In the Winery - Art versus Science in the Wine Lab


How wine is made is a mystery to many people.  When looking into our processing facility, we often hear comments like "that's where the magic happens."  In reality, wine processing is more like "where the science happens."  But to my dismay, it's not all science.  There is art involved in wine-making, and as a mathematician by training, art is not my forte.  Thankfully, I am able to apply science right up to the final stages of processing, but that's where for me, things get a little dicey.  Let's take a look at two white wines which will be released this summer...Riesling and Summer see how they are similar and how they are different.

Frontenac gris grapes at peak ripeness

Grapes harvested at the peak of ripeness are the perfect fruit from which to make wine.  There is enough natural sugar and enough water that neither of these need to be added.  Pitch some wine yeast along with some nutrients, and voila...fermentation produces wine from grape juice.  In the wine lab, three of the components we test in ripe grapes are pH, titratable acidity, and sugar level.  To a winemaker, sugar level is not an indication of sweet wine vs dry wine.  Sugar level is all about potential alcohol.  Yeast converts sugar to ethanol, and a large percentage of sugar is needed to produce ethanol in the 12-14% range.  This is generally an easy number to hit provided grapes are harvested when they are ripe.

Titratable acidity and pH, however, are more of a moving target.  As mentioned above, we are currently putting the finishing touches on our Riesling and Summer White wines.  The grapes that produce these wines have some things very much in common, like sugar level.  But their pH and acidity levels differ dramatically.  Because our Riesling grapes tend to have a moderate pH and low acidity, we can produce a dry or semi-dry wine from them.  Why is this?  Because a dry wine that is high in acidity will taste sour.  Wines that are high in acidity need some residual sugar for balance.  A crisp finish is nice in a drier wine, but a tart, sour finish is not.  Since our Riesling tends to have low acidity, we are comfortable keeping this wine on the drier side.

SWhite and Riesling for blog.jpg

The grapes for Summer White, however, tend to have much higher acidity and very low pH.  The grapes varieties in Summer White are Brianna and Frontenac Gris, both grown right here at River Bend.  Our cool climate produces grapes with higher acidity than say, grapes from the Napa Valley.  It is because of this that wines made from cool climate grapes are often sweeter.  The higher acidity must be balanced with residual sugar so the wine is not too tart but has a pleasant, fruity finish.  The challenge...and the just how sweet is perfectly sweet for a given amount of acidity.  Too much residual sugar is just as bad as too little, making the wine flat or cloying.  We strive for a moderate level of sweetness that still leaves a clean finish on the palette.

For me, this is the tricky part, and we make this decision based solely on taste (art) and not on numbers (science).  It sounds pretty fun to taste wine all day to get the sweetness level just right, doesn't it?  We actually agonize over this process, because we want all of our wines to be approachable and balanced.  At the end of the day, the palette of our customer is the final judge on whether or not we hit our mark.  

Once we finish up in the wine lab, we'll be heading back outside to check on the vineyard.  Bud break has occurred, and we are about to see tiny little flowers and grape clusters emerging.  Exciting!  Do stay tuned.