Fining and Other Adjustments


# **Fining & other wine adjustments** In this post, we are doing a deep dive into "fining" and other wine adjustments. That is, adjustments made to wine after the primary alcoholic fermentation, and in some cases, the secondary malolactic fermentation. This is a polarizing topic as many believe that making adjustments to wine constitutes manipulation and some even go as far as calling it cheating as **[this](** article by Clark Smith talks about. Smith thinks the time has come to challenge these views and that : "To dishonor our craft is both insulting and naïve. Winemaking is, after all, just a form of food preparation – the ultimate slow food. Chefs are supposed to manipulate things. It's what we do." It is of course perfectly possible to enjoy wine without knowing anything about how wine is made - just as it is possible to enjoy food without knowing anything about cooking. But we know that many of our members in the Modern Wine Club, find it interesting to expand their knowledge of winemaking at a more technical level so sit back with a glass of wine and we'll peak inside the "black box" of winemaking to look at how wine is crafted by skillful winemakers applying the toolbox of chemistry. **What is Fining?** "Fining" is the deliberate addition of an adsorptive compound followed by the settling or precipitation of partially soluble components from the wine. In short, fining means putting something into the wine in order to take something out of the wine. There are three key reasons for using fining: - Clarity: To improve the clarity of the wine. - Stability: To remove particles that can cause haze or sediment in the bottles - especially as the bottles are chilled or heated. - Improve Sensory Properties: To adjust the flavors and aromas of wine so that it becomes a more pleasant drinking experience. This definition of fining means that pure additions, e.g. of acid to increase tartness or of grape juice concentrate to increase sweetness, are technically not fining as nothing is removed from the wine. Hence, such interventions fall under the banner of other wine adjustments rather than fining.  **Fining Agents** A wide variety of fining agents exist of which many, but not all, are animal proteins. The table below summarizes key use cases for fining and the effectiveness of commonly used fining agents. The agents listed towards the top of the table have the most potent effect. As you can see from the table above, a key feature of fining agents is that they often have a simultaneous impact on several attributes of the wine (i.e. the same agent appears in multiple columns). Thus, there is a risk of adverse side effects beyond the primary purpose of applying the fining agent. Some agents tend to have a generally strong impact (e.g. gelatin) while others are milder (e.g. isinglass). In practice, winemakers often have "pet" fining agents that they are more familiar with than others based on years of usage. As such "habit" sometimes trumps the latest "best practice" in that many winemakers simply keep using what they are familiar with. Next, let's take a look at some of the most common fining agents. **Gelatin** Gelatin is protein sourced from cows, pigs or fish. It is highly effective at removing tannins from red wine making it a weapon of choice when the objective is to reduce astringency and bitterness from red wine. A typical use case for this is to make tannic red wine accessible when young as opposed to after extensive bottle maturation when initially finely dispersed and "dusty" tannin monomers polymerize, sometimes even to the point of precipitation causing tannin sediment in the bottles. Gelatin is also effective at stripping wine of its color and thus needs to be applied with caution as this is not always a desired characteritic for red wines while it may be used to remove brown and yellow color from oxidized white wines. Of all the commonly used agents it is the one with the greatest tendency to "overfine" the wines making small scale fining trials in the wine lab imperative before gelatin is applied at production scale. **Albumen** Albumen comes from egg whites and is a powerful fining agent to remove bitter phenolics and reduce astringency in wines. Like with gelatin, there is a risk of overfining given its potency. It has a long history of usage and many French winemakers apply 6-8 fresh egg whites per 225 liter barrel of red wine. In comparison, California winemakers are often giving their red wines a gentler treatment with only 1-2 fresh egg whites per barrel. This is an interesting case in that many believe that "New World" winemakers are more inclined to "manipulate" their wines. However, in the case of albumen, we know that it is often generously used in France to reduce astringency and bitterness in red wines. **Isinglass** Isinglass is a protein that many have not heard of outside of winemaking circles. It is extracted from sturgeon swim bladders so a protein derived from a fish. Isinglass is useful to remove bitterness and vegetal aromas from wine, and as a clarification agent also removing color from white wines. Compared to gelatin and albumen, Isinglass is considerably gentler in nature which reduces the risk of ruining the wine from overfining. It is a weapon of choice for fining delicate white and rosé wines. Casein Casein is a protein extracted from milk and has a bit of a general sponge effect on wine. Casein is capable of reducing bitterness and astringency, reducing oak aromas and removing color as a result of oxidation (e.g. yellow and brown color in white wines). It can also soak up mild smoke taint in wines made from grapes picked during and after wildfires. It is considerably gentler than activated carbon described below. **Carbon** Activated carbon is a very powerful fining agent and is usually not applied unless as a "last resort" kind of measure. It can be used to remove a lot of negative aroma compounds in wine, as well as color, but the drawback is that it also removes a lot of positive aromas. As such activated carbon is typically only applied after other, more gentle fining agents have failed to produce the desired outcome. It is also one of the most effective fining agents against wine damaged by smoke taint. The problematic aromas are often removed by activated carbon but the wine is typically also stripped of complexity and nuances. As such, wine treated with activated carbon may be better off for the bulk market than to be bottled under a premium winery's own brand. Activated carbon is thus usually not an ideal fining agent but rather a tool used as a last resort to recover cents on the dollar by selling declassified bulk wine rather than discarding the wine altogether.  **Bentonite** Bentonite is a montmorillonite clay that is very useful as a settling agent to separate wine from the lees (primarily dead yeast cells after completion of fermentation) and to remove proteins that can cause hazy/cloudy instability in wines. A downside of bentonite is that it can have a negative sensory impact. That is, similar to activated carbon, treatment with bentonite also risks stripping wine of desirable flavors and aromas. **Copper Sulfates** Copper sulfates are very effective against stinky aromas produced by mercaptans and volatile sulfur compounds. Such aromas are generally very unpleasant (e.g. rotten eggs, cabbage, skunk) and they often have an incredibly low sensory threshold for humans - sometimes as low as 1 part per billion or even less. When dealing with such unpleasant aromas in wine, copper sulfates are the weapon of choice for winemakers. A downside of the application of copper sulfates is that the agent increases oxidation of the wine being treated. **Acid Adjustments** In the event that a wine is too high in acidity (i.e. tart), common agents used to reduce acidity include calcium carbonate, potassium carbonate and potassium bicarbonate. Think of this as giving the wine a "Gaviscon" like treatment to rapidly bring down the level of acidity. In the opposite case, i.e. a wine lacking acidity and appearing flat, the common protocol is to add tartaric acid, an acid that is naturally occurring in grapes. **Sweetness Adjustments** As we discussed in the blog post about **[Flavor-aroma interactions in wine](**, sweetness plays a key role in masking astringency, bitterness and acidity in wine. In many wine regions, the direct addition of sugar (so called chaptalization) is not allowed but the addition of sweet grape juice concentrate is often allowed. This is similar to "sugaring the lemonade" in that adding sweetness can have a dramatic impact on making an otherwise astringent, bitter and tart wine a much more pleasant drinking experience.  **Polysaccharides** Polysaccharides are derived from either grapes or yeast and a lot has happened in terms of availability of enological polysaccharide additives. The addition of polysaccharides can substantially add mouthfeel / body to a wine. So a wine that feels a bit thin or weak can be substantially boosted with polysaccharides to create a more fulfilling drinking experience (i.e. a mouthfeel with more weight). We hope that you have enjoyed this peak into the "black box" of winemaking to show you what is really happening at wineries as winemakers craft the wines that eventually end up on your tables. The key message is that modern wines are "crafted" rather than magically appearing. Cheers!  Andreas Birnik