Have you ever poured yourself a nice glass of wine, perhaps even a bottle from one of your wine of the month club shipments, just to notice something gritty or sand-like has suddenly invaded your wine and is now swishing around unpleasantly in your mouth? That would be the wine sediment.
So what is sediment?
Sediment is a byproduct of winemaking that usually settles to the bottom of your glass, and it can form during the fermentation process or while a wine matures in a bottle. Sediment is completely natural and not harmful, with most of it made up of bits of seeds, grape skin, and crystal-like tartrates. Some winemakers fine or filter their wines to remove these solids, while others prefer to leave it, believing it gives the wine more character and complexity. If its presence bothers you, simply decant or aerate the wine before serving.
If you’re an avid wine drinker like the majority of us in our office, or if you receive any of our wine club shipments, you’ve experienced this phenomenon at least a handful of times. If you’ve only recently encountered sediment in your glass, don’t worry, as we stated above, there is nothing wrong with your wine! No matter the amount of sediment, it is a completely natural occurrence in red and white wine, and can actually be a sign that you’ve gotten yourself a high quality bottle! But we’ll get to that.
Technically speaking, sediment is also called “wine dregs” - but before you judge your bottle of wine by this unfortunate double-entendre, sediment can also be referred to as ‘wine crystals’ or ‘wine diamonds’. Sounds a bit better than ‘dregs’, right?
Sediment has two forms: tartrate and colloids
Tartrates are the larger ‘crystals’ you may find on the end of a cork or clinging to the sides of the bottle or your wine glass. These jagged, burgundy-colored, diamond-like structures are formed when tartaric acid (a natural element in grapes) binds with potassium while exposed to cold conditions. Under these circumstances they form beautiful crystalline salt formations.
Colloids on the other hand, are the smaller and finer-grained sediment which are made of polysaccharides and protein, or can simply be leftover remnants of grape skins, stems or seeds. And yes, both forms of sediment are harmless!
What are Polysaccharides?
Polysaccharides, for those of us who somehow missed that day of chemistry class, are carbohydrates made up of multiple sugar molecules bonded together. They also contribute to the overall mouthfeel of a wine.
But we’re getting off track.
Although sediment is usually more prevalent in red wines, they can occur in white wines too! Winemakers will sometimes intentionally leave tartaric sediment in the barrel while the wine ages. This is called ‘sur lie’ aging, which translates to ‘on the lees’ and can supplement and intensify flavor in the finished wine. You may also see this term used in some of the tasting notes for wines you’ve received from any of our six wine of the wonth clubs.
Lees in red wines vs. crystals in white wines
Two types of sediments exist, lees and tartrate crystals, also known as “wine diamonds”. A major difference between the two is which wine they occur in and why they are there. Lees is a common phenomenon of red wine, whereas “wine diamonds” are a creation of white wines.
As you may have suspected, winemakers crush whole grapes to make their red wines. Therefore, along with the juice, the skin, pulp, and seeds are all a part of the creation. Since the skins are what give a red wine most of its color, aroma, and texture, it often has more grape particles dissolved in it. A new red wine is full of these bits and pieces, but most of the sediment falls out as the wine ages and ferments or it sinks to the bottom. When the winemakers pump the wine, the lees are removed, but sometimes, microscopic pieces remain. After many months or years in the bottle, a fine sediment accumulation of lees forms at the bottom of the liquid, and can stand as evidence of a great, well-aged red wine.
White wines tend to have less sediment for a few reasons. The first being that white wines, only use the juice and pulp, not necessarily the skin or seeds like red wines do. Next, wineries tend to stabilize their white and Rosé wines, but not their reds, meaning the whites are less often aged on their lees. Another reason is that more white wines and Rosé wines are served chilled, and refrigeration causes the formation of the tartrate crystals in the bottle. Taking a quick trip back to our childhood chemistry class, refrigeration causes this because heat helps solid substances dissolve in fluid, while the cold can return them back to a solid state or in this case a crystal form.
Finally, these crystals, diamonds and gritty-goodness can indicate you have a high quality bottle of wine! The best winemakers know that, oftentimes, less is more when it comes to intervening with methods like filtering. When wines are filtered, it not only gets rid of the sediment but it also strips the wine of quality features such as mouthfeel and even palate flavor expression. (See our Wine Glossary for further explanations of wine terms!)
So the next time you see wine sediment settle to the bottom of your glass, rejoice! You could be in for a real treat.