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

Traditional and contemporary: Broad categories of orange wines

In my most recent post I characterized skin-fermented white wines as juice fermented and macerated on the skins, seeds, and, in some cases, stems for periods ranging from weeks to months. These wines, more commonly known as "orange" wines, can be further broken down into two broad classes: traditional and contemporary.

Traditional Orange Wines
The traditional method is primarily employed in the Caucasus region today and represents the manner in which white wines had been made for thousands of years. An example of this is the white Kakhetian wine of Georgia where the juice of the white grapes is macerated for months on the skins, seeds, and stems in buried Kvevri. The method whereby this wine is made is illustrated in the figure below.

The grape varieties used in the process (indicated in the above graphic) are characterized by (domainegeorgia.com):

• Relatively neutral flavors (low content of terpene compounds)
• High levels of phenolic compounds in the skin
• High alcohol potential
• Moderate acidity.

The lengthy maceration periods associated with the process dictate that the grapes have adequate levels of sugar and acidity and be "perfectly ripe" (phenolic maturity) and that the grapes, skins, and stems be sanitary (domainegeorgia.com).

The result of the Kakhetian method is a wine with a color that is "dark, almost orange, tea, or amber, often with a pink tinge." The wine's polyphenolic content often exceeds 2000 mg/l, a level akin to light red wines and well above the average 300 mg/l for a European white wine. According to domainegeorgia.com, the sources of the polyphenols are seeds (47%), stems (42%), and skins (11%).

Other kvevri-based white wine production methods encountered in Georgia include the Imeretian (from the province of Imereti in western Georgia; 1/10th the chacha and no stems) and Kartli (central Georgia; 1/3 of chacha plus stems). The avoidance of stems renders the Imeretian method less tannic than the Kakhetian while the Kartli method falls somewhere between the two (domainegeorgia.com).

Contemporary Orange Wines
These wines originated in the Italy-Slovenia border area around Friuli-Venezia Giulia, pioneered by producers such as Gravner, Radikon, Movia, and others who were inspired by the ancient winemaking techniques of Georgia. According to Appel, these wines:

• May be fermented and aged in a variety of vessels, to include wood or clay
• Are often open to the elements until aging begins
• Utilize native yeasts for fermentation
• Undergo long, slow, natural fermentations.

Some of the cultivars employed as raw material for these wines include Ribolla Gialla, Chardonnay, Riesling italico, Malvasia, and Pinot Grigio.

The extended contact with the grape phenolics during the long. slow, maturation and aging results in wines that are characterized by (Appel):

• Exceptional richness and body
• Striking, fascinating tannins
• Ageability
• Savoriness
• Intensity
• Unique flavors to include tea, baked apple, honey, nutcake, sourdough, cider, etc.

Michael Franz points to the region of Collio in the Friulia-Venezia Giulia region for great orange wines. The wines there are made from late-harvested Ribolla Gialla which are macerated for 1 - 4 months, after which they are pressed and placed into large old casks for a number of years before being bottled for sale.

Ribolla Gialla orange wines from the pioneering Stanko Radikon are considered to be among the best of this wine style. Radikon ferments destemmed grapes in oak barrels with natural yeasts and no temperature control. At the conclusion of the fermentation the vats are filled and closed. The wine remains in contact with the skins for 3 to 4 months after which they are aged in large oak casks for 3 years and in bottle for 1 year.

A contemporary, non-Friuli orange-wine producer is the Etna-based Frank Cornelissen. The core objective of Frank's viticultural regime is the production of grapes that lead to profound wines. The practices to promote this goal include: crop management through pruning; tailoring of  bunches to concentrate sugar; handpicking of defective grapes; late harvests; and multiple passes through the vineyards to ensure harvesting of fully ripened grapes.

In the cellar, Frank does not add sulfur either to combat oxidation or to combat micro-organisms. Wines are fermented by indigenous yeasts in small, food-grade plastic tubs. To ensure vintage integrity, all yeasts resident in the cellar are killed prior to the start of wine production. Fermentation is conducted with yeasts brought in from the vineyards on the grapes.

Both white and red wines are fermented with skin contact. His Munjebel bianco 2014 is a white wine made from 60% Grecanico Dorato and 40% Carricante. The grapes for this wine are grown on 40+-year-old vines grown in the Calderara soprano and Borriglione vineyards. A total of 4000 bottles of this wine is produced annually. This wine is amber in color and, when tasted, exhibited florality, spice, and a savoriness on the nose. Savoriness flows through to the palate. A textured wine with great acidity and a long finish.
**********************************************************************************************************
Skin-fermented wines have spread way beyond the "old world" into every nook and cranny of wine production. While these wines will probably always occupy a relatively small niche of the white wine world, they have long thrown off the coat of "oddity."

Bibliography
Joe Appel, Skin-contact in winemaking turns an ordinary white into a tantalizing orange, Portland Press Herald, 8/31/16.
Domaine Georgia, Winemaking in Kvevri, domainegeorgia.com
Michael Franz, Collio, Italy's Best Region for White Wines, Wine Review Online.

©Wine -- Mise en abyme

Skin-fermented white (orange) wines: Another arrow in the winemaker's quiver

In my post on skin-contact white wines, I differentiated between that specific style and the more expansive skin-fermented style. I characterized the former as juice macerated on the skins for between 2 and 24 hours, during the pre-fermentation phase, while the latter is macerated for weeks to months, extending through the fermentation and, in some cases, maturation phases. I examine skin-fermented wines in this post.

Skin-fermented white wines are treated in the same manner as are red wines; that is, fermentation of the juice in the presence of grape skins, seeds, and, in some cases, stems. The key difference between these wines and conventional white wines are the extractives from the skins, seeds, and stems (if stems are included). The key difference between these wines and skin-contact wines are the greater concentration of extractives from the skin and the extractives from the seeds and, if utilized, the stems.

The figure below illustrates the flavonoid phenolic compounds in wines and their sources. I have described the skin and its extractives in the previously mentioned post. I will provide a brief summary of the seeds and stems in the following.

Seeds
Grape seeds are comprised of an outer seed coat, an endosperm, and an embryo, with the seed coat containing relatively large concentrations of tannin. Jackson stipulates that the predominant phenolics in seeds are the flavan-3-ols catechin, epicatechin, and procyanidin polymers (the latter a condensed tannin).  The tannins in the seed walls are more polymerized, and contain a higher proportion of epicatechin gallate, than those in the inner portions. Phenol levels in the seed are higher than in the skin or stems (60% versus 20% each) but they are seldom extracted to their "full potential" during wine production due to the lipid coating which retards tannin extraction until alcohol content becomes a facilitator (Jackson).

Seed tannins weigh, on average, 3.5 - 5 mg per berry while skin tannins weigh in between 0.5 and 0.9 mg. Seed tannin polymers are shorter than skin tannin polymers (the longer the tannin chain the higher the astringency) yet seed tannins are perceived as harsher, greener, and more astringent due to a greater degree of galloylation.

Grape tannins accumulate during the first period of berry growth with skin tannin synthesis beginning earlier than seed tannin synthesis and then ending with the conclusion of the first phase of growth. Seed tannin synthesis continues into the early period of berry ripening before concluding. Both skin and seed tannins continue to mature during the berry ripening phase.

Skin tannins release early and easily but then plateau. Seed tannin release is slow, steady, and long and requires alcohol as a solvent. Tannin extraction will continue throughout fermentation with the ratio tilting in favor of seed tannin somtime during the process.

Stems
Grape stems are comprised of cellulose (approximately 30%), hemicellulose (21%), lignin(17%), tannin (16%), proteins (6%), and other constituents. As was the case for seeds, stem flavan-3-ols occur primarily as catechin, epicatechin, epigallocatechin, epicatechin-gallate, and condensed tannins (procyanidin oligomers and polymers).

In a study of wines made with varying levels of stem inclusion, Suriano, et al., came to the following conclusions:

• Wines vinified in the presence of stems were higher in tannins, flavans, vanillin, and proanthocyanidins
• Stems conferred more structure and flavor to the wines
• Stems facilitated must aeration thus promoting synthesis of higher alcohols and ethyl esters by the yeast.

In addition to the foregoing, it should be mentioned that the stems reduce the compactness of the cap thus providing pathways for carbon dioxide escape during fermentation and wine flow-through during pumpovers. On the minus side, stems in the cap increase the difficulty of manual punchdowns.

Stem condensed tannins are also considered to be very bitter and astringent and fall between skin and seed tannins in size. Green stems should be avoided as it will take years for the wine in which it is included to mellow out (Pambianchi).

Summary
To summarize (Gil, et al.):

• Seeds and stems are major sources of phenolic compounds that condition the final composition of the wine
• Seeds release significant amounts of flavan-3-ol monomers as well as proanthocyanidins with relatively low mean degree of polymerization and a high percentage of galloylation
• Seeds also increase astringency and bitterness and generate a slight but significant decrease in ethanol content, probably through the release of potassium and water
• Stems also release flavan-3-ol monomers and proanthocyanidins but their composition differs from those of the seeds
• (+)-gallocatechin replaces (-)-epicatechin
• Procyanidins had a higher mean degree of polymerization than those from seeds and a higher percentage of prodelphinidins
• Stems significantly increased the pH and decreased the titratable acidity and ethanol content (probably through the solubilization of potassium and water) of the finished wine.

In my next post I will discuss two broad categorizations of skin-fermented white wines.

Bibliography
Mariona Gil, et al., Influence of Grape Seeds and Stem on Wine Composition and Astringency, Journal of Agricultural and Food Chemistry, August 2016.
Herraiz, et al., Effects of the presence of skin during alcoholic fermentation on the composition of new volatiles, Vitis 29, 1990.
Ronald Jackson, Wine Science, 3rd ed., Academic Press.
M. Jose Jara-Palacios, et al., Detailed phenolic composition of white grape by-products by RRLC/MS and measurement of antioxidant activity, Talanta, 2014.
James A. Kennedy, Grape and wine phenolics: Observations and recent findings, Ciencia e Investigacion Agraria 35, 2008.
William McGlynn, Basic Grape Berry Structure, articles.extension.org, April 15, 2012.
Daniel Pambianchi, Tannin Chemistry: Techniques, winemakermag.com, April/May 2011.
Jean-Marc Souquet, et al., Phenolic Composition of Grape Stems, Journal of Agricultural and Food Chemistry, May 2000.
S. Suriano, et al., Major phenolic and volatile compounds and their influence on sensorial aspects in stem-contact fermentation winemakingof Primitivo red wines, J Food Sci Technol 53, 2016.


©Wine -- Mise en abyme