Saccharomyces Ellipsoideus (yeast)
Howdy, Hola, and Hello
I was in the winery not long ago loving the smell of yeast and fermentation and fresh grape juice when I remembered a story about yeast I wrote a few years ago. So here it is again, one more time. The cute fable at the end was a story I told in my very first Jeff’s Corner, sometime in early 2010:
Jeff’s Corner 11-2-16
A few days ago, on one of my tours, I was talking about fermentation and a guest asked me for some detailed info about yeast. So, I thought I could share a little more detailed info with all of you as well.
Yeast, a single-cell fungi, is the catalyst that converts the sugar in grape juice into alcohol. These wild spores are everywhere in our natural environment, and have interacted with liquids and foods to our benefit for well over 5000 years.
It wasn’t until 1857, however, with the aid of a microscope, that Louis Pasteur discovered that fermentation was caused by yeast “feeding” on sugar in a liquid. The result was alcohol, with heat and carbon dioxide as a byproduct. It took a magnification of 600x for him to witness this most wonderful chemical reaction.
The yeast responsible for wine is Saccharomyces Ellipsoideus, and there are many, many strains of it that can be found in the same vineyard. The powdery film we see on grapes are wild, or “ambient” yeasts. This is how wine was possible for millennia before Pasteur made his fortuitous discovery. Grapes could be crushed, and the wild yeasts would work their magic without us really understanding what was going on chemically.
Today, science has isolated the best strains of Saccharomyces Ellipsoideus in the laboratory, and can manufacture them in a much purer state than what is found in the vineyard. They can be varietally specific, meaning certain strains work best for certain grape varieties, and can be tailored for certain winemaking techniques.
There is, however, an old-school argument for using the ambient yeasts. They can definitely add more complexity to the wine, and over time a certain vineyard will develop a unique portfolio of its own different strains that will lend an exclusive style to its wine. The problem is that wild yeasts are unpredictable, and can result in a “stuck” fermentation. This is when they stop working before all the sugar is converted into alcohol.
I’m going to sign off today with a cute story about how civilization first discovered wine. Legend takes us back many thousands of years to ancient Persia. The Persians cultivated grapes to eat and drank the fresh juice, but didn’t realize the juice could be fermented into wine.
Enter a young woman in the King’s harem that, for some reason, had fallen out of his favor. Her heart was so broken, she decided her only option was to take her life. But, the dilemma was how to do it. She spied an earthen jar full of grape juice labeled “poison”. It was foamy and bubbled and gave off a terrible smell. She drank a bunch.
Well, rather than her desired result, she actually started to feel pretty darn good She somehow convinced the King to try it and, lo and behold, he started to feel pretty good too! We can only imagine what happened next…