By definition, etymology and inclination, sediment is just stuff that settles. Most often, it refers to solid particles suspended in and carried along by a fluid, before they’re drawn inexorably downward by gravity to collect in the lowest place they can find. River beds and the ocean floor are rich in sediments both mineral and biological.
You might say that sediment has a knack (not unlike a certain celebrated fictional detective we know) for getting to the bottom of things. When the bottom in question belongs to a wine bottle, it’s a sure sign of … uh, what exactly?
Because we normally encounter wine only at the end of its production cycle, it’s easy to forget that a very large part of that process involves separating the solid bits of fruit from the juice. This means not just grape flesh or pulp, but seeds, stems and skins. In the making of conventional white wines, this separation happens right at the beginning of the process as fruit is gently pressed to extract juice which is then fermented apart from any contact with grape solids.
In red wine production, berries are crushed and fermentation occurs in a vat where solids infuse the juice with all the wonderful, naturally-occurring organic chemicals that make red wine red and lovely. When the fermentation is complete, or nearly so, the whole business goes into a press with a view to wringing out whatever goodness remains. The resulting solid mass — the gross lees — is then trucked off to the compost heap (or grappa factory).
But we’re still far from dealing with clean, salable wine. With no more sugar to consume, yeasts that labored mightily to accomplish fermentation have now given up the ghost, their myriad tiny bodies collected in a thick, creamy layer of sediment — the fine lees — at the vat bottom.
At this point, the young wine will typically be drawn off into another tank or barrel, where the process will continue until most of the remaining solid matter has precipitated. We say most, because, in fact, much of what makes wine flavorful, aromatic and texturally pleasing is what’s called dry extract — the sum of solid matter like proteins, pigments, tannins and pectins — existing in in the form of particles light enough to remain in suspension.
Even though we don’t experience them as solid matter, they’re just that.
So what about that sediment in the heel of your bottle? Vintners may take a final step of filtering their wine to remove fine particulate, but even this doesn’t guarantee that your wine will not eventually throw off a bit of schmutz. That’s because molecules of dry extract have a habit of polymerizing (glomming together) and eventually becoming so heavy that they fall out of solution. It’s the reason years in bottle have the effect of mellowing wine. Along with other solid matter molecules, most of the tannins will have been collected as sediment.
A bit of fine debris in your wine isn’t evidence of a felony, or even a misdemeanor. On the contrary, it might just be a reliable character witness testifying to the fact that your wine was made in the good old fashioned way, with plenty of the stuff that makes a sound, flavorful wine what it is.
Another case closed, Watson. Now, about that hound that’s been seen around the Baskerville estate …