|Fermentation: a 'natural' physical change with happy results.|
Science. Even an exploratory thought of it was never of interest to me, and even the baking soda fueled rockets of childhood that left the family yard were a just a passing flight. In high school when given the choice between chemistry and physical science I chose the latter and was lucky to just get by. As a result, the basic wine science required by the many industry examinations remained a very challenging and difficult understanding for me to fully comprehend. Plus, I don't think my brain works that way. Perhaps I am more of a visual artist, recognizing patterns, textures and contrasts. But as much as I love wine, I am beginning to enjoy the relationship that wine has always had with science. Wine, of course, is life in a bottle!
A simple grape holds the physical properties that allow it to reflect the environment in which it was grown, give it the elements to produce healthy fruits and juices, and can also create an intuitive and developing life apart when captured as wine. On its skin sit millions of native yeasts that in the right environment will feed upon its hosts sugars(6 carbon- fructose and glucose) and a resulting ferment creates an amazing physical change. With the resulting by-product of CO2, the catalyst produces alcohol(ethanol); plus a ferment will contribute more personality and character to the juice, built on the backs of its principle(among many) acids(tartaric and malic) and developing organic compounds. These magic yeasts need air to do their work, and yet too much air will drastically change the character, even the nature of wine(think vinegar from acetic acid). Thankfully, it is a controlled fermentation that makes wine apart, more evolved than just grape juice.
The resulting acids add important balance to the 'fruity-ness' of the wine, inhibit the production of bad bacteria, and unfold to bring out a wines flavor(personality). Once fermented, oxygen becomes their enemy, or their friend, depending on the style of wine created. Oxygen can be safely hidden from outside the must cap of an open top fermentor, or measurably introduced to produce a unique veil of yeast(flor) to slow the wines' change. White wines that are about freshness hide from too much oxygen, while red wines in barrel measure an oxygen exchange thru porous barrel staves or bungs to purposely create oxidative and reductive environments. Magically, all the natural accidents happen, and wine appears. It tells of its nurturing, the hours in the sun and its journey to the bottle.
|All that CO2 must go somewhere!|
Anthocyanins: water soluble plant pigments, influenced by strength of the acids
Aromatics: the results of volatile esters(good & bad) produced during and after fermentation.
Esters: result of ethanol & acid at the same party, and you smell them.
Fusel alcohols: natural heavy alcohols come along, and may not be wanted.
Malic acid: think Granny Smith or Pippin apples, and you'll be fine.
Mercaptans: volatile sulphur compounds stink
Polyphenols: bitter tannins, anti-oxidents and the coloring compounds held in grape skin
Tartaric acid: principle acid that crystallized to become cream of tartar
Raise a glass to the marvel of science, and Cheers!