Wine Fining Practices
The effectiveness of a given fining agent depends on the agent itself, on fining trials, on method of addition, on order of addition, and on monitoring together with characteristics of the wine such as pH, metal content, temperature, presence of carbon dioxide, and prior wine treatments.
Regardless of the circumstances, it is advisable to carry out fining trials before fining a particular wine to assess the behavior of various products, possibly at several different doses. In evaluating fining agents, the winemaker must observe, note and record how each fining agent alters clarity, lees production, lees compaction, colloidal stability, color, body (front, middle, and finish), astringency, bitterness, the nose characteristics in general, the fruit, the finish, the aging potential, and overall wine palatability.
Methods in Adding Fining Agents
Successful fining depends on the rapid mixing of the fining agent with the wine. The difficulty of this operation varies according to the volume to be treated. The fining agent must be dispersed throughout the entire mass of wine evenly but also immediately, otherwise it is likely to finish coagulating before it is completely mixed with the wine, thus reducing its effectiveness. Systems to aid complete dispersal are essential.
Order of Addition with Fining Agents
There many different opinions about the correct order of addition of fining agents when using more than one fining agent. A guideline can probably be found by answering the following question: what is the goal? For example, with white wine if the goal of fining is to improve protein stability, adding bentonite first improves its stabilizing effect.
When fining white, rose or other low tannin wines, some protein-based fining agents, particularly gelatin and isinglass, which have a positive electric charge, require the addition of negatively charged colloids in order to ensure complete flocculation and, eventually, precipitation. Such negatively charged flocculation aids include: tannin, silica sol and bentonite.
Routine, periodic monitoring of the fining process shall be conducted. In general, this will entail analysis of a sample of fined wine using a sufficiently sensitive method of analysis for the fining agent in question.
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