We’ve had a few people email us to ask about the solids they find in bottles of wine. Some are concerned and some are merely curious, but we thought we’d take a minute to explain what sediment is and why it can counterintuitively be a good thing to find. The short answer is sediments are a natural byproduct of winemaking and can indicate a wine that is less manipulated by humans.
What is it (and is it safe)?
Sediment comes in mainly two forms, one (particulate fall out) is more common in reds, the other (tartrate crystals) show up more often in whites. Both are natural byproducts of wines with minimal human manipulation, and are completely safe. In fact, on top of being harmless, they are a good sign you are drinking a wine that has not been put through unnecessary filtrations just for the sake of aesthetics. They help remove the particles early, before they naturally fall out, but can often take away from the full expression of a wine. Though you may fall in the pulp-free contingent when it comes to orange juice, you can think of the unfiltered wines as farm stand-style products compared to more highly processed ones.
That being said, while these most common reasons for the tiny solids in your wine are not a direct indication of a mishandled bottle, there are a few instances where a cloudy or chunky wine is indicative of a flaw. Cloudiness in a wine that is not deliberately unfiltered might be a sign of spoilage. A quick smell and taste will tell you right away.
How does it get there?
If we go a little deeper into the science of the wine making and aging process, it’s easier to understand where the sediment actually comes from. Particulate fall out, most common in reds and increasingly found in white wines with extended skin contact (i.e. orange wines), is a simple result of time. The first stage of solids separating from solution happens during and right after fermentation. As the wine goes through many (natural) chemical conversions, the solid material from dead yeasts, grape pulp, skins, stems and seeds will fall to the bottom of the barrel. At this stage the winemaker may choose to implement aggressive filtering that will remove these larger particles and preempt some of the later fallouts. There is also a gentler option called racking that can be done before the wine is bottled. In this process, the wine is left to rest as long as necessary for the majority of the particles to settle to the bottom of the fermentation vessel. The clear wine is then siphoned from the top until the wine being siphoned is no longer clear. This process leaves many of the finer grains in the solution which will help the wine develop nuance and complexity as it ages.
As a wine rests in the bottle, these tiny particles of skins and stems, etc. will precipitate out of the solution, along with tannins and pigments that had been suspended in the younger wine. This is what you may end up finding in a great bottle with some age. The fall out will be more dramatic in grape varietals that are very pigmented or have thick skins and ones that are very tannic.
The second sediment typically encountered is tartrate crystals, also known as wine diamonds. They can be alarming at first, because they look a lot like tiny shards of glass. They are actually crystalline salt formations that are created when the tartaric acid, a natural and important element in wine grapes, binds with potassium (also found naturally in wine). This reaction is triggered by very low temperatures, i.e., refrigeration and can be preempted before bottling by a process called cold stabilization where wine are intentionally brought to near freezing temperatures until the crystals fall out. Tartrate crystals are often harvested and are ground up to be sold as Cream of Tartar. This process saves the consumer a surprise, but can also make the wine more susceptible to oxidation and change the natural acidity. The reason reds don’t have this problem often is simply that they are not often stored at very low temperatures.
What can you do about it?
Sediment is so common in the wine drinking experience that decanters are a standard accessory in many restaurants and home bars. You can google best practices for decanting, but just think of it like a mini version of racking. Your goal is to remove the clear wine while disturbing the settled sediment as little as possible and leaving it in the bottle.
If you don’t own a decanter, or didn’t have enough heads up to let a bottle rest, then pour carefully and leave whatever does make it into your glass at the bottom, like tea leaves. This is the finest form of racking. Also, don’t fret too much if you end up with a mouthful of sediment, though you probably won’t enjoy swallowing it, it is absolutely harmless and will remind you that you just had an excellent bottle of wine.