Why are Clearing Agents used in Wines?
Good quality wine should be clear. If you are new at fermenting wine, then you must have experienced times when your wine came out cloudy. A cloudy wine means that there are small particles that have suspended within the liquid that formed during the fermentation process. This is normal and wines eventually clear up through racking, but if it doesn't, then you can use fining agents for your wine to aid in clarification.
To get all the suspended particles out, fining agents are used to bond with the charged solids thus forcing them to settle in the bottom. In the past, fining agents would include fish bladders, clay and bull's blood. It does sound nasty, but you don't really have to use them today as there are chemicals available to help clear your wine. There are several types of fining agents that winemakers use when making wine today.
One of the most common fining agents is bentonite. Bentonite is negatively charged and is made from volcanic clay. It works by attracting positively charged particles from the wine to bind them together. You know that it is working effectively when it swells into a huge ball and once it does, you remove it from your wine.
Chitosan, on the other hand, is a positively charged fining agent. It is made from the exoskeleton of crabs and shrimps and is often used with other negatively charged fining agents for the effective removal of solids.
If you don't have access to these fining agents, then you can use egg whites and gelatin. Both are positively-charged. Egg whites are often used to clear red wines during the ageing process. Gelatin, on the other hand, can be used in both red and white wines but too much can cause the wine to have a hazy appearance.