Fining is important part of the winemaking process where a fining agent is added to the wine to create an absorbent, enzymatic or ionic bond with the suspended particles, making them a larger molecule that can precipitate out of the wine easier and quicker. Fining agents is used to reduce astringency and remove tannins, microscopic particles and clarifying the grape juice or wines, they also take out some aroma and flavor. The fining agents can be organic and inorganic or mixtures of both. Some work electrochemically, with the agent having a positive charge attracting negatively charged particles and bind with them.

Lab tests should be performed in order to determine the proper amount of the fining agent to be added to the wine.


Copper Addition

Copper sulfate (CuSO4) is a fining agent used to remove unpleasant hydrogen sulfide (H2S) and other “sulfide-like” off aromas in wine. The hydrogen sulfide is generally described as rotten-egg-like off aromas.H2S is volatile natural product of the fermentation and it can be present into the wine as mono-mercaptans (sulfides), which can be treated with copper or poly-mercaptans (disulfides) which will not react with copper, so deal with the problem as soon as it is detected. Copper when added to wine containing “sulfide-like” off aromas immediately reacts with H2S and form copper sulphide, immediately. If the copper ions is not removed from the wine after the treatment with the proper fining agent or filtered out, a haze may appear. Most of the time copper is added to the wine in the form of Copper Sulfate s(CuSO4 • 5 H2O), also known as Copper Sulfate solution.

To avoid over adjustment, copper lab trial should be performed.

Oak Addition

The oak alternatives become important part of the modern winemaking, due to their ease of use and the increasing cost of new oak barrels. There are many different types of oak-alternative products such as oak chips, oak powder and oak staves. They can be added at various stages of the winemaking process, during fermentation or the aging of the wine. The benefits is that, they can give quickly specific oak flavors and aromas, more complexity, structure and some sweetness, which will be make the wine more balanced. Different types of oak alternatives can give wine different flavor component like a toasted nuts, vanilla, caramel, coffee and some toasting spiciness. Winemakers who use oak alternatives often use micro-oxygenation to help simulate the oxygen exchange of traditional oak barrels. 

Summary of Fining Agent Use

Weight and Volume equivalents