What is lees or sediment in wine?

What is lees in wine?

Dregs, also referred to as sediment, sediment or deposit, are the residual solids in wine after fermentation or after a certain aging time. Suppose we take an unfiltered red wine in the bottle as an example. In it there are various particles ranging from large yeast cells and tartaric acid crystals to tiny components such as bacteria, tannins, dyes and proteins, with sizes between five and 10 microns (0.005 to 0.01 millimeters). There are about half a million of these particles in a liter of wine.

Often we see the solid particles, or lees, appear in the bottom of the bottle when it has lain for a while after purchase. During this time, first the yeast cells and bacteria have sunk to the bottom, followed by the tartaric acid crystals. Finally, some of the coloring agents, the anthocyanins, broke down and settled, while another part of the anthocyanins formed larger molecules or attached themselves to the tannins. The result of all this is described as lees, sediment or sediment.

In red wines that have aged for a long time, the aforementioned sediment formation is related to the change in wine color. From vivid ruby red, most wines evolve to a kind of terracotta red, followed by the addition of an orange hue and eventually the wines even turn amber. This change is caused by tannins that, over time, clump together and bind to the pigment or anthocyanin in the wine, affecting its color. If a bottle has lain flat during the aging process, the sediment can be found in the bottom of the bottle. In very old bottles, the sediment can even fill half a wine glass. In that case, we recommend carefully decanting the wine and leaving the bottle upright in a cool place for a day so that the sediment collects at the bottom of the bottle.

Sediment, however, is not necessarily related to tannins clumping with anthocyanin in wine over time. Instead, sediment can vary enormously in shape and occurs in young and old wines, ranging from white, orange, rosé and red. Although lees is not always visually appealing, it is by no means an immediate concern. Certainly not in natural wines, where filtering wines is generally out of the question. Precisely because of the choice not to filter, or clarify, sediment often occurs at a young age in natural wines. However, the rate at which lees appears in a wine also depends on the specific grape variety. For example, a Chardonnay coming from Burgundy is known to be subtle in texture, while a young Barbera may soon show significant lees.

And while not filtering can thus lead to cloudy wine, it certainly does not adversely affect the quality of the wine itself. Indeed, natural wine producers very deliberately choose unfiltered wines in order to allow the full flavor characteristics and aromas to speak for themselves.