Effect of Indigenous Non-Saccharomyces Yeasts on Lipid Compositions of Maraština Wine

This study is the first to investigate the impact of indigenous non-Saccharomyces yeasts, including Hypopichia pseudoburtonii, Metschnikowia sinensis/shanxiensis, Metschnikowia chrysoperlae, Metschnikowia pulcherrima, Lachancea thermotolerans, Hanseniaspora uvarum, Hanseniaspora guilliermondii, Hanseniaspora pseudoguilliermondii, Pichia kluyveri, and Starmerella apicola on the lipid composition of sterile Maraština grape juice and wines using the UHPLC-MS/MS method. Yeasts were tested in monoculture and sequential fermentations alongside commercial Saccharomyces cerevisiae. Indigenous non-Saccharomyces yeasts showed the potential to improve fermentation performance and enable the development of new wine styles through the biosynthesis of an unsaturated fatty acid pathway, which was identified as the most significant pathway. In monoculture fermentations, L. thermotolerans, H. uvarum, H. guilliermondii, H. pseudoguilliermondii, and P. kluyveri significantly reduced lignoceric acid, potentially influencing wine aroma through the formation of esters and higher alcohols. Hyp. pseudoburtonii, M. chrysoperlae, M. pulcherrima, P. kluyveri, and S. apicola increased the demand for lipids, such as stearic acid, which may help preserve membrane permeability by integrating into the membrane in response to ethanol shock. The most significant impact on free fatty esters was observed in fermentations with H. pseudoguilliermondii. Furthermore, L. thermotolerans in sequential fermentations significantly reduced arachidic, stearic, and palmitic acid. P. kluyveri reduced the content of erucic and linoleic acid.

Medium chain fatty acids and fatty acid esters as potential markers of alcoholic fermentation of white wines

Aroma components of wines play an important role in the sensory quality of wines. In our paper we investigate the effect of commercially available yeast nutrients under different fermentation parameters. Caproic acid, caprylic acid, capric acid, and different fatty acid esters were used as markers of the alcoholic fermentation process. The optimal temperature for the fermentation of different white wines was at 15–16 °C, in the case of examined wines lower concentrations of fatty acids and fatty acid esters were found at this temperature. At 25–26 °C fermentation temperature very high concentrations of fatty acids and fatty acid esters were detected. Applying different nitrogen-containing wine additives we managed to achieve better aroma profiles for white wines even using musts of lower quality.

Comparison of MCFA and Other Methods of Terminating Alcohol Fermentation and Their Influence on the Content of Carbonyl Compounds in Wine

This study deals with the effects of the use of a mixture of medium-chain fatty acids (MCFA) at the end of the alcohol fermentation process on the content of carbonyl compounds in wine. During the experiment, the effects of the addition of MCFA at doses of 10 and 20 mg/L were compared to the termination of alcohol fermentation using cross-flow filtration and chilling treatments. Individual carbonyl compounds were determined by HPLC analysis. The experiment showed that the addition of MCFA caused a reduction of the acetaldehyde content compared to the chilling process, and a reduction of the diacetyl content compared to cross-flow filtration. Throughout the experiment, a lower level of total carbonyl compounds was observed after the addition of MCFA.

Influence of medium chain fatty acids on some botrytised wine-related yeast species and on spontaneous refermentation of Tokaj essence

Medium chain fatty acids are candidates of partial sulphur dioxide replacement in wine, as a solution to the growing consumer concerns about chemical additives. In botrytised sweet wine specialties, large amount of sulphur dioxide addition is one of the effective practices to stop alcoholic fermentation. Increasing medium chain fatty acid levels up to 80 mg l-1 was tested as a sole inhibitor on solid agar surface. S. bacillaris seemed to be the most sensitive, S. cerevsisiae and S. bayanus were more tolerant, while Z. bailii showed the highest tolerance. Then, increasing medium chain fatty acid levels up to 40 mg l-1 combined with 100 mg l-1 sulphur dioxide was introduced into a Tokaj Essence under refermentation. After 56 days, the highest dosage had pronounced effect on the yeast population, but the refermentation was not inhibited completely. Medium chain fatty acids have varying inhibitory effect on botrytised wine-related yeasts, moreover, it could be used effectively in media with high ethanol content, unlike Tokaj Essence.