Wednesday May 19
The development of a powerful antioxidant to protect musts in the pre-fermentation phases
Sieczkowski Nathalie, Lallemand Oenology
White and rosé winemaking requires particular attention to the risks associated with oxidation phenomena. Color and aroma are key determinants of wine quality and freshness so oxidative stability is at the heart of winemakers’ concerns, especially given the current trend to limit chemical inputs, particularly sulfites.
In this context, research is leading to a better understanding of wine oxidation mechanisms leading to the development of new tools aimed at improving the longevity of wines during aging and storage in the cellar and beyond after bottling.
In this talk, we present the research work carried out in collaboration with the IUVV in Dijon, which highlights the impact of a new specific inactivated yeast developed for the protection of musts and wines against oxidation.
The new specific inactivated yeast Glutastar™ results from the application of an optimized production process to a unique strain of Saccharomyces cerevisiae yeast selected to maximize the biosynthesis and accumulation of intracellular glutathione and other compounds of interest.
Non-targeted metabolomic characterization has demonstrated the unique composition of the new inactivated yeast and its impact on wine compared with other inactivated yeasts. In addition to its high content in reduced glutathione, the presence of other nucleophilic peptides further increases the positive impact of this specific inactivated yeast on the oxidative stability of wine.
Numerous application trials have been carried out on white and rosé vinifications and the results show that early treatment before fermentation (after pressing, during clarification or in pre-fermentation maceration) with the specific inactivated yeast allows for better preservation of aromatic compounds and color beyond bottling.
Bioprotection with an innovative Metschnikowia able to consume oxygen
Gerbaux Vincent, IFV Institut Français de la Vigne et du Vin
The pre-fermentation phase, especially in white and rose wine, includes oenological operations that promote oxidation phenomena and the development of contaminating microorganisms.
The traditional use of SO2 may reduce these problems, but the current trend is to minimize dosage, or even eliminate it. The risk of losing control of the pre-fermentation phase becomes more and more possible.
Why not consider bioprotection with the flora of non-fermentative yeasts as an alternative and innovative solution? The IFV has selected the Metschnikowia pulcherrima LCH15.21 (Level2 InitiaTM) strain from a collection of over 500 yeast strains isolated from grapes and musts. This yeast is able to colonize the must without fermenting or producing undesirable compounds. The inoculation can be carried out at the time of crushing or during the mechanical harvest.
In several comparative tests monitoring dissolved oxygen of pasteurized white musts incubated at 12 ° C, results in a similar increase between the control wines and those with sulphite added at 50 mg/L. They reach a dissolved oxygen plateau of 9 and 8 mg / L respectively. In the case of using Metschnikowia LCH15.21 as bioprotection, a high consumption of dissolved oxygen was observed, reaching insignificant levels in a few hours. Unwanted oxidative, enzymatic and microbiological phenomena are then inhibited. Through further practical experiences, José Maria Heras will illustrate the dominant effect on indigenous flora, the effectiveness on copper reduction and the consequent positive effects of yeast on the quality of wine.
This new possibility of bioprotection allows greater freedom in the management of the pre-fermentation phase, also favoring good aromatic expression. The use of this specific yeast during cold sedimentation can represent a significant technical advantage.
Preserve freshness and longevity during post alcoholic fermentation phases
José‐Maria Heras, Lallemand Oenology
Once fermentations are finished, and before bottling, wine is vulnerable to oxidation. The oxygen ingress can vary depending on the operation. SO2 is typically used to prevent oxidation in finished wine. The traditional method of keeping the wine on lees can also be used but there are risks associated with this method (contamination, quality of the lees). Based on this age-old method, research from the INRAE (J-M. Salmon) showed the potential of specific inactivated yeast to consume oxygen and protect wine from oxidation. A wide range of distinct yeast derivatives obtained from varying yeast strains and different processes for inactivation were tested and measured for their O2 consumption ability.
One exhibited the best consumption of dissolved oxygen in terms of capacity and rate to protect the wine from oxidation during the various steps from post-fermentation processing up to bottling. In order to study its benefits, numerous application trials have been carried out on white wines (during racking, storage, cold stabilization and transport), showing the potential of this biological tool to prevent oxidation after alcoholic fermentation.