In simplified terms, the oxidation of white wine is mainly linked to reactions involving certain polyphenols. In the presence of oxygen and/or metals such as iron, highly reactive quinones are formed, which lead to browning phenomena and finally to the precipitation of pigments. Some aroma compounds, such as varietal thiols, can also bind directly and irreversibly to these quinones, resulting in a permanent loss of aroma.
In addition, direct oxidation reactions can lead to the formation of aldehydes, giving wine oxidative honeyed notes when present at high concentrations, in particular 2-phenylacetaldehyde and methional.
In collaboration with Burgundy University (IUVV Dijon, France), we have developed a way of measuring the antioxidant power of yeast derivates based on the nucleophilic fraction, which is globally representative of the addition reaction between the nucleophilic compounds contained in the soluble fraction of yeast derivates and a model quinone. This addition reaction can be considered a neutralisation of quinones. This measurement includes affinity and quantity aspects and is therefore a reflection of the overall antioxidant power of yeast derivates.
Use of this measurement on a range of yeast derivates (Figure 1) enabled us to select the most efficient, namely RO7 and RO4, for the formulation of Extraferm D’fend. While RO4 does not have the highest total nucleophilic fraction, its nucleophile composition is different and seems complementary, thus providing a product with a broader spectrum of action.
Based on these two derivates, we then conducted low-volume trials to identify the right proportion of each yeast derivate in the final product. The following proportions were chosen:
– 80% inactivated S. cerevisiae yeast (RO7).
– 20% autolysed S. cerevisiae yeast (RO4).
Subsequently, the effectiveness of Extraferm D’fend was evaluated under winemaking conditions on different wines (Sauvignon blanc and Grenache rosé from the Languedoc, Chardonnay from Languedoc, and Burgundy).
A white wine (organic Chardonnay from Languedoc, France, without added sulphites) was monitored in terms of oxidation. After fermentation, the batch was separated into two separate tanks: a control tank left on fine lees and the other with the addition of Extraferm D’fend at 30 g/hL without lees.
At T0, T+1 months, and T+1,5 months, we measured the oxidation resistance index using the NomaSense PolyScan C200 instrument from Vinventions, based on linear sweep voltammetry. This index is calculated by Vinventions from EasyOx measurements (determination of easily oxidisable compounds that rapidly take part in oxidation reactions) and PhenOx measurements (determination of total oxidisable compounds). The higher this index, the greater the resistance to oxidation.
The control wine appears to be highly resistant at T0. However, this tank becomes more sensitive to oxidation after the first month. Conversely, the Extraferm D’fend tank acquires resistance to oxidation through its high concentration of nucleophiles with antioxidant properties. This resistance persists over time. After 1.5 months, the Chardonnay with added Extraferm D’fend is as resistant to oxidation as the wine kept on regularly stirred lees. Extraferm D’fend can thus eliminate the need for lees, at least partially.
For the same wine, we monitored the formation of oxidation aldehydes. We considered that the formation of these aldehydes remains a marker of oxidation phenomena, although in all cases, their levels were below their perception threshold.
We show that the addition of Extraferm D’fend limits the accumulation of these aldehydes over time. In the control wine, their concentration increases over time. Extraferm D’fend thus provides significant protection against these oxidation markers.
In other trials conducted on Chardonnay in Burgundy, the emphasis was on sensory analysis to assess the impact of Extraferm D’fend. The three wines monitored (Chablis, Saint-Véran, and Hautes Côtes de Beaune) were vinified in a standardised way (co-inoculation with Fermivin 3C and DUET Soft). Wines aged in the presence of Extraferm D’fend appear fresher with more intense floral and fruity notes at the same aromatic intensity. They are also perceived to be rounder and longer on the palate than the untreated controls. An example of the tasting results is shown here.
Extraferm D’fend thus made it possible to limit the evolution of wine over time and preserve its freshness while increasing its volume and persistence on the palate.
With a highly qualified team of experts in many fields, Oenobrands strives to offer winemakers’ novel and scientifically sound solutions, as well as to highlight the positive synergies between its products.
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