What is a wine's “dry extract”?

Hello there! I'm Dr. Vinifera, but you can call me Vinny. Ask me your toughest wine questions, from the fine points of etiquette to the science of winemaking. And don't worry, I'm no wine snob—you can also ask me those "dumb questions" you're too embarrased to ask your wine geek friends! I hope you find my answers educational, empowering and even amusing. And don't forget to check out my most asked questions and my full archives for all my Q&A classics.
Dear Dr. Vinny,
I saw a review of a wine that said it had a “whopping 37 grams per liter of dry extract.” Did they mean suspended solids in the wine?
—Olympic Wine Brokers, Poulsbo, Wash.
Dear OWB,
You’re on the right track. Dry extract refers to the solid part of the wine—the powdery stuff that would be left if you removed all the water and alcohol from a wine (presumably, after playing with a centrifuge).
This is an extremely technical term, but it’s pretty easy to see how dry extract relates to the body of a wine: The more dry extract, the heavier, thicker or bigger the wine. Generally, the solids of a white wine lie around 15 to 20 grams per liter, while red wines are closer to 20 to 30 grams per liter. So, yeah, 37 grams per liter of dry extract is pretty “whopping.”
Or, more like “big whoop.” I don’t know many winemakers who look at dry extract (thought it’s required analysis for export to some countries). I’ve heard the term used to explain the popularity of riper wines, because higher dry extract can balance or even hide higher sugar levels in wine. But for the most part, it’s not a term that's very useful to wine lovers.
—Dr. Vinny