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What causes sediment in wine?

15/02/2023 The tasting , Winemaking

You’re likely to have occasionally come across some sediment at the bottom of the bottle or in your glass. Don’t worry, this doesn’t mean it’s a defective or poor quality wine. These are just wine sediments. And they are pretty normal. If you don’t like the look of them, there are ways to stop them ending up in your glass.

What are they?

Sediments are just residual yeasts and other particles that fall to the bottom of the barrel after fermentation and aging. In winemaking language they are also known as sludge, sediment, tartar or lees and define all the solid parts that remain in the wine during aging. That is why they have nothing to do with the quality of the wine, nor with the way it is stored. They are a very common consequence of the oxidation, fermentation and maturation processes, which is why they are often found especially in wines that have been aged for a long time.

In common practice, once the wine has been made, it is transferred to other containers, leaving behind these types of sediments. However, many wines are left to age on their lees so that the wine takes on more aromas, flavours and body. If the wine also undergoes batonnage, which involves stirring these floating lees with a stick to increase all their properties, the chances of finding sediment in the wine increase considerably.

However, wine doesn’t always contain sediments. It is usually a matter of time before the solid particles from the fermentation process drop to the bottom of the tank and are removed by racking. However, young wines that have to be released for sale quickly don’t leave as much time for this to happen, and they are not always completely free of suspended substances.  

To avoid them and make a completely clear wine, during the winemaking process many winemakers carry out clarification and filtration to remove natural sediments. Clarification uses natural products that accelerate the cleaning process, like egg whites, milk casein, bentonite, peas, potatoes or wheat. These are binding products that are heavier and therefore fall to the bottom in the form of a filter, dragging the solid particles that are suspended.

Another thing the winery can do to leave the wine completely clean and free from impurities, is filtration. This happens after racking and clarification and is a process that separates the solid elements of the wine through a porous medium, like a fossil sand system, prefabricated plates or membranes. However, we must be very careful here, as we run the risk of removing some of the wine’s personality and detracting from its intensity, both in terms of colour and texture or flavour. However, wine is still a living thing and, even if it has been clarified and filtered, it may develop some particles that fall to the bottom of the bottle. These sediments form as the wine develops in the bottle and don’t negatively affect either the aroma or the taste of the wine.

Why are they becoming more and more frequent?

Although consumers were used to enjoying a clear wine without any sediment, the presence of lees is becoming more and more common. It suggests that the winemaking process was calm, respectful and artisan and that the personality of the wine has not been altered at any point.

The truth is that in an increasingly competitive market, more and more winemakers want to convey a unique personality in their wines. To achieve this, it is essential to use high quality grapes and then use the most respectful winemaking process that guarantees the preservation of the fruit’s original characteristics. This is why many prefer to avoid clarification and filtering that could affect the final result, thus inevitably leaving these famous lees in the wine.

How can you avoid them?

Even if we know that a wine with lees doesn’t pose any threat, the truth is that it is not particularly pleasant to find them in your glass or, even worse, in your mouth. To avoid this, you can follow a series of steps that will likely avoid them.

1º Before opening the bottle, it is important not to move it. Let it sit upright for a few hours so that the sediments fall to the bottom by gravity.

2º Once the bottle is opened, decant the wine slowly into a decanter in front of a light source so you can see the sediment sitting at the bottom of the bottle.

3º When you see that the wine starts becoming cloudy towards end of the bottle, stop decanting and leave the sediment inside the bottle.

4º Likewise, once the wine is in the decanter, it should be poured slowly into the glass, avoiding any sediments that might have crept in during the decanting process.

You get the idea! While some people prefer wines with sediments because of their taste, aroma and texture, others want to enjoy a clean and clear glass. Decanted or not, the important thing is to enjoy wine as you like it. So you decide how to serve it.