LAB NOTES
Microbes in the must
Terry Wuerz
“Wine, madam, is God’s next best gift to man.”
Ambrose Bierce, The Devil’s Dictionary
Not half an hour ago, insidious pangs of anxiety took hold, gnawing at a growing part of your consciousness. Questions thrash their way to your forebrain. “Why had you wasted the whole day watching Party of Five reruns when you knew you had work to do?” “How are you going to find the time tomorrow?” And the most self-incriminating of all, “Why does this happen to you every time?” As the will to not work sets in, the thought of lying to your prof to get an extension looks better every minute.
Fortunately for you, and the friends who dragged you out of the house, Chinese wisdom has been dealing with anxiety for over 8000 years. No, not Confucianism or Taoism or Feng Shuism. These doctrines, ancient and enigmatic as they may be, cannot possibly compare with the primeval past (and cures for anxiety) buried in a glass of wine.
The first evidence of winemaking was found on the banks of the Yellow River of China. As you might imagine, wine has enjoyed a long and illustrious history, having made its way into the music and literature of nearly every Old World culture. In large part, this was due to the fact that before hygiene crept into public practice, drinking wine was often safer than drinking water.
Nevertheless, something in the taste and experience of drinking wine intrigues us even to this day. Winemaking techniques have been reformed over thousands of years. Yet, it is only in the past few decades that microbiology and biochemistry have unveiled a clear understanding of what happens to grape juice when it turns into tasty wine.
Over the millennia, much has been made of the grapes grown in vineyards nearly exclusively within 30 to 50 degrees north or south of the equator. The art of growing wine grapes is a secret often closely guarded by individual vineyards.
Once the grapes are grown and collected, they are most often crushed into must, which is a slurry of grape juice, skins, stalks and seeds. This can be done by machines, but the more traditional (and fun) way of making must is to smoosh the grapes between one’s toes. This is often done late at night, to avoid the harsh, fermenting rays of the sun. In Peru, this event has become an all-night party with live music and gallons of wine consumed before the first grape is crushed. Beber vino para hacer vino — wine is drunk so that wine can be made.
After (or sometimes before) separation from the must, the grape juice is ready to begin fermentation. Enter the microbes.
Ostensibly, because it is the process through which wine becomes alcoholic, fermentation is the most important part of winemaking. Functionally, this is the process that turns the sugar in grape juice into ethanol, or drinking alcohol, by yeast. Fermentation was first scientifically documented in 1857 by Louis Pasteur. After Pasteur’s discovery, the best yeast for the job was found to be Saccharomyces cerevisiae. Good work, Louie.
If the yeasts are left to do their business, they will convert all sugars in the grape juice into alcohol. What you have left is a dry, or sugarless, wine. On the other hand, the fermentation can be stopped at some point midway through. This will yield some degree of sweetness to the wine. To make port or sherry, fermentation is stopped prematurely by adding pure alcohol to give the mixture an alcohol content above 15 per cent; this kills the microbes. Other winemakers stop the fermentation process by using a sterile filter, leaving a sweet wine.
Sweetness is important to a wine; it gives it “body” and drastically affects the taste. Some wine connoisseurs will only drink wine with a certain sweetness. Yet, more fundamental to the casual wine drinker is simply whether it is red or white. The explanation behind the colour of a wine is actually quite simple. Grapes, you may have noticed, come in both the red and the green variety. Red wine is made with red grapes.
White wine, on the other hand, may be made with either red grapes or green ones. What determines whether the wine ends up red or white depends upon the amount of contact that the grape juice has with red skin. If it is a red grape, but the juice does not have any contact with the skins once it has been collected, the wine will come out white.
Ultimately, enjoying wine does not require an understanding of the process that goes into making it. Nevertheless, wine is one of humanity’s first inventions, it tastes damn good, and you can’t drink beer all the time — so go ahead, enjoy your wine, and deal with that paper in the morning!
Terry Wuerz, a third-year medical student, in no way endorses the self-medication of anxiety disorders or panic attacks with alcohol.
