White wine styles: The non-ouillé wines of the Jura

The final style-specific installment in my discourse on white wine styles is the non-ouillé (evaporative loss during aging not topped up) Savagnin wines of the Jura. These oxidatively styled wines are unique to both the region and the cultivar.

Before turning to the Jura wines, let us revisit oxidative winemaking. The effects of oxidation on wine are browning, loss of fruity aromas, and aldehydic aromas. Because of these characteristics, oxidization is widely viewed as a wine fault. But there are strong attempts to differentiate between oxidized wines (fault) and oxidative wines (style). For example, The Wine Doctor defines oxidative wines as "having been made in a fashion which allows oxygen to influence the style of the wine" while an oxidized wine occurs when the "aromatic profile of the wine has succumbed to the aldehydes created by the oxidation of ethanol by reactive oxygen derivatives." Dr. Vino describes oxidative wines as having just enough oxygen while, conversely, oxidized wines have been exposed to too much oxygen during the winemaking process.

The table below shows the characteristics gained and lost in oxidative winemaking.

                                                                      Oxidative Wines

Characteristics Lost	Characteristics Gained
Original Color	Nuttiness
Vibrant tones	Dried fruits
Aromas	Flowers
	Umamai savoriness
	Browning
	Complexity

The Jura Wines website (www.jura-wines.com) differentiates between traditional and Vin Jaune oxidative wines, with the primary differences being the time of aging ( 2 to 3 years for the former, 6 years 3 months for the latter) and the sometimes blending of Chardonnay with the former to add "a touch of finesse."

For these wines, Savagnin is harvested when the alcohol potential is in the 13 - 15% range. After slow fermentation by naturally occurring yeasts, the wines are placed in barriques for aging (the barrels are not tightly filled).

With the passage of time, wine evaporates through the barrel pores. No wine is added to replace the loss -- allowing broader-surface oxygen - wine interaction -- and, after about 2 to 3 years, a thin film of yeast develops on the surface (see picture below).

Aging under the veil (Wikipedia.com)

In this timeframe the winemaker has to make a decision: bottle the wine as "traditional" or go for the Vin Jaune. If the decision is made to do the former, aging is terminated. The traditional Jura wine is characterized by notes such as apricots (fresh and dried), apples (green and dried) and orange.

The wines that are allowed to continue with the aging process do so under a layer of yeast (voile) which is akin to the flor of Sherry fame but is thinner and is optimized for low-alcohol environments. Oxygen loss continues throughout the aging period with sixty-two percent of the post-fermentation wine remaining at its conclusion.

The slight oxygen exposure in this environment results in the formation of acetaldehyde and the aroma compound sotolon (manifests as a curry aroma at high concentrations and maple syrup, caramel, and burnt sugar at lower levels). The winemaker has to be on constant guard for the formation of volatile acidity aromas during aging.

A Vin Jaune wine is dry with bright acidity and notes to include citrus, walnuts, hazelnuts, almonds, curry, and other spices. The wines are bottled in 62-centiliter bottles to reflect the amount of wine remaining after aging loss.

I will summarize the wine styles discussed in this series in a future wrap-up post.

©Wine -- Mise en abyme

Wine styles: Skin-contact whites

In this series on white wine styles, I have treated Champagne and Sparkling wines, reductive wines, and wines made utilizing the process of hyperoxidation. In this post I cover skin-contact white wines.

Skin-contact white wines are recognized by a combination of their residence on the early part of the orange color spectrum, their earthy flavors, and enhanced mouthfeel. These characteristics are the result of macerating the skin of crushed and de-stemmed white grapes in their own juice (i) prior to pressing and (ii) under controlled time and temperature conditions (The procedure is generally carried out under cool conditions in order to limit the growth of spoilage organisms.).

While white juice fermented on their skins are, obviously, in contact with those skins, we differentiate those wines from the ones treated in this post both on the basis of time -- skin contact wines are macerated for between 2 and 24 hours while the fermented-on-skin wine is macerated for weeks to months -- and phase within the production process -- skin contact is a pre-fermentation process while its compatriot extends beyond that to fermentation and, in many cases, maturation.

Maceration refers to the release of constituents from the pomace following crushing and is facilitated by "the liberation and activation of hydrolytic enzymes from crushed cells." Substances extracted include: aromatic compounds, aromatic precursors, phenols and polyphenols, unsaturated lipids, nitrogen, and potassium. At high enough levels, these extractives will produce earthy flavors and enhanced mouthfeel in the wines and will contribute positively to the fermentation processes. The best results are obtained from fully ripe, aromatic grape varieties such as Gewurtztraminer, Riesling, Muscat, Viognier, Chenin Blanc, and Sauvignon Blanc.

What is the makeup of the grape berry skin and what role do the constituent parts play in the makeup of a skin-contact white wine? The berry skin consists of an outer layer with a wax-like coating (cuticle) and 6 to 10 layers of thick-walled cells (hypodermis) which accumulate phenolic compounds in fairly high concentrations as the berry matures (Dharmadhikari, McGlynn). The main components of the skin are phenols, aromatic substances, potassium, and other minerals.

Phenols
Phenolic compounds are:

• Responsible for the color of red grapes and wine
• Involved in the oxidative browning of white wines
• Contributors to taste and astringency through interactions with salivary proteins.

The two major classes of wine phenolic compounds are flavonoids (defined by a C6-C3-C6 skeleton consisting of two phenolic rings joined by a central, oxygen-containing ring -- Jackson) and nonflavonoids (possessing a C6-C1 or C6-C3 skeleton; all numbers following "C" are subscripts). The sources and roles of the phenolic compounds falling into these two classes are illustrated in the figure below and the relative concentrations of selected classes are provided in the table following.

Table 1. Generalized concentration of various phenolic compounds
present in wine

Phenolic	White Wine (mg/L)	Light Red Wine (mg/L)	Full Red Wine (mg/L)
Volatile	Trace	10	40
Hydroxycinnamic acids	150	200	200
Other nonflavonoids	25	40	60
Anthocyanins	0	200	400
Catechins	25	150	200
Polymeric catechins	0	600	900
Totals	200	1200	1800

Source: Kennedy, et al., Grape and wine phenolics: History and perspective,
AJEV, 57(3), September 2006.

Skin contact increases the amount of hydroxycinnamates, gallic acids, and flavonoids. Flavonoids increase slightly with contact time but strongly with temperature. These compounds are of concern because they contribute to bitterness and astringency and also serve as substrates for oxidation in white wines. While there are elevated levels of astringency in skin-contact white wines, they are nowhere near as high as in red wines. First, even though tannin is extracted from the skin of the white grape, the lack of anthocyanins means that only tannin-tannin bonds are formed, a combination that is less soluble in alcohol. Second, during fermentation, most of the tannin will precipitate out, thus limiting its ability to negatively impact the wine's sensory characteristics.

Aromatic Substances
Aromatic substances are located in the skin and layers of cells immediately below it. Examples of these compounds include (Dharmadhikari):

• 2-methoxy-3-isobutyl pyrazine -- imparts bell pepper odors to Cabernet Sauvignon and Sauvignon Blanc
• 4-vinylguaiacol and 4-vinylphenol -- spicy, clove-like, and medicinal odors in some Gewurtztraminers
• Terpenes -- can be found in Muscats and Rieslings.

Fermentation Benefits
While winemakers do not pursue skin-contact because of the benefits that it provides to the fermentation process, they gladly accept what is offered. Maceration (Jackson):

• Improves juice fermentability and enhances yeast viability through its release of particulate matter, lipids, and soluble nitrogen compounds into the juice
• Particulate matter provides surfaces for yeast and bacterial growth, adsorption of nutrients, the binding of toxic C10 and C12 carboxylic fatty acids, and the escape of CO₂
• Improves the production of extra-cellular mannoproteins formed during alcoholic fermentation
• When combined with reduced concentrations of carboxylic acid, facilitates malolactic fermentation by Oenococcus oeni.

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When contrasted with a more traditional white wine, a skin-contact wine may exhibit lower levels of fruitiness and acidity. In addition, the familiar characteristics of your favorite varietal may be hidden behind a spicy character that may now be present.


Bibliography
Murli Dharmadhikari, Composition of Grapes, www.extension.iastate.edu.
Ron Jackson, Wine Science, Academic Press.
William McGlynn, Basic Grape Berry Structure, April 15, 2012, www.articles.extension.org.
Tim Patterson, White Wine Skin Contact, August/September 2013, www.winemakermag.com
Nicola Tazzini, Polyphenols in Grape and Wines: Chemical Composition and Biological Activities, August 9, 2015, www.tuscanydiet.net.

©Wine -- Mise en abyme