As an experienced sommelier and brewer, I can provide you with a detailed answer to your question about what can be filtered out of wine. When it comes to filtration, the main aim is to remove sediment, which is typically composed of yeast cells, unstable tartaric acid, and tannins. Sediment can give a cloudy appearance to the wine and affect its taste and texture, so filtration is an important step in the winemaking process.
To achieve effective filtration, it is recommended to chill the wine before filtering. This helps to enhance the filtration process and improve its efficacy. If possible, it is ideal to allow the wine to sit in a spare fridge or outdoors at a temperature of around 45 degrees Fahrenheit for about a week before proceeding with filtration.
The primary culprits that contribute to sediment in wine are yeast cells. During fermentation, yeast consumes sugars in the grape juice and converts them into alcohol. After fermentation is complete, some yeast cells may still be present in the wine. These yeast cells can settle at the bottom of the bottle over time, leading to sediment formation. Filtration helps to remove these yeast cells and clarify the wine.
Another component that can contribute to sediment is unstable tartaric acid. Tartaric acid is a natural component found in grapes and is responsible for the tartness in wine. However, under certain conditions, tartaric acid can become unstable and form crystals, which can settle as sediment. Filtration can effectively remove these tartaric acid crystals, improving the visual clarity of the wine.
Tannins, which are natural compounds found in grape skins, seeds, and stems, can also contribute to sediment formation. Tannins give structure and texture to the wine, but excessive amounts can lead to astringency and bitterness. Filtration can help to remove excess tannins, resulting in a smoother and more balanced wine.
In my personal experience as a winemaker, I have found that filtration is a crucial step in achieving the desired clarity and stability in wines. By removing sediment, the wine appears visually appealing and is free from any unwanted particles that may affect its flavor and mouthfeel.
To summarize, filtration in winemaking aims to remove sediment, primarily consisting of yeast cells, unstable tartaric acid, and tannins. Chilling the wine before filtration enhances the process. By effectively filtering out these components, the wine becomes visually clear, more stable, and enjoyable to drink.