Every Grape is Different — Notes from a Vineyard Conference

February 5, 2012 | By | Reply More

 The Virginia Vineyards Association brings together commercial grape growers, hobbyists and others with an interest in viticulture, and its efforts to promote cooperation and the exchange of information  is one of the reasons that the Commonwealth’s wine gets better every year.  I believe, and I think most of the growers who participated in the association’s technical meeting in Charlottesville last week would agree, that the reputation of Virginia wine is influenced by every bottle that’s sold.  If someone has a bad experience the first time they taste a Virginia wine, they may never try another.  So all of us have a vested interest in doing what we can to help each other make the best wine possible. 

Seven glasses ready for tasting. The bottle of “SanTasti” is a palate cleanser.

  Another reason for the success of the Virginia wine industry is the work that’s being done at Virginia Tech by folks like Tony Wolf, Bruce Zoecklein, and Mizuho Nita, all of whom played major roles at the meeting.  Tony Wolf’s book, Wine Grape Production Guide for Eastern North America, has become our bible as we move toward planting a small hobby vineyard, and Mizuho Nita’s blog is the indispensible guide to grape disease management.  

  However, this was my first encounter with Dr. Zoecklein, and I’m hopeful now that it won’t be my last.  Dr. Zoecklein has written the book (actually, at least four books and too many articles to count) on wine chemistry, and he manages to make the chemistry both accessible and practical for people like me.  And since this was a class on “Sensory Evaluation for Grape Growers,” he taught the class through the tastes and aromas of seven separate wines, which we tasted blind throughout the class.

Dr. Bruce Zoecklein after an afternoon-long lecture on Sensory Evaluation for Grape Growers

The seven wines each exhibited distinctly different characteristics, and as Dr. Zoecklein worked through his lecture, we would periodically taste one of the seven, always in comparison with another wine, which most often was glass 1, an inexpensive, but well-made wine that served as the control glass.  It’s one thing to talk about the effect of astringency on a wine, but quite another to taste it, and the tastings drove his points home very effectively.  (And to make it more complicated, astringency is not a true taste, but more of a sensation.  And yet, it is clearly part of what we perceive as taste when we drink tannic reds.)

  I won’t recount the entire lecture, which was focused on grape chemistry, but I’d like to offer a few nuggets of information that surprised me.  Actually, what I liked best about the seminar is that it challenged a lot of ideas that I thought I understood, and reminded me just how complicated each aspect of viticulture really is.

  For example, like many, I’ve always thought of brix as a key – perhaps the key – measure of a grape’s readiness for harvest and the quality of the wine that will be made from it.  And that’s true, as far as it goes.  But as Dr. Zocklein noted, we emphasize brix in part because it is so easy to measure.  (Trust me, almost anyone can wander through a vineyard with a refractometer and test brix.)

  And while brix is a measure of potential alcohol, the key word is “potential.”  We frequently think of the relationship between brix and alcohol as .55, so that a brix of 22 will translate into alcohol of 12.1, but Dr. Zoecklein explained that there is considerable variation in the percent of alcohol that comes from the measure of brix, and the conversion rate can actually vary from .52 to .62.  That’s because alcohol is determined by the ratio of soluble solids to liquid, and not all the solids in the grape are sugar, which is what brix measures.

  Moreover, there is considerable variability from vine to vine, even in the best vineyards, due to asynchronous ripening of grapes.  “Each berry matures separately, but they are all harvested together,” Dr. Zoecklein said.  So, if you harvest at a certain brix, there will be a wide variation among the grapes that are picked.

You can see that if you walk through a vineyard, post-veraison though to the harvest.  Even within a cluster, it will be obvious that some grapes have ripened more quickly than others, and the ripest grapes will have very different sugar levels from the less ripe.  Each grape is different, and that’s one of the reasons sorting tables are so important.

Again, while brix is the easiest thing to measure, it’s far from being the only important factor in the quality of wine from a particular harvest.  Acidity, pH, phenolic compounds (particularly tannins and anthocyanins), the health of the grapes (“a little rot goes a long way” toward ruining wine, as Dr. Zoecklein put it), are among the many factors that contribute, and Dr. Zoecklein provided quite a good introduction to the whole subject over some three and a half hours Thursday afternoon.

It was noteworthy that this lecture was aimed at grape farmers.  As the old saying goes, good wine is made in the vineyard, and so it’s of obvious importance for the vineyard manager to keep his eye on the end-product, the wine, throughout the growing season.  And for me, on this first day of the technical meeting, the lecture was another reminder of how much there is to learn about the whole field of viticulture and enology.

There were lots of other reminders over the next two days, which I’ll be discussing in posts later this week.  Stay tuned for more notes from the Virginia Vineyard Association’s 2012 technical meeting.

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Category: All Posts, Viticulture

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