Fining Finished White Wine
A white wine is usually fined in order to soften a harsh or astringent character, to improve clarity, and/or to create heat stability. Fining agents should be used at the lowest possible dosage needed to achieve the desired effect. Over dosage can often create a loss of mouthfeel, aroma and/or flavor. Due to the complexity of the chemical structures in wine, different fining agents will be more or less effective at achieving a desired result. We strongly recommend conducting a bench trial first to determine which product gives the results you are looking for. Then, once this has been decided, do a second trial to determine the ideal dosage rate that will give the desired results for the least amount of product used.
Subtractive fining treatments
Subtractive fining agents work by physically removing offending elements from the wine. (Addition by subtraction.)
Bentonite is a special type of clay that is used to remove proteins from wine. Bentonites for winemaking are either sodium-based or calcium-based. Sodium-based bentonite is added to a small amount of water and allowed to swell for 24 hours until it become a thick slurry that is then added to the wine. Calcium-based bentonites are made to be added directly to the wine. This is a very effective treatment, but there is a downside: depending on the type of Bentonite used the lees can be very fluffy and result in a loss of wine volume when the treated wine gets racked off of the deposit. Sodium based Bentonite is very fluffy and for that reason is usually accompanied by a light gelatin or silica-gel dosage to help compact the final treatment lees, reducing volume loss. Calcium based Bentonites are not quite as effective as Sodium based ones, so you wind up using a bit more to get the job done. However, they have the benefit of being very compact in the final lees so there is little loss of wine post treatment. Calcium based Bentonites also benefit from a light gelatin or silica-gel dosage not for compacting the lees during settling, but for clearing out any fine particles that may be slow to settle once the main deposit has dropped. Once added to the wine, the reaction product is allowed to settle out and the wine is then racked away from the deposit.
Bentonite reacts most effectively at 60-75 F, so if possible allow the wine to warm up to 60-65 F for the fining. Once the reaction takes place go ahead and cool the wine back to the desired cellar temp.
Note: you can do both a cold and hot stabilization by warming the wine to 60-65 F, doing the bentonite fining, and then cooling the wine to ≤40 F. The cold and the potassium bitartrate crystals that form will help compact the bentonite/protein lees and will help minimize loss of wine volume!
(for more information on bentonite and heat stability see below, 7.3 B)
Gelatins/Isinglass are specially purified proteins that can be used to reduce tannins and help clarify a wine. Depending on the specific type, gelatins are mixed with either hot or cold water to form a solution, which gets mixed into the wine. After waiting the prescribed time, the wine gets racked off of the sediment.
Note: there are many types of gelatin available to winemakers; some are generalized and have a “blanket” effect of working on the entire range of tannins in the wine, while others are more specialized and target a specific type of tannin/polyphenol. Make sure the one you use is designed to give the results you are looking for. In white wines, we recommend using "Ichtyocolle” (FIN74) for clarification and for helping compact bentonite treatment lees.
Casein (Potassium Caseinate), “Casei Plus” (FIN70) is a milk-derived protein that is used to reduce astringency and soften a white wine’s tannin structure (i.e.: removing the aggressive oak character from an over-oaked wine). In addition, casein can also be used for removing browning from oxidative reactions. Once added to the wine, Potassium Caseinate is quick to settle and the treated wine can usually be racked in 4 days.
Note: If used to correct browning from oxidation, casein is often more effective when used in conjunction with PVPP.
PVPP (Polyvinylpolypyrolidone) is a synthetic polymer that is used for removing bitter and astringent oxidizable polyphenols (the compounds responsible for wine turning brown when it oxidizes!). PVPP can be used preventatively (as it is when it is used as part of "Polylact" to treat the pressed juice pre-fermentation) or as a cure for removing bitterness and brown color from oxidized wine.
Note: If used to correct browning from oxidation, PVPP is often more effective when used in conjunction with casein.
“Polylact” (FIN73) is a specialized blend of casein and PVPP in a pre-mixed, easy to use solution. Use it anywhere you would use either PVPP or casein, such as removing bitterness and as a curative or preventative treatment for oxidized browning in whites, rosés, and fruit wines. Can be used in both musts and finished wines (see product descriptions for directions/dosages).
Additive treatments (A.K.A.: “coating”)
The following treatments are considered to be “additive” because instead of removing the offending element, they work by coating or adding to the molecular structures that are responsible for creating the perception of harshness in the wine. While this may seem counterintuitive, “additive” treatments are often able to modify the aggressive/harsh character(s) you were trying to eliminate so that the need for further fining can be reduced or even unnecessary. Since the “coating” of tannins is an additive process, there is no danger of stripping anything out of the wine during the treatment. However, the one caveat to additive treatments is that if overdone, they can overpower subtle elements in the wine. Once again, bench trials and a conservative approach to your additions will help to avoid any problems.
Oenological tannins are used during the ageing/storage period to help develop mid-palate structure and positive mouthfeel characteristics in the wine. These tannins can be used to help round out a thin or aggressive wine. In addition, oenological tannins also add a layer of protection against oxidation.
Note: some oenological tannins are designed only for use during fermentation and others are specifically made for the ageing/storage period. So, make sure you choose the right one for the task at hand.
Galalcool SP (TAN150): Can be used during fermentation to minimize reductive odors and enhance mouthfeel. It is usually used for white wines, but can be used for fruitwines and mead, as well.
Toasted Oak (chips/cubes) is an economic source of wood (also called ellagic) tannin that will help stabilize color and add body during fermentation. Toasted oak will also give some finished flavor complexity to the wine. Can be used with enological tannins as a spice/flavor component. (For a complete explanation on the use of oak in winemaking see section 9.9)
-Dosage rate for chips/cubes is 1-4 lb per 1000 lb of fruit (or 1.6 to 6.4 ounces per 100 lb of fruit), with the low end being used for stabilizing color and structure, and the high end being used to minimize vegetal characteristics.
Opti-White/Sur-Lie are specially designed, yeast-derived protein fractions that can be used to add mouthfeel, body, and perceived sweetness to a wine. Normally used in the fermentation, these products can also be used to round harsh/aggressive tannins and bright acidity in finished wine during ageing/storage. Like tannins, Opti-White/Sur-Lie (Bio lees) add a layer of protection against oxidation to help protect the wine during the ageing/storage period.
Note: When Opti-White/Sur-Lie additions are overdone, they can create a candied sweetness that comes across as artificial. Watch out for this during your bench trial.
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