Expertise documents

Hydrogen sulphide (rotten egg) aroma is a serious fault in wine and will result in quality loss in the final product. Its production is mainly found during alcoholic fermentation. H2S production by wine yeast varies based on the yeast used as well as on the environmental factors, especially the assimilable nitrogen concentration and micronutriens present. Ranging from low to high producers, this characteristic is important to take into account, as well as the nutritional status of the must, when deciding on a fermentation strategy. The best way to avoid formation of H2S during winemaking are to choose a low H2S yeast producer and apply good fermentation practices, and also use wine yeast such as Lalvin Sensy™ which have been especially selected to avoid the production of this compound while keeping in mind a good nutrition and oxygen addition strategy. It is adapted to white winemaking fermentation where the conditions (such as low NTU, low temperature, low YAN) could affect H2S formation, and the Lalvin Sensy™ with its low capacity to produce H2S, as well as SO2 and acetaldehyde, will let the varietal aromas be fully expressed. WE #7 - Sigrid

Wine yeast requires certain essential elements to transform must into wine: sugars, vitamins and minerals, some oxygen, and also very importantly, a sufficient concentration of Yeast Asssimilable Nitrogen. This type of nitrogen (YAN) is composed of amino acids, some small peptides and ammonium that can be used by yeast cells to not only complete fermentation, but also to fully develop the sensory profile of the wine. Many wine musts are deficient in nitrogen and the type of nutrient used and the timing of additi on is crucial in the development of AF. WE#8 ENG

The tendency to harvest higher maturity grapes, resulting in higher pH and alcohol wines, seems more favorable to the development of indigenous bacteria. To limit the development of unknown indigenous flora, which can lead to the production of undesirable sensory deviations, co-inoculation is an interesting winemaking option and using selected Lb. plantarum in the freeze-dried form for direct inoculation appears to be a very safe winemaking option in combination with the co-inoculation strategy. L. plantarum ML Prime™ offers several advantages: good implantation, fast, effective dominance in co-inoculation and very fast, complete MLF under high pH conditions. In addition, its facultative heterofermentative characteristics makes ML Prime™ a safe choice for preventing the formation of acetic acid (volatile acidity) from hexose sugars. For more information on this topic, WUP #1-2015 ML Prime - SK  

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Proceeding of the XXIVes Entretiens Scientifiques Lallemand - 'Understanding Varietal Aromas During Alcoholic and Malolactic Fermetnations'.  This booklet includes a presentation by  Dr Matthew Goddard, School of Biological Sciences, University of Auckland, New Zealand titled 'Merging Ecology of Wine Microbiology" Download PDF