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

An architecture for the production of reductive white wines

Traditionally, wine has been made in an oxidative style. But, beginning in the 1950s and 1960s, grape growers and winemakers began to employ new tools to attain specific "stylistic and qualitative ends."

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 were adopted by Emile Peynaud and other scientists in France and, from there, migrated to the US. According to Smith, prior to the 1960s, 95% of California wines were either port or sherry styles. With the introduction of Blue Nunn, and the adoption of the associated technologies in Bordeaux, US winemakers followed suit such that, by 1970, the majority of California wine contained less than 14% alcohol. These tools and techniques allowed the introduction and use of a reductive style of winemaking.

Hydrogen sulfide is the result of a severe case of reduction in wine but, lower down on the scale, Benzene thiol and furfural thiol contribute bread crust, smoke, and struck flint aromas. Fruity thiols provide notes of passion fruit, citrus zest/cat pee, and grapefruit, aromas associated with Sauvignon Blanc (Remy Charest, Fashionable Chemistry ..., nomacorc.com; Jackson, Wine Science). But it is preservation of freshness and fruit aromas and flavor that the winemaker pursues when he/she decides to employ a reductive winemaking style.

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.

The winemaker's plight in producing a reductive white wine
(Underlying picture source: http://cdn.pcwallart.com/)

Before I get into the elements of the architecture, I would like to highlight a Remy Charest report wherein he illustrated a shift to reductive winemaking among Burgundy producers. According to Remy, Jancis Robinson had written about in a shift in Burgundy from buttery, rich, toasty Chardonnays to Chardonnays that exhibited:

• High acidity
• No trace of toastiness or obvious oak
• Leanness on the palate
• The flinty smell of recently struck match.

In her discussions with Jean-Marc Roulot (Domaine Roulot), she was told that this result was largely due to a more reductive style of winemaking, itself a reaction to the premox crisis that rocked the region's white wines in the 1990s.

Remy described the reductive program as:

• Long, slow, delicate pressing
• Protection from oxygen through vinification and aging
• Finishing the aging in tank

Some additional (and widely accepted, though not necessarily reductive) characteristics of these wines include:

• Relatively high SO2 addition (Probably related to the battle against oxidation but may also be linked to the appearance of the struck-match character in some of the wines).
• Fresher, crisper wines resulting from earlier pick dates and moving vineyards to cooler sites.

Reductive white wines are all the rage today but, as Lance Cutler (Achieving Balance in Reductive Winemaking, Wine Business) points out, "Keeping wine away from oxygen can create some vibrantly fruity wines, but this same lack of oxygen might encourage the development of reduced sulfur compounds."

The main considerations in producing a reductive white wine are as follows:

1. Healthy fruit from a cool vineyard. The climate in the vineyard will help to preserve freshness and crispness of aromas while healthy fruit will have an adequate supply of the vitamins and minerals to ensure a successful fermentation. The viticultural factors affecting the supply of yeast assimilable nitrogen include: cultivars, rot incidence, block, vineyard mulch, crop load, moisture stress, and grape maturity level (Zoecklein)
2. Minimize the use of sulfur in the vineyard and ensure adequate time spacing between application and harvest
3. Harvest at night to preserve freshness and flavors
4. Application of inert gases during harvest (mainly CO₂ in dry-ice form)
5. Provide antioxidant treatment to the free-run juice. Most normally ascorbic acid and sulfur dioxide but there is some concern that ascorbic acid switches from protection to oxidative mode over the long term and, as such, is not suited for wines destined for aging. In many cases inert gases such as CO₂ and N₂ are used to protect the juice from oxygen.
6. Measure fermentable nitrogen as too high, or too low, concentrations can result in the formation of undesirable sulfur compounds during fermentation. According to Zoecklein these measurements can be carried out with either Formol titration or a NOPA test.
7. Turbidity should be adjusted such that stylistic goals and aromatic finesse of the wine is achieved. Juice clarity should be measured in Nephol units and should fall between 100 and 150 (Zoecklein)
8. Non-soluble solids concentration should be monitored as both high and low concentrations can result in the production of undesirable sulfur compounds
9. The appropriate yeasts should be selected for the effort as strains differ in their capacity to transform the non-volatile grape derived precursors to odor-active volatiles (Zoecklein)
10. Keep yeast cells suspended in the tank during fermentation in order to allow an even distribution of fermentation as well as to allow full access to distributed nutrients
11. Rack gently under a carbon dioxide or nitrogen blanket. Use an in-line sparging device to sparge the wine with CO₂ or N₂. Add SO₂ to the wine as it is being racked to prevent oxidation
12. No malolactic fermentation in order to preserve varietal character, flavors, and freshness
13. No oak aging in order to continue to continue to deny oxygen access to the wine
14. Select an appropriate closure. According to Remy Charest, "Precise control of oxygen in the bottle, for example by selecting a closure allowing small and consistent amounts of oxygen, can prevent extreme reduction without compromising the more interesting flinty and fruity aromas."

In the cases where the odors are manifested in the wine, remedies include (i) blowing it off through volatility; (ii) inert gas sparging; (iii) precipitating with copper additions; and (iv) fining.

©Wine -- Mise en abyme