A Comparison of Brix and Alcohol from 1974 to 2006 ~ You’re going to be surprised!

A very interesting thing happened on the way to creating a spread sheet for a Foppiano Vineyards Petite Sirah vertical.

I gathered all this technical info… The kind of details that cause wine writers to experience spasmodic ecstasy each time they evaluate wine… TA, pH, alcohol, etc.

I understand how this theoretical gathering is part and parcel of the wine evaluation process for writers. Personally, I lean toward a more practical evaluation. When I taste wine, I instantly know if it’s in balance just by its flavor. I have a very sensitive palate and nose. For instance, if a bottle of wine is opened across the room, I can instantly pick up any TCA. I don’t have to swirl, sniff, or taste… (This comes from living most of my life with damp New England basements.)

Yesterday, I didn’t need a tech sheet when tasting a Zin that was in question. I tasted the wine, and I spit it out a lot faster than it went in, without looking at anything. Relying on my own instincts (for me) is very powerful. (I’ve also taken so many university units for wine sales and marketing, including oenology, viticulture, wine components et al — doing so much paperwork — that maybe I’ve just fallen into, “Just let me enjoy the wine.” Who knows?)

Technical sheets are definitely a security blanket, though, so we PR types religiously gather the data, and make sure that when samples go out, there’s accompanying support material.

So, here I was… putting a spread sheet together and there before my very eyes… the evidence.

In recent years, brix levels have begun to climb; but, not by leaps and bounds as anyone might expect from all the hoopla that’s going on. It’s been growing by almost negligible amounts, and yet these slight increases are making this a very “hot” topic.

Now that I visually produced Winemaker Bill Regan’s statistics, however, this whole hoopla thing seems disproportionately out of proportion, and in need of further explanation and evaluation, because the left side of my brain was now really curious.

Thinking out loud last week, I questioned, “I wonder how this could be… Going from a 23 degree brix to a 24 degree brix, but alcohol’s climbing by nearly two to three percent?” The person I was with at the time said, “It’s due to all this cluster thinning. That makes the flavor or grapes more intense; therefore, they have more alcohol.”

Okay, that didn’t do it for me. When I studied oenology, Winemaker Pat Henderson of Valley of the Moon, didn’t teach that one at all… Neither did my viticulture professor. I was polite and didn’t let on that that answer didn’t seem scientifically possible. I was still processing the possibility. Cluster thinning doesn’t logically translate over to sugar levels. Sugar levels come from yeast eating sugar in the juice and converting that over to alcohol… And, that seems to be nearly a 2 to 1 ratio… Hence, 13.5% alcohol comes from a 24 degree brix.

Harold Baer of Colorado Wine News, who got a vertical to evaluate, commented, “Jo, Many thanks. Fascinating fact sheet. Did you notice how the alcohols have increased even when the brix has not?”

So, I asked Bill about this, because it’s his wine, after all… Right to the source.

Bill had an interesting answer, and one I would never have considered (I think I’m ready for Enology 181). According to Bill, in recent years, yeasts have become more efficient; so, when they used to covert sugar to alcohol by a 0.57% conversion, they’re now doing it at a 0.6% rate.

Yeast is now able to convert sugar to alcohol in a bone dry way, too. According to Bill, that wasn’t always the case, and you’d have a bit of residual sugar you’d have to deal with as a winemaker. Winemakers are still learning to adapt to this new phenomenon. Aha! Sounds like a great topic for the 2008 Petite Sirah Symposium: “How to harness your alcohol from more efficient yeast.”

This was an answer that satisfied me, and took global warming out of the equation, for now.

If you’re a winemaker, feel free to continue to enlighten us, as inquiring minds really want to know… Bubble, bubble, toil and trouble!

Here’s the chart…

4 Responses to “A Comparison of Brix and Alcohol from 1974 to 2006 ~ You’re going to be surprised!”

  1. Morgan says:

    “yeah. I think the answer for yeast efficiency is something

  2. Vance Booher says:

    Fascinating and timely in view of the seemingly unending Hangtime debate. It does beg the question though about what is happening to those grapes harvested at even higher sugar levels. Those efficient yeasts likely explain some the 16-17% monsters out the

  3. Mark says:

    Why not look at a winery that still uses native yeasts as a way to test this theory. Doesn’t Ravenswood still use native yeast for their fermentation? Perhaps a similar vertical comparison would provode some insights.

  4. Mike says:

    “If its the yeast that is responsible for what you have observed then the question that needs an answer is when was the change made to these “”more efficient”” yeast strains? Or was it another gradual process? I was under the impression that one of the expla”