These materials are used to solve specific wine problems. For example, bentonite is always added to white and blush wines. The bentonite removes excess protein and prevents protein from forming a haze after the wine is bottled. Small amounts of sulfur dioxide are added when the grapes are crushed, and small additions of sulfur dioxide continue until the wine is bottled.
Sulfur dioxide helps control the growth of microorganisms, and it reduces the effects of oxidation.
Wines fermented from apples and stone fruits often contain excessive amounts of pectin. The pectin makes the wine difficult to clarify, so winemakers add enzymes to break down the pectin. The most common wine additives are sulfur dioxide, fining agents, stabilizing materials and wine preservatives. Most materials used in winemaking are also used throughout the food and beverage industries. These materials are widely used and available to the winemaker as normal commercial products.