capable of improving the aromatic quality of wines.

A new non-Saccharomyces yeast for the production of highly aromatic white and rosé wines.
The first strain of Kluyveromyces marxianus (Km L2009) for oenological use.

Diego De Filippi, HTS Enology

The present research work evaluated the feasibility of using under industrial conditions a non-Saccharomyces yeast strain belonging to a species not yet present in the oenological yeast market anywhere in the world: Kluyveromyces marxianus, named Km L2009.

The performance of this yeast strain, selected by IRVO on the island of Linosa in Sicily, had previously been evaluated in experimental-scale sequential fermentation and microvinification. The results revealed the potential of this strain for the production of intensely aromatic white wines. It was therefore decided to evaluate this propensity on white berry varieties (Grillo and Moscato) under real winemaking conditions managed both traditionally and with the use of automated fermentation management systems, also assessing the compatibility of the Km L2009 strain with different strains of S. cerevisiae.

In addition, the possibility of reproduction of the strain in question on an industrial scale was evaluated.
All wines obtained during the trials were evaluated through chemical-physical and sensory analyses, which showed that wines produced with the Km L2009 strain were the tasters’ favorites for aromatic intensity compared to wines produced with conventional commercial yeasts.