THIOLIC ROSÉ WINES

HOW TO ENSURE AROMA AND COLOR STABILITY

Rosé wines, a market of many nuances that has seen record sales and an unprecedented growth rate in recent years. At the origin of this success is the winemaker's ability to identify the profile of the vinified product, both in terms of color and aromatic profile.

Aromatic thiolic rosé wines

This type of rosé is increasingly popular with consumers. These are wines that can be elaborated starting from grape ripening degrees that allow the preservation of the aromatic precursors of these compounds. We are therefore talking about early harvests that favor freshness and that allow wines with aromatic precursors and a balanced alcohol content to be produced.

The management of harvesting and maceration

From the very beginning of winemaking, the first factor to take into consideration is oxygen management, which is not a critical point if crates are used for manual grape harvesting, while in case of mechanical harvesting it is very important to use antioxidants, such as AROMAX Gal, to minimize oxidative phenomena in red grapes and protect them from the risk of the onset of vegetable odors, and, even worse, oxidize a good part of the precursors present in the grapes/mosts.

As soon as the grapes are mustered, an ideal practice for extracting the precursors of thiol aromas and promoting olfactory notes in the wine is press maceration, taking care to add CO₂ to reduce the effect of oxygen on quality during maceration.

Another possible practice is partial prefermentative maceration of whole grapes at low temperature in crates or in tanks, at temperatures of about 5 °C for 24 hours. The specific AEB product we suggest using at this stage is ENDOZYM Cat-0, to be added at the filling of the press or in the tank, or just before going into the same if tank maceration is carried out.

The use of ENDOZYM Cat-0 in maceration has several benefits:

• promotes the extraction of juice from the skins and subsequent clarification or flotation, minimizing the extraction of polyphenols, such as catechins, which would adversely affect the color and aromas of the wine;
• makes it possible to increase the fraction of the so-called draining must, which, when subjected to proper maceration, retains most of the odor compounds, with a limited cinnamic acid content;
• increases the extraction of must even if the press is used without removing the pressure. This practice increases the production of a high-quality must from the limited presence of lees.

The stabilization of thiolic rosé wines over time

The stability of a rosé wine from a quality point of view must rely on a fundamental aspect, which is the reduction of levels of phenolic acids, present in the skin and within the grape. These compounds, which individually do not pose a problem, can pose a danger when they bind to tartaric acid to produce esters, a phenomenon that has little negative impact on color but a high impact on aroma.

Olfactory cleanness and oxidative issues

A key role in the production of thiolic rosés is played by the purification of enzymes from cinnammilesterase activity, which is the origin of characteristic Brettanomyces odors such as volatile phenols.

Not only that, these compounds, by binding to quinone, promote the appearance of orangey, brownish hues, which diminish color quality.

Moreover, quinones have the ability to block the aromatic precursors of thiols, and their oxidation creates hydrogen peroxide, oxidizing the thiols in the disulfide form.

Also undermining the qualitative stability is the oxidation of ethanol to ethanal, which combines with SO₂, nullifying the antioxidant action.

To minimize the level of phenolic acids, which can be found in wine, either in free or combined form, it is recommended to treat freshly mulled musts before clarification or flotation with:

• Specific clarifiers for polyphenols: POLYGEL W, VE-GEL, VEGA-GEL, MICROCEL, MICROCEL AF
• Adsorbent bentonites: BENTOGRAN, BENTOGRAN Rapid, MAJORBENTON B
• Carbons: DECORAN XL

Clarification of thiolic rosé wines with AEB products must be tailored to each must family in the winery and is intended to remove as much as possible of the phenolic compounds that compromise the quality of the finished wine and its shelf life.

In this sense, the use of decolorizing carbons is considered to be the most chemically but also qualitatively impactful. The carbons, in fact, if not dosed with particular care, can deplete the must of aromatic precursors, irrevocably compromising their quality. It all depends on the varieties being worked with and the progress of ripening.

In maximizing thiol-related hints, very precise clarification must be carried out, bringing the must to fermentation NTU between about 80 and 100, ideal turbidity for thiol formation in varieties where the presence of their precursors is limited. Finally, we recommend adding MICROCEL if during AF you realize that the dose used was not sufficient to remove unwanted compounds.

Alcoholic fermentation of thiolic rosés

Immediate initiation of AF avoids oxidative phenomena in the must; therefore, it is necessary to rehydrate and acclimatize the yeasts as best as possible, employing equipment from the REACTIVATEUR 60 line.

To enhance the thiol notes at this stage we suggest using yeasts from the FERMOL line. Specifically: RED BOUQUET, PMD 53, LIME, CANDY (if an amyl note is desired), SAUVIGNON and IPER R.

Let's not forget nutrition. And here we have the FERMOPLUS line, with: INTEGRATEUR 20KD 2.0 or DAP FREE as the first step, and then SAUVIGNON, ROSÉ or RED BERRY.

Numerous trials have also shown how another AEB yeast, LEVULIA Torula, when combined with FERMOPLUS Non Sacch, is able to ensure the development of thiol hints valued by the market.

The type of yeast used for enhancing thiol notes is closely related to the definition of must fermentation temperatures (the ideal T range is 14 to 18 °C) and the nutrient used.

Finally, particularly appreciated in rosés with a thiol profile are hints of grapefruit and lime, hints favored by the use of a new AEB tannin called PROTAN LXP. In support of organoleptic and color stability, however, are yeast derivatives rich in glutathione, such as ELEVAGE Glu added at the end of fermentation.

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THIOLIC ROSÉ WINES

HOW TO ENSURE AROMA AND COLOR STABILITY

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