Winemaking: Science or Magic?

Red wine necklace --
 (from madewithmolecules.com)

Last night I attended a networking event advertised through the San Diego Biotech Network and sponsored by PGC200.org (link).  The topic of discussion?  The Biotechnology of Enology (Oenology for you Brits).   Some days, when experiments are particularly uncooperative, I wonder what it would be like to own a winery.  Seems like a good fit since I like wine, I like science, and I like growing things.  However, I have always been intrigued by how different wines can taste even though they are made from the same grape.  There is also huge variability in different vintages from the same winery.  And unlike beer, if you let wine sit in a bottle for a few years, it can become extraordinary.   How does this happen?  I mean, how hard can it be?  Pick some grapes, stomp them with your feet, pour the shit in a vat and wait a couple years.  Seriously.  The grapes come from the same plant each year so their genetic makeup is the same.  The winemaker knows how to prepare the grapes, add the yeast, control the temperature, uses the same bins, etc.  Budweiser can make the same beer year after year… why can’t the winemakers?

Reading the abstract for the talk (biochemical pathways, genetics, chemical reactions, blah, blah, blah) I figured science must have the answers to this.  Then I saw the bit about wine tastings and immediately signed myself up.  I’ve been to a ton of scientific conferences and let me tell you, almost any mind-numbing talk can be improved with a glass or two of wine.   The speaker was Kerith Overstreet, co-founder and CSO of Bruliam Wines (link)(Bruliam sounds like something off the periodic table, but is actually a portmanteau of her children’s names).   Her talk was nothing short of fantastic.  Life-altering, in fact.   She was an MD (pathology) before switching careers to winemaking and had a sense of humor as dry as a good cabernet.  We gathered in a beautifully modern conference room and during the reception, we admired the views of the surrounding mini-mountains.  She started us off with the 2009 Hayley Pinot Noir.  It was light and pleasant (she described it as feminine).  Lucy, my partner in crime on this trip, described it as kind of bitchy.  Not sure what that means but she knows a hell of lot more about wine than I, so I just nodded knowingly.  Maybe it had too much whine.  (Thank you, thank you.  I’m here all week.) Next up was the 2009 Doctor’s Vineyard Pinot Noir.  This was from the Monterey area (Santa Lucia Highlands) and we both agreed it was really nice.  Bruliam Wines has only been operational for three years and even I can tell that these wines kick ass.  After a couple glasses of wine and some great food, we were all ready for a nap – I mean, the talk.

(The scientifically squeamish may want to sit down now.  Or skip ahead a few paragraphs.)

Kerith started us off gently, talking about how the root stocks were different from the vines and that the two are actually selected independently, like picking out a top and a bottom.  Then she went into fermentation like a bat out of biochemical hell.  Early on, it’s all about the glucose pathway.  The added yeast converts sugars to ethanol and the genetic composition of the yeast determines the speed and efficiency of the process.    Alcohol is toxic to yeast, so there is a beautiful biochemical feedback loop at this stage.  As the yeast becomes stressed, pathways are activated (and are up-regulated by the dropping sugar concentrations) that release fatty acids, sterols, and other chemoprotectants (let’s call this ‘the good stuff’).  During the fermentation process, oxygen is bad – unless you are trying to make vinegar -- however, there is always a little bit in there and so some of ‘the good stuff’ gets oxidized to make “magical stuff” (ie, tannins).  These are my scientific terms, not Kerith’s.  You know when a girl gives you that “come hither” look?  That’s the female equivalent of a tannin.

Pretty simple so far, right?  Just control the reaction and you get your wine.  Not quite.  After the yeast is done, you then have to add bacteria for the second fermentation.   This step stabilizes the wine by converting nasty biochemical byproducts to more storage-friendly chemicals.  In the case of red wine, this is also where the magic occurs.  As the sugar level is crashing and the yeast are starting to die, you sprinkle bacteria ‘like fairy dust’ into the fermenting goo.  Choice of strain is again critically important (homofermenters, heterofermenters, malolactic strains, zzzzz) but whatever you add activates different biochemical pathways which, in turn, gives you different levels of “good stuff” and “magical stuff”.  Timing and balance is everything.   You can’t let the yeast or the bacteria over-process the biochemical byproducts or you wind up with wine that is “all alcohol and no sex”.   I’m calling these chemicals “magic” because honestly, people don’t know what most of these chemicals are or why they are important.  But they are mission-critical for body, flavor, mouthfeel, and aging, particularly in red wine.  These magic tannins are the key to turning a good bottle of cab into a mind-blowing experience.  How does that work?

Catechin - one of the magic molecules

One wine characteristic I know well is the dry, leathery feel of a cabernet.  It makes your mouth feel weird and some really young cabs are like drinking liquid desert.  The a-ha moment in Kerith’s talk came at the end when she was talking about aging.  When a cab is young, there are a lot of tannins in there and the taste can be very harsh.  That sensation in your mouth is because tannins bind very strongly with proteins in spit, so they cling to the sides of your mouth.  One of the magic tannins is from the flavin-3-ol subgroup  of flavinoids (not to be confused with the famous rapper) and is commonly known as catechin.  Catechin is a small chemical (see picture) but when it gets oxidized, it can form a dimer.  Dimers can be oxidized to form trimers, and so on.  As the chemical polymerizes, it has a harder time binding to the proteins in spit.  So as the wine ages, it seems “softer” or more mellow.  Other phenols and flavinoids can also be oxidized and combine to form very exotic chemicals that cause changes in the character of the flavor (more chocolate, less berry, hint of woodsmoke, etc).  I can’t even begin to comprehend how many different combinations of chemicals you could create inside that bottle.  You might be wondering how this happens -- I said that oxidation was bad (vinegar) and oxygen levels are low during fermentation.  Where does this tiny bit of oxygen come from?  The cork.  The OTR (oxygen transmission rate) of the cork results in micro—oxygenation of the wine.  These magic tannins are basically buffering the wine from a slow oxygen leak, protecting it from the bad types of oxidation that lead to enological disaster and creating tasty flavinoids in the process.  The more tannins in the wine, the longer it can be stored and potentially the better it gets.  Wine is truly an amazing witches’ brew! 

  So, is winemaking driven by science or magic?  If it’s science, is sure isn’t governed by classical mechanics.  There is little to no predictive power and the system is far too complex to control.  Even comparing it to quantum mechanics is a stretch.  Every batch that is set up will come out different because at the end, the distribution of tannins (type and concentration) cannot be predicted.  It will taste generally like a cabernet, but the specific taste will be different from batch to batch and sometimes even bottle to bottle.   Since there are multiple biochemical pathways involved, each with interdependent feedback loops, and the final output is so exquisitely dependent on the initial conditions, I wonder if the process is actually chaotic.  What if winemaking was described by something like a Lorenz attractor?  These non-linear dynamical systems are characterized by being globally deterministic (it tastes like a cab) but locally unpredictable (I taste bell peppers!).  The weather is a good example as is the stock market.  This means that good winemaking will likely come from empirical observations, intuition, and a little luck.  I do wonder if someday scientists will understand which tannins correspond to what taste or sensation.  One could then make synthetic wines using a simplistic fermentation process followed by the addition of supplemental tannins to create the right body.  But somehow, I don’t think that scientists will ever be able to, um, convincingly fake it.

The final bottle of the night was a 2009 Rockpile Rocky Ridge Zinfandel – “a zin for cab lovers”.  The description said it was “the perfect yin-yang of dark berries and savory spices” with “spectacular structure, layered complexity, and balance”.  Blah, blah… whatever.  This stuff was orgasmic. I really didn’t care what the hell was in there.   If that’s what a really good Zinfandel tastes like, I might be a believer.  So I poured myself another glass, let it open up a bit, and chalked one up for magic.