Prevalence and effects of skin contact in Timorasso wine production

As shown in the table below, a significant number of Timorasso producers macerate the must on the skins prior to alcoholic fermentation. Why are they doing so? and why is the Timorasso cultivar a prime candidate for participation in such an activity?

Table 1. Instances of Maceration on skins: Selected Timorasso producers

Producer	Wine	Maceration Period (Hours)
Massa	Piccolo Derthona’ Timorasso	N/A
	Timorasso ‘Derthona’	48 - 60
	Timorasso Cru ‘Costa del Vento’	60
	Timorasso Cru ‘Montecitorio’	60
	Timorasso Cru ‘Sterpi’	60
La Colombera	Derthona	3
	Il Montino	3
Franco M. Martinetti	Martin	36
Ricci	Derthona	72
	San Leto	72
Teralba	Derthona	48 - 72
	Stato	72
Morgassi Superior di Gavi	Timograsso	12
Cascina Gentile	Derthona	24
i Carpini	Ruggiada del Mattino	48
	Brezza d’Estate	48
Massimo Pastura	Timian	16 - 18
Cantina Botazzi	Italo	N/A
	Monterosso	N/A

Based on the figures above, Timorasso producers macerate their grapes for an average of 44 hours prior to alcoholic fermentation. In the case of Massa, the cold maceration is carried out in cement containers, after which the must is transferred to stainless steel tanks for fermentation. Massa is the only producer whom I could identify as also including stems in the maceration.

Skin-Contact Whites

Skin-contact white wines are recognized by 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.). Skin-contact white wines are macerated for hours while skin-fermented whites are macerated for weeks to months. Further, skin contact is a pre-fermentation process while its compatriot extends beyond that to fermentation and, in many cases, maturation.

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.

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 have historically been obtained from fully ripe, aromatic grape varieties such as Gewurtztraminer, Riesling, Muscat, Viognier, Chenin Blanc, and Sauvignon Blanc.

Phenols
Skin contact increases the amount of hydroxycinnamates, gallic acids, and flavonoids in the wine. 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.

The Timorasso Case
Writing in openingabottle.com, Kevin Day characterizes the Timorasso variety thusly: "Timorasso has a rich phenolic character, meaning the natural phenols and polyphenols in the grape yield a lot of aromas, flavors, textures, and characters." In other words, these factors, when coupled with the variety's thick skin, renders Timorasso an ideal candidate for skin contact.

Of the wines I have tasted to date, the one with the most evidence of skin contact was the Cascina Gentile, with its color, tangerine aromas, tannins, spice, and texture attesting to its residence. There is a little bit of a curve ball in this case as the producer ages 1/3 of the production in untoasted French oak barriques of unknown age.

The La Colombera is only exposed to its skins for 3 hours but the color, phenolics, and spice are indicators of this experience. 

I will continue to update this post as I tatse additional skin-contact Timorasso wines.

©Wine -- Mise en abyme