A summary of the various dry white wine styles

In this series I examined the winemaker's challenge in navigating between the twin evils of reduction and oxidation in the construction of white wines; both faults but both having desirable characteristics as you move further away from the edges. The below chart illustrates the dry white wine styles that have been covered in this series. Below the chart are short descriptors of each of the styles along with links to the posts in which they are detailed.

According to Lukacs' research (Inventing Wine), modern wine did not arise until the advent of the relevant scientific and technological advances of the Enlightenment. Prior to that period, wine drinkers consumed oxidized, sour wines that were "fortified" with all manner of additives designed to either slow its decay or make it more "palatable." Lukacs points out that winemaking in the first half of the 20th century was a reprise of thousands of years past -- "a process of letting nature run its course."

But, beginning in the 1950s and 1960s, grape growers and winemakers began to employ new tools to attain specific "stylistic and qualitative ends." On the technical side, the introduction of temperature control and regular chemical analysis allowed greater control over the fermentation and this gave greater impetus to the concept that humans "could and should assume control" of the winemaking process.

Based on Clark Smith's interpretation of the history of that period, the "tools of 20th century winemaking" were stainless steel, inert gas, refrigeration, and sterile filtration (a product of nuclear energy) and this "modern winemaking revolution exploded out of Germany" in the form of Rieslings that were fresh, sterile-filtered, and completely without oxidative characters. According to Smith: "the idea of a light, sweet, fresh, fruity wine like Blue Nun was as world changing as color television." 

These tools and techniques allowed the introduction and use of a reductive style of winemaking. The essence of reductive winemaking is the production of wine without the presence of oxygen. Grapes are harvested from cool regions and the juice is fermented cold in closed stainless steel tanks. Juice is protected, as is the wine, through maturation and bottling. This method is particularly beneficial for grape varieties such as Sauvignon Blanc, Petit Manseng, Chenin Blanc, and Gewurtztraminer that are rich in varietal aromas that can be placed at risk in the face of oxidizing effects.

In the case of hyperoxidation, the deliberate introduction of oxygen into the juice causes enzymatic oxidation of the phenols. The process entails adding large amounts of oxygen to the juice, allowing it to settle, and then racking it from the brown precipitate just prior to fermentation. This oxidation will cause browning of the juice but the phenols will have been polymerized and will precipitate out.

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.

White juice fermented on their skins are differentiated from skin-contact wines 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. These skin-fermented wines, more commonly known as "orange" wines, can be further broken down into two broad classes: traditional and contemporary.

With all of the advantages associated with stainless steel fermentation, oak had to have some overriding benefits for winemakers to continue using it as a fermentation vehicle. And it did. According to Ibern-Gomez, et al*., "Fermentation in oak barrels leads to wines with much more complex sensory properties, largely attributed to the phenols extracted from oak wood." Further, wine is aged in wooden barrels to: (i) enhance its flavor, aroma, and complexity through transfer of substances from the wood to the wine; and (ii) allow gradual oxidation of the wine.

The premature oxidation issue in white Burgundies has been identified by both Jancis Robinson and and Jon Bonne as the engine driving the change in Burgundy from 'buttery,' 'rich,' and 'toasty' Chardonnays to wines that are now characterized by (Jancis):

• High levels of acidity
• No trace of the toastiness of obvious oak
• Leanness on the palate
• The tell-tale flinty smell of recently struck matches.

I have named this style of winemaking oxo-reductive.

The final style-specific installment in my discourse on white wine styles was 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.

©Wine -- Mise en abyme

Hyperoxidation: White winemaking jujitsu

According to dictionary.com, jujitsu (or jiujitsu) is "a method developed in Japan of defending oneself without the use of weapons by using the strength and weight of an adversary to disable him."

Jujitsu training at an agricultural school in
Japan circa 1920 (Source: wikipedia.com)

Hyperoxidation, a white winemaking mechanism which utilizes oxidation effects during the juice phase of winemaking in order to avoid its effects later on in the bottle, is winemaking jujitsu.

I previously described the process whereby white wines are oxidized and the resulting effects. To summarize, the enzyme Tyrosinase (laccase in the case of botrytized must) catalyzes the formation of caftaric acid quinone, the result of the oxidation of the phenol caftaric acid. The quinone reacts with glutathione (a naturally occurring tripeptide found in grapes; and itself a powerful antioxidant) in the juice to form the colorless complex Grape Reduction Product (GRP). Once the glutathione is fully utilized, GRP is no longer formed and oxidation proceeds unencumbered (This process is called enzymatic oxidation. For a fuller description of this process, as well as the non-enzymatic oxidation of wine, see here.). The results of oxidation in white wines are browning, loss of fruity aromas, and gain of aldehydic aromas.

According to Jackson (Wine Science), "In contrast to red wines, the limited antioxidant character of white wines (ed: tannins and anthocyanins provide substantive antioxidant capability in red wines) make them more susceptible to oxidative browning." Further, grape varieties differ markedly in the amount of phenolics released during crushing or extracted during maceration (an extremely important consideration given that phenolics are the main substrate for oxidation activity). The table below shows the levels of flavonoid accumulation during crushing or maceration of selected white varieties.

Table 1. Phenolics released/extracted during crushing/maceration

Variety	Flavonoid Accumulation
Palomino	Low
Sauvignon Blanc	Low
Riesling	Moderate
Semillon	Moderate
Chardonnay	Moderate
Muscat Gordo	Extensive
Colombard	Extensive
Trebbiano	Extensive
Pedro Ximinez	Extensive

In the case of hyperoxidation, the deliberate introduction of oxygen into the juice causes enzymatic oxidation of the phenols. The process entails adding large amounts of oxygen to the juice, allowing it to settle, and then racking it from the brown precipitate just prior to fermentation. This oxidation will cause browning of the juice but the phenols will have been polymerized and will precipitate out.

Clarification is required to reduce the suspended solids to less than 1% by weight in order to remove the major part of the phenolic precipitate. This clarification must be completed before fermentation begins as the precipitate will re-dissolve in alcohol. The clarified juice will retain a brown color but this residual browning will be eliminated by the reducing conditions of alcoholic fermentation and absorption by yeasts (Schneider, Hyperoxidation: A Review, AJEV, 1998).

The brown pigment absorbed by the yeasts during alcoholic fermentation will fall to the bottom of the tank with the lees and can be removed in a post-fermentation racking. Fining and/or filtration can be utilized for additional clarification if required.This process renders the wine less susceptible to in-bottle browning (due to the elimination of the phenols) as well as reduces bitterness in the wine.

Hyperoxidation requires that SO2 additions be withheld from the must as the oxidative enzymes are inhibited in its presence. For example, tyrosinase registers a 90% decrease in activity when 50 mg/L of SO is added to the must. SO2 also reduces caftaric acid quinone and enhances the solubility of phenolic molecules. . These effects will limit the extent and effectiveness of the hyperoxidation. The implementation of hyperoxidation can thus allow for the production of low-sulfur wines.

Hyperoxidation, then, uses the strength of oxidation in the early stages of winemaking to neuter the substrate in the early stages of winemaking and prevent it from becoming an oxidation resource in the bottle. Jujitsu.

©Wine -- Mise en abyme