Nearly all sediment found in wine is naturally occurring and is in no way harmful.
In fact, many wine pros and enthusiasts like to see a bit of sediment in their wines, particularly red wines that have been in bottles for more than five years. Sediment in wine can indicate a wine that has not been heavily filtered or otherwise processed.
Sediment is a part of winemaking. At the bottom of every fermenter, you will find a sediment layer comprising dead yeast cells, grape parts, tartrates, pigment polymers, and other discharged solids.
When wine ages in a cask, many of these identical particles fall out of the wine over time and are separated from the clear wine before bottling. Winemakers often perform a process known as “racking” that involves siphoning wine from one carboy to another, leaving sediment behind. A wine may be racked three times or more to aid in clarity prior to bottling.
Once a wine is in the bottle, it may develop fine particles that settle over time as the wine ages (even when the wine is brilliantly clear at bottling). You will rarely see sediment in wines younger than 5 years, whereas it is pretty standard in red wines aged 10 years or older.
Sediments found in wine bottles include polysaccharides, proteins, pigment, and tartrates (potassium bitartrate crystals). Tartrates, when collected from tanks and barrels at the winery, can be sold and processed into cream of tartar, a common kitchen item known to almost any baker.
Keep Sediment in Wine out of Your Glass
While sediment in your wine is totally harmless, few people want a mouthful of chunkies while sipping their wine. You can avoid most sediment by carefully decanting the wine and leaving most of the solids in the bottle. Decanting your wine has numerous benifits but the most commonly understood benefit is separating clear wine from sediment. It is helpful to stand the bottle for at least 24 hours (three days is better) before decanting as this concentrates the sediment at the bottom of the bottle.