Fish or Fowl… what is in my wine?

Why might the wine I am drinking contain traces of fish (Isinglass) or eggs as indicated on some bottles of wine?

That’s a good question. These traces can be found in some wines because of the clarification processes used in the final stages of wine making.

One of the natural results of the winemaking process is that impurities such as proteins, yeast or other organic particles can remain suspended in juice. These impurities, if left in the finished wine, could potentially produce a product that is cloudy in appearance or that is flavour-tainted and inconsistent. One of the methods used to remove these particles is fining using a variety of different agents.

The following are some common fining agents used in the clarification process:

• Isinglass is a substance derived from the swim bladders of fish. It is a form of collagen used mainly for the clarification and fining of white wine and beer. It provides excellent clarity and intensifies the colour in white wine.
• Casein is a protein derived from cows’ milk. It provides good clarification and treats and prevents oxidation in white wines and sherries.
• Gelatin, derived from animal collagen, is used effectively to clarify both red and white wines. It also aids in reducing bitterness from phenolic compounds. Care must be taken, however, in that aggressive use of gelatin can result in colour degradation in red wines.
• Albumen, derived from egg whites, is a very good fining agent for red wines. In addition to clarifying the wine, it is also effective in reducing astringency.
• Bentonite clay is also a common agent used in the fining process. It is primarily used in white wines since it can have a negative effect on the colour in red wines. It is sometimes used in combination with protein fining agents to assist in settling.

In terms of how and when they are used, the chosen fining agents are selected and added to the top of the vat in the final stages of wine production. It may also be used in the barrel. As the fining agent sinks down through the wine, any particles and impurities left in the wine adhere to them. The resulting sediment then collects at the bottom of the vat and is removed using either filtration or racking.

Because of the nature of this process, whereby the impurities and fining agents combine, only minute traces, if any at all, of the fining agent remains in the finished product, which is subsequently bottled and sold. When the fining agent used originates in animals it is a legal requirement in some countries to declare what products have potentially been used during the production of each wine. Irrespective of how little remains in the wine. Even where it is not a legal requirement, some producers are voluntarily putting that declaration on the bottle for the information of consumers.

Vita Vinum Est