Friday, June 6, 2008

"Fighting wine ignorance one person at a time"

Learning module - Ageing Wine

Many readers want to know how their wine will (or can) age. Most wines today are made to be consumed within a short period after release. They are often made from very ripe grapes (with low acidity and ripe, soft tannins) in order to be more immediately accessible. This comes at the cost of longevity. The goal in this approach to wine making is an immediately satisfying wine rather than the deferred gratification of a complex and nuanced wine after extended cellaring.

Determining how long a wine will age is often a gamble. Ultimately, it is not possible to absolutely and precisely predict the lifespan of a wine. This module details the approach to estimating a wine's longevity.

Three loose rules of thumb.

One common rule of thumb for estimating longevity is that however long a wine takes to reach peak maturity is the length of time it will taste its best. Obviously, some wines, even red wines, reach maturity quickly. Nonetheless, one can roughly project the life term of a wine by considering its level of maturity and integration against its current age. At this point, some experience is necessary to serve as a reference point of when a particular wine from a specific region is at its peak.

Another way of gauging age worthiness is to consider the the degree of maturity or development of a wine at the time it is tasted as compared to its character just after it was bottled. One can think of similar wines (already tasted) from the same region or vineyard, producer and vintage as reference wines. Young wines are generally exuberant and bursting with flavors and energy. They may go through a phase where they are closed, and austere but then, with age, they blossom. The taster has to think about how lively and youthful a particular wine tastes at a given time. One has to use their experience to estimate a period of time necessary for a wine to "calm down", integrate and reach the level of maturity typical of its style and region. Fine, mature wines are composed, graceful, nuanced and integrated. Wines past their prime are dull, withered and faded. One has to consider how long a given wine has take to reach its particular stage of evolution in the bottle. The shorter the time between harvest and peak maturity, the shorter the overall lifespan. This, of course, requires some experience in wines in general and the wines from the same year and growing region as the wine in question.

There is some disagreement about the value of using the the length of time a wine needs to unwind or open up in the decanter as an indicator of longevity. We prefer to look at another character of a given wine during assessment. This involves leaving some wine out overnight - in an opened bottle and in a glass. The degree of decline overnight gives an indication of age worthiness. If the wine is as vibrant and lively (or more so) the following morning, then this tends to indicate that it will last for at least several years when cellared properly. This process helps approximate or simulate the changes seen with ageing and is based on the concept of a wine's reductive capacity or reserve - the ability of its ingredients to withstand oxidation with minimal change or deterioration. If the wine tastes oxidized and falls apart by the morning, it is not likely to be good past one to three years (at most) with optimal cellaring.

Taking it apart for deductive approach.

Some wines do display hallmark characteristics indicative of longevity. In general, in order for a wine to last over the years it must have sufficient levels of flavor compounds (extract), acidity and tannins.

The younger the wine, the fresher, more vibrant, exuberant, more concentrated and less integrated its fruit aromas and flavors are. (Concentration should not be confused with sweetness or body). Fruit flavors fade with time. Big, exuberant aromas and flavors early in a wine's life are not enough. The wine has to be made from grapes picked at the right time (growing location and weather play a role too). Wines made from over-ripe grapes do not age into graceful, fine elixirs nor do they have the same longevity as wines made from grapes picked based on prudent harvesting decisions. Each variety has its signature or characteristic aromas that distinguish it as a Cabernet sauvignon or a Syrah or a Pinot Noir. There is some variation depending on clones in the vineyard, location and weather. The small differences notwithstanding, this distinguishing character is called varietal typicity. However, the more distinct and typical of the best examples of the variety (in its youth) the aromas are (allowing for clonal variation and blending of different clones in the finished wine), the more likely the fruit was grown in the right place, the vintage was favorable and the fruit was picked at the right time to make an age worthy wine.

The flavor and aroma compounds in ample supply are not enough. Something needs to preserve them. This is thought to be accomplished by acidity and tannins. High acidity (high TA and low pH) contribute to a wine's longevity. The younger the grape at harvest, the higher the acid levels. While good acidity (high TA and low pH) are useful indications, the nature of the grape that must be considered. A Pinot should have higher acidity than a Syrah. Finally, one must take care to not confuse the acidity of the finished wine with the acids in the grapes at the time of harvest. Acidulation, a commonly used technique, is the addition of certain acids (which occur naturally in grapes) to the fermenting wine to perk up its acidity. A wine made this way will age differently than one with naturally high acids.

Tannins are the third factor in the longevity equation. They are present in far greater quantities in red wine grapes. Hence the tendency of red wines to have greater longevity. This group of chemicals includes the molecules responsible for color aroma and flavor. They come from the skins, the seeds and stems (if whole cluster fermentation is performed). All evolve as the grape matures. Seeds turn from green to yellow to brown as the grape matures and senesces. Stems go from plump, firm and green to soft and withered and then dry and become brown with time brown. Along each point in this evolution, different flavor and texture characteristics of tannins can be seen. In seeking to define "physiologic ripeness" tannins have been generally divided into "green"' and "ripe" categories. This is a generalization and, as such, is as limiting or misleading as it is helpful. There are vague associations of green as astringent and bitter and ripe as supple or smooth, but those are generalizations do not give all the answers.

It is important, at this point, to distinguish between “astringent” and “bitter”. Astringent is the dry, puckery feeling of a thirsty sponge sucking up all the water from your mouth (see here for a longer discussion). It is a tactile sensation. Bitter, on the other hand, is a flavor and is sensed at the back of the tongue. It can contribute to a hard, harsh or rough character of the tannins, but one must first look at the two qualities separately before making a final assessment of a wine's tannins. Astringency, as a characteristics of tannins, is due to their tendency to bind proteins. This is why big, red wines like Barolos, Syrahs, Petit Syrahs and Cabernet-based blends (which are very tannic) go well with red meat – which is is big on protein. The younger the wine with long cellaring potential is, the more astringent (but not necessarily bitter) it generally is. Bitterness will probably not change much. Getting a sense of where the wine's tannins are in their evolution - relative to the acidity and level of development in the fruit - by examining their astringency and texture is our approach to estimating age worthiness.

Although there is some research now suggesting otherwise, younger tannins are believed to be not polymerized (combined into chains or clusters of chains of the same molecule), or at least polymerized to a lesser degree than older tannins. Each tannin molecule has more places on it where it can bind to proteins. Since young tannins are thought to be non-polymerized, or polymerized to a lesser degree, they are believed to feel more astringent than they do in the same wine after some aging. They produce this astringent sensation by binding to the salivary proteins and to the proteins on the surface of the cells lining your mouth. This compromises the ability of saliva to lubricate the mouth. The intensity of the resulting astringent sensation is thought to be proportional to both the total amount of tannins and the degree to which they are not polymerized.

Wine is believed to be a very active chemical system in constant flux. Tannins are believed to polymerize with time in the bottle (forming a sediment on the side of the bottle) and become silkier, supple and less astringent as a result. Evidence exists that there is both polymerization and de-polymerization of tannins occurring in wine at the same time. In the very slow process of polymerization, it may be that tannins they take up the oxidative chemicals in the wine. This in turn may be a basis (at least in part) of how tannins preserve the other components of a wine. Before a wine is bottled, it spends some time in a barrel. Air slowly seeps in through the grain of the wood of the barrel. Because this process mellows a wine, it is thought that the oxygen which bleeds into the barrel interacts with the tannins, and helps them polymerize. This is can be augmented or accelerated by micro-oxygenation (slowly infusing minute amounts of oxygen into wine) which to softens and mellows a wine. This is not a very well understood process. By comparison, délestage is a tannin management method whose goal is to reduce or eliminate bitter or "green tasting" tannins.

In assessing a wine's tannins one must look at both astringency and bitterness but not confuse the two. When one thinks of the level astringency and texture of the tannins in the context of the wine's age and method's used in making it, a general sense of longevity can be gained.

Final points.

All this speculation is contingent on proper cellar conditions. These include: a steady temperature of 55-60 degrees Fahrenheit, about 60% relative humidity, darkness and protection form vibration (wine bottles should not be turned periodically as some suggest). Room temperature is problematic, particularly in the summer. When wine reaches a temperature of 80 degrees Fahrenheit, it begins to "cook". This is not in the bubbling and boiling sense but, rather, it refers to a rapid deterioration of flavor components resulting in a "cooked" flavor profile. Additionally frequently alternating temperatures between two extremes are also detrimental to longevity.

Finally, closures are very influential. Screw caps and crown caps form the tightest seal resulting in the slowest rate of oxygen entry. They are essentially on par with natural cork closures. Synthetic cork closures, on the other hand, actually allow the highest rate of oxygen entry in to the bottle of all types of closures. The faster oxygen enters a bottle, the faster the evolution and decline of the wine inside. While it is not clear how screw caps and crown caps can perform (in the long term) in a cellar, they are used primarily because they deliver a stable and fresh wine to the consumer by preventing rapid deterioration.

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