Monday, January 1, 2018

Is Wine a Living Thing?

3 Quarks Daily  by Dwight Furrow  Jan. 1, 2018

The claim that wine is a living organism is something I hear often from people in the wine world impressed with the capacity of wine to evolve. Writer and sommelier Courtney Cochran writes:
Wine, with its clear ties to the lifecycle of plants, its ability to evolve and change (to grow) and its delicate fragility in the face of danger (TCA, oxygen, light), fairly screams "alive." In today's overly sanitized, automated world, could our wine be more alive – perhaps even more ‘human' – than us?
Wine grapes react in a very sensitive way to the conditions under which they are grown. They are a product of an ecosystem as well as a reflection of that ecosystem with the characteristics of the vineyard, community, winemaker and weather living on in the wine—a storehouse of the past, a series of "memories" that are transmitted to the consumer in the flavors and textures of the wine.

Even after the grapes are harvested and fermented, wine as it ages responds to stimuli, adapts to its environment, and like a child, requires guidance and nurturing to reach its potential, expressing its aesthetic worth through its own "evolutionary" path, influenced but not wholly directed by the winemaker.  People in the culture of wine think of it as "living" because wine not only persists but changes and in some cases improves with age. There is a trajectory of maturation that is in some respects similar to the development of living organisms.

The claim that wine is a living thing has also received philosophical endorsement. In philosopher Nichola Perullo's introduction to his edited, online anthology "WineWorld: Tasting, Making, Drinking, Being", he advocates treating wine as a living thing in order to reform tasting practices and gain a deeper understanding of the aesthetics of wine production, especially in light of the fact that wine is ultimately assimilated to our own living tissue. If we take this view on board, wine is best understood not as a commodity but as something with emotional resonance and authenticity, an object we can engage with as emotional beings, not just through analytical tasting.

But is wine really a living thing or is this discourse just making use of a particularly resonant and vibrant metaphor?

Definitions of life in biology are controversial, especially when the task of definition tries to accommodate the possibility of extra-terrestrial life and artificial life. But for most purposes there is a conventional definition that includes several criteria. Living organisms maintain homeostasis, are composed of cells, undergo metabolism, grow, adapt to their environment, respond to stimuli, and reproduce.

Obviously, wine lacks the capacity for sexual reproduction. Furthermore, although wine develops, it doesn't grow biologically since it lacks a cellular structure that undergoes mitosis or meiosis. Neither is its development explained by Darwinian evolution. It thus seems implausible to think of wine as a living thing except in a metaphorical sense since it doesn't share many of the most important characteristics of life. Yet, it isn't obvious how we should understand the criteria this working definition of life employs. 

Mules, most bees, elderly human beings, and the last rabbit on earth are all alive, yet cannot reproduce. Thus, reproduction is apparently not a necessary condition for life. More interestingly, should we discover extraterrestrial beings who pass their genetic code to the next generation via an information processor without sexual reproduction, random mutation, or environmental selection would we deny they possess life if they exhibit all the other characteristics of life? I'm not sure of the answer to this, but I doubt these criteria would any longer have the force of logical necessity were we to make such discoveries.

Of course recently dead organisms also have DNA, proteins, and other components characteristic of life—what they no longer possess are the metabolic processes that make use of these components. Thus the presence of a metabolism would seem to be the central feature of life. Does wine have a metabolism?

The question of metabolism with regard to wine is quite interesting and worth considering in some detail. Metabolic processes are life sustaining chemical processes that convert fuel to energy in order to run cellular processes, maintain cellular structure, and eliminate waste. It is metabolism that enables organisms to grow, reproduce, and respond to their environment. The reactions governing the breakdown of food to obtain energy are called catabolic reactions. The use of that energy to synthesize larger molecules from smaller molecules is called an anabolic reaction. If the catabolic reactions release more energy than can be used by the anabolic reactions, then the energy is stored by building fat molecules. If the anabolic reactions need more energy, they use stored energy to compensate.

Obviously, wine grapes are the result of a series of metabolic processes taking place in the vine and fruit. Fermentation is also a metabolic process since yeasts are living organisms that produce alcohol by consuming sugar producing a waste product, carbon dioxide, in the process. Almost all red wines and some white wines also undergo a secondary fermentation, catalyzed by bacteria, in which malic acid is converted to lactic acid. Thus, up to the point at which the wine is ready to age, there are metabolic processes that explain the development of the wine providing at least some reason for claiming wine is a living organism.

However, much of the development of wine and its resistance to degradation occurs after the yeast cells are inactive and have been removed. Does it make sense to claim that wine in the barrel or the bottle is nevertheless alive? There is much about the aging process of wine that we still do not understand. But it appears to be the case that the process of building structure in a wine, if not metabolic, is a close analogue to a metabolic process. This point will require a brief and overly simplified introduction to how winemakers build structure in wines. To further simplify matters I will focus on red wine.

The ability of certain wines to take up and deploy oxygen when young is a key factor in how a wine will develop through the aging process. This ability depends on the management of tannins. Tannins are phenolic compounds responsible for the drying sensation you get on the finish of a red wine.  However, their purpose goes far beyond providing the sensation of breadth and power we get when tasting. Tannins are crucial in preserving the wine and giving it complexity. Tannins exist as polymers in the skins and seeds of wine grapes. During fermentation when tannins come into contact with acidic grape juice the polymers break down, but during the aging process they reform as wine polymers. Driven by the polarity of water, they aggregate into colloids that in well structured wines should be small and stable. These small, stable colloids ultimately give the wine a soft mouthfeel as well as integrated flavors and aromas, while protecting the wine from oxidation thus enhancing the longevity of the wine as it sits in your wine cellar.

The creation of this fine colloidal structure depends on promoting the early polymerization of tannins while at the same time preventing that polymerization from getting out of control. These goals are achieved via oxygen and the stabilization of color.

Tannins in grape skins are capable of taking up an oxygen molecule and as a result become highly reactive, linking up to other phenols creating a cascade of polymer formation, which protects the wine from oxidation later as it matures. But this polymer formation is controlled by making sure there is sufficient color extracted from the grapes. 

The color molecules cap off the ends of the tannin polymers ensuring that the polymers being formed are short and will feel soft on the palate. This has the added effect of resisting the formation of long chain polymers that will too readily precipitate out of the wine. (This is the residue you find at the bottom of a well-aged bottle.) The presence of oxygen stabilizes the color by creating colloids to which the color can bond.*

Thus, although oxygen in the environment is the enemy of finished wine, causing it to degrade rapidly once the bottle is opened, in the winemaking process it is essential in building structure. This early introduction of oxygen has long been the purpose of barrel aging but can be done via the technology of micro-oxidation today. This is in part why you find young red wines that are soft and smooth on the supermarket shelf. However, although controversial, the early introduction of oxygen allows winemakers who want to make cellar worthy wines to capture and preserve even more tannin since the oxygen increases the capacity of the tannins to bond, thus building structure for aging potential although these wines when young will be harsh and will take time to come around.

Whether the early introduction of oxygen will be successful or not depends in part on the grape varietal. Cabernet Sauvignon has a voracious appetite for oxygen and this is in part why it ages well. Sauvignon Blanc, not so much.

Tannins will continue to evolve over the course of the life of a wine, whether in barrels or bottles. During aging they continue to polymerize into larger molecules with higher molecular weight, bonding with color molecules as well which then drop out of the wine creating sediment in the bottle. The result, if the wine is well made, is a lighter color, reduced bitterness, and a satin-like mouthfeel, depending of course on storage conditions.

As noted above, in a finished wine (ignoring the presence of bacteria and their by-products which may be influencing wine flavor) there are no cells to undergo catabolic or anabolic reactions so strictly speaking this aging process is not a metabolic process. 

But there are a series of chemical processes that use oxygen as a fuel to synthesize larger molecules, the chemical bonds being a form of stored energy. These larger molecules enable the structure of the wine to develop into a coherent system that would otherwise fall apart, supporting esterification, hydrolysis and other chemical reactions that give wine its character, and defend that structure from degradation thus achieving a kind of homeostasis. Although these processes require some intervention from the winemaker to bring elements together at the right time there is a good deal of self-maintenance—once the elements are in place the wine develops on its own, according to its internal structure, with the winemaker making only occasional adjustments. The idea of self-maintenance is itself problematic with living organisms since many social organisms can maintain their biological functions only with the help of others.

The upshot of this description of the chemistry of wine production is that we are in ambiguous territory with the question of wine as a living thing. Using biological criteria, wine may not be alive but it is surely life-like with processes that resemble homeostasis and metabolism. Establishing this likeness does not settle the question of whether wine is a living thing but it clarifies why many have been tempted to attribute life to a solution of chemicals resting in a bottle.

As I mentioned above, this definition of life I have been using is fraught with difficulties. There are living organism that can't reproduce; ambiguous entities such as viruses that can't reproduce on their own and lack a metabolism; and the prospects of artificial life on the horizon will ultimately scramble our definition of life. Thus, many biologists and philosophers of science have defended an alternative model for defining life, called living systems theory, which gets us closer to a better understanding of the nature of wine.

According to Living Systems theory, living systems are self-organizing systems that have the characteristics of life and interact with their environment via the exchange of material and information. A single cell is a living system, but so is a nation. All living systems depend on processes that enable survival and propagation. Some of these systems are metabolic processes which take in and store energy while others process information that enables control of the system. Thus, the defining characteristic of life is the ability to maintain over time a state in which disorder (entropy) within the system is lower than in its non-living surroundings. All living systems have complex organic molecules such as DNA or RNA that enable some of their properties but information flow is also essential. It's the process of maintaining order via self-organization that distinguishes life from non-life.

Perhaps wine is best thought of as part of a living system that includes the vineyard and regional ecology, the winemaker and her staff, and the larger wine community which provides feedback, material resources and aids in the exchange of information. The evolution and reproduction of the wine is a function of the interaction of all these components. The vineyard along with the winemaker and her staff reproduce the wine each year in a way that replicates the signature and identity of the wine. Decisions by the wine community give feed back to the replicators influencing their decisions about wine quality. Thus, reproduction occurs via a web of relationships and is not a function of the internal mechanisms of metabolism and cell division within the wine. Instead wine reproduction depends on a chain of processes that have to do with information flows, planning, interaction with weather and soil, along with the biological mechanisms of the human beings that are components in the system. In the end, it's really the connection to human culture that gives wine its ability to exhibit those features of evolution that we identify with life.
   
 Yet, as I argued last month on this site, wine has "thing power", an ability to evolve according to its own dispositions in ways not intended by the humans that are part of the system. Wine has its own quasi-agency, its own developmental potential, which explains some of our fascination with it and distinguishes it from commodities that are fully under our control. Wine has a degree of independence not only for system maintenance but for development that we typically associate with living things.

Wine is indeed a living thing if we understand "living thing" as the locus of a dynamically interacting system rather than a discrete, mute object.

*For a comprehensive account of this theory of winemaking see  Clark Smith's Postmodern Winemaking.

For more rumination on the aesthetics of wine and food visit Edible Arts or consult American Foodie: Taste, Art and the Cultural Revolution.

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