Has Wine Changed Over the Years? Oh Yeah

The graph below, from the American Association of Wine Economists, has been making the rounds recently. It shows in "graphic" detail the biggest change in wine over that past few decades. That is, the amount of sugar in the harvested grapes, which translates into alcohol in the wine.

Click on image to enlarge for readability

Degrees Brix (pronounced bricks)

Brix measures the sugar content in fruit. If you remember HS chemistry, assuming you were unlucky enough to take it, Brix measures soluble solids in a liquid. Soluble solids mean they're dissolved in water. As Brix on the harvested grapes goes up, so does the alcohol level of the wine. Multiplying the Brix by .55 will give you the approximate final alcohol level of a dry wine.

Grape harvest

So why don't they just harvest the grapes earlier when there's less sugar content? Brix is only one measurement used to determine perfect ripeness. In the old days it was based on grapes looking full and juicy, the color of the grape seed, and the taste of the grapes. Now there are technical measurements added to that looking at pH and acidity to get a proper balance.

If you harvest strictly on Brix you might get the level of alcohol you want, but with an acid level that is too high, meaning you'll get an acidic, bitter wine. There's also phenolic ripeness which is about the development of flavors and aromas. So there are several things the winemaker wants to balance, and sometimes there's a trade-off.

One telling sign that something as changed is the California grape harvest has gotten earlier and earlier, by several weeks.

Why has this increase in grape sugar happened?

There isn't an easy single answer. People look at things that have changed and theorize on why each one caused the change. I expect it's a combination of some or all of these.

• Grape rootstock - Grape vines are planted on various rootstocks and each has its reasons for use. Phylloxera, a bug that damages the roots, wiped out most vines in the late 19th century. The savior was a North American rootstock called AXR1 that was resistant. All over the world vines were replanted on AXR1. This worked for almost a hundred years until Phylloxera mutated and again spread through vineyards. Once again, replanting was done and now many different rootstocks are used. So the theory is that AXR1 slowed down sugar development, whereas the new ones allow faster sugar progression.
  
  
• Trellising - There are various methods of growing grapes on wires or occasionally just as a round bush with no wires. Each method has pros and cons, and it seems that people have jumped on different methods as they get trendy. If you look at California vineyards you can guess the approximate age of a vine by how it's grown. Head pruned (no trellis wires) means it was planted by the mid 20th century. Various forms of what's called cordon pruning seemed popular in the 1970s and '80s. Cordon is sending main branches along a wire, usually one, two, or four branches from each vine. In the 1990s Vertical Shoot Positioning (VSP) became the standard. VSP exposes the clusters to plenty of sun, making the vines easy to prune and the clusters easy to harvest. That full exposure could be the problem with too much sun and heat.
  A previous post on grape trellising and climate change.
  
  
• Climate change - Most farmers are worried about warmer weather. Wine grapes are very susceptible to any change in the climate. This is why you see Cabernet growing in one microclimate and Pinot Noir in another, slightly cooler region. Increased heat means increased sugar content. Grape farmers and winemakers are trying to figure out what they can do to prepare for the coming decades of what might be some crazy weather.
  
  
• Parker points - Robert Parker was the most followed American wine writer at one time. If Parker gave a wine lots of points it sold out quickly. He loved the '97 vintage from Napa. It was an abnormally warm year, wines came out ripe, often described as plush. Even though some winemakers weren't sure about that vintage initially, once they hit the market they were all the rage. Hmm, we need more wines like that.
  
  

Are there any theories I've missed?

VSP trellis with full sun exposure

The difference in today's wine vs. yesterday's

This is a personal perspective, a broad generalization, and related to alcohol levels.

The old days saw leaner wines vs. today's full-bodied ones. Many reds had mouth-drying tannins when young and required a few years to become what they should be. Today most wines are at or near a good drinking stage. This works well as almost all wines are consumed within a few days of purchase. Today's wines are softer and fruit-forward. IMO many current wines are missing a lot of complexity and finesse found in wines from the old days. Today's wines are easier for the new wine consumer to enjoy -- that sense of sweetness instead of mouth-drying tannins.

Disclaimer: I don't have grape-growing or winemaking experience. I believe the technical detail here is correct. This post did get a little geeky, huh?