Tannins in Red Wines
When hosting wine tasting sessions at Texas Wine Collective, a question often asked is “What are tannins in wine, and why are they there?” I was reminded of this when a friend sent me a tasting note posted on www.cellartracker.com website comparing tannin qualities from two different Texas producers – basically, the taster complained about too much tannin in one producer’s wines. Being a subject that my friend and I had recently experienced and discussed, it seemed like a good topic for Carl’s Corner.
The taster that posted on cellartracker.com was very complimentary of one wine saying it was nice with expressive red cherry fruit, a hint of medicinal and herbal character, and just complex enough to please folks with a discerning palate. The comments continued contrasting wines from another producer that was far too tannic, lacked personality (fruit), and were just a mouthful of tart harshness. I think the taster was asking why a winemaker would abandon the most pleasant characteristics of his grape varieties and drift away from the preferred style of a majority of his customers in order to produce over-extracted wines with no personality and a mouthful of tart, unpleasant tannins. Since most of us are not really fond of tannic harshness in wines, this certainly struck a sympathetic chord.
So, the questions become: what is tannin, how does it get into wine, and what makes a wine harsh and astringent? Perhaps most important is to understand that tannins are chemical compounds in plants that basically make them taste bad, providing some protection from herbivorous predators. Daniel Pambianchi, in his referenced Tannin Chemistry article, notes that “tannins belong to a large class of compounds known as phenolics or polyphenols . . . include(ing) anthocyanins, which are responsible for color in flowers, fruits, and red wine . . .“ Depending on where these tannin molecules come from, and their size relative to tasting receptor sites on the palate, they can result in various levels of bitterness or astringency, or a combination. The types of tannins in red wines differ, and their contribution to the wines are different. Without getting too involved in a chemistry lesson, here is a brief overview of tannin types and where they come from.
But first, an aside. To experience tannins in some context other than wine, try sipping some freshly brewed tea without any additives – no sugar, lemon, milk. etc. The puckery, bitterness you get is derived essentially from tannins in tea leaves. High cocoa content dark chocolate is also bitter because of tannins extracted from cocoa beans.
Wine tannins come from grape skins, seeds, stems, and oak barrels used during aging. Softer, more palate-pleasing hydrolysable tannins typically come from ripe grape skins and oak barrels or alternatives. Condensed tannins tend to come from seeds, stems, and, to a lesser degree, skins of red grapes. These can be quite harsh and astringent. Most winemakers work to avoid these by destemming grape clusters, carefully pressing fruit to minimize crushing seeds, and controlling maceration (skin-juice contact).
A number of winemaking techniques are used to add, modify, or minimize the tannic nature of red wine. Harvesting fully, physiologically ripe grapes will help keep tannins on the softer, velvety side. Less ripe grapes will give more aggressive, harsh tannins. Cold soak maceration before fermentation tends to extract more color bodies from grape skins without too many harsh tannins tagging along. Fairly rapid fermentation (6-8 days) at moderate temperatures (65-85oF) helps minimize contact time with seeds, further minimizing harsh tannin extraction. The techniques of punch-downs, pump-overs, and delestage all have an impact on tannin extraction and are used in different ways to control tannins (the references below can help explain these techniques and their use). Finally, the time and temperature of maceration (juice-skin contact) will play a significant role in the amount and type of tannins that end up in the finished wine.
Tannins provide two key benefits to red wine. They serve to bind haze-causing proteins and keep wines clear and stable over the long term. Tannins also serve as antioxidants since they bind oxygen to help prevent flavor and aroma components from oxidizing. A wine’s stability and aging potential are directly related to tannin content and type.
As wines age, tannins tend to polymerize into larger complex molecules that can even get large enough to drop out of solution as sediment. Tannin polymerization also causes red wines to get lighter in color and have an overall softer impact on the palate as the larger molecules do not bind well onto taste receptor sites. Some folks like the character and flavors of older wines in which tannins have polymerized, but others prefer the more youthful fruit aromas and brightness in younger wines. However, if a wine has too much tannin, harshness, and astringency, it can be difficult to appreciate at any age.
The key to a good red wine really boils down to a balance between the components – aroma, flavor, alcohol, acidity, texture, and tannin. Sometimes it seems that a winemaker is just trying to produce a BIG wine with lots of extracts and significant tannin structure to support extended aging. And, often such wines get high praise from some wine writers. However, these wines are difficult to appreciate early on, especially in tasting rooms. If purchasing such wines, one needs faith that they will develop well with age and that fruit character will hold up long enough to eventually balance softer polymerized tannins. Some wines make it, and some don’t. Without a proper cellar for aging or just a distaste for tannins, folks will be better off enjoying mellower, more pleasant wines in the short term.
www.cellartracker.com, Wine Reviews and Cellar Management Tools
Tannin Chemistry by Daniel Pambianchi, https://winemakermag.com/technique/1045-tannin-chemistry-techniques
Skin Contact Decisions by Chik Brenneman (Sep-2021), https://winemakermag.com/article/skin-contact
Going the Distance: Crafting Age-Worthy Wines by Bob Peak, WineMaker Magazine, Oct-Nov 2021, pp 55-57