The following text and photos are contributed by Flying Goat Cellars Ambassador Faye Walker:

In late March, the season of bud break marks the emerging signs of life on our valley's hillside vineyards. But in the cellar, the movers and shakers behind presses and punchdowns already have their eye on the long game: buds yield fruit, fruit grows to ripeness, and ripe grapes are plucked at harvest time to begin the next vintage.

Winemaking is time-consuming work, and an accurate interpretation of this spring season will keep winemakers well-informed as to when the grapes are ready for their care and attention. In fact, the practice of producing fermented products is one that has taken a very long time to unveil. The union between the sciences of enzymatic mechanisms and physical matter within the realm of wine is not just practical--it is a miracle.

Technically, the process of winemaking begins when the grapes enter the winery.  They are inspected, crushed, and pressed to release the juice. Mechanization becomes more than a tool as maceration comes into play. Maceration, when the juice is in contact with the crushed fruit, facilitates the extraction of flavorings and other constituents located in the grape skins and seeds.  

Enzymes can lend a helping hand as they are released and activated during cell ruptures.  They may synthesize or liberate flavorants and degrade macromolecules, supporting the activity of yeast and bacteria during fermentation. Although the principal by-product of yeast fermentation is alcohol, yeast metabolism also supplies much of the typical bouquet and flavor attributes of wine. As scientists have learned more about the nature of the microbiological aspects of wine development, it has become possible to control the microbial population. The resultant mixture of microorganisms is a key component in achieving a very particular, desired outcome.

Winemakers can leverage the activity of yeast to supply an inoculum of a particular strain with known characteristics. In addition, the wine may be inoculated with a strain of lactic acid bacteria to foster malolactic fermentation. This second fermentation can lend a softness to wine. Malic acid has two acidic groups--but lactic acid only possesses one. As such, the conversion during malolactic fermentation of malic acid to lactic acid reduces perceived sourness. Slowly, under controlled conditions, the wine reaches maturation. Changes in aroma, and the development of a bouquet, come about as the wine is protected from exposure to air.  

All that changes during racking, when the liquid wine is separated from the solids (yeast cells, proteins, salts) that have settled out over time. Racking and clarification processes will inevitably introduce some oxidation.Fortunately, a small dose of sulfur dioxide can help prevent oxidation and microbial spoilage.

Bottling may seem like the end of the line and the launch to market shelves, but there is still time for the wine to continue its evolution within the winery. Wines are normally aged at the cellar for anywhere from several weeks to several years. This allows acetaldehyde (a consequence of oxygen uptake during bottling) to be assimilated with other components. The result dissipates the unpleasant characteristics of acetaldehyde as the compound enters a non-volatile state.  

With such extensive effort going into the production of wine, it is worth taking the time and interest to investigate each step. Why and where does the winemaker choose to adjust each task and action? All those in the cellar are collaborating and keeping tabs on the process. Their technical prowess brings about changes within a fermented beverage as it completes the journey from fresh fruit to liquid refreshment. The subsequent subtleties from one bottling to the next express the thoughts, diligence, and time of an entire world unto itself.

 

Sources and Further Reading

Kosseva, M. R.  Science and Technology of Fruit Wine Production.  Elsevier, 2017.

Mas, A., et al.  Winemaking:  Microbiology.  CRC Press, 2001.

← →

Comments 0