[Information based on DipWSET D1 material]
There are certain adjustments winemakers can make to a must wine, pre or post-fermentation. The goal is always to make a more balanced wine, so any and all adjustments should be monitored and measured carefully. Also note that, in many regions, the amount of adjustment(s) that can be made are strictly regulated.
I find I get the pre- and post-fermentation adjustments confused, so thought I’d create a little study guide here. Enjoy.
Enrichment refers to a range of practices including adding dry sugar (chapitalization), grape must, grape concentrate, or rectified concentrated grape must (RCGM) to increase the sugar content and, thus, the final alcohol level of the wine. This can be done either before or during fermentation, but is thought to be better achieved while fermentation is going on because yeasts are already active and ready to deal with that extra sugar.
Sugar level of must can also become concentrated by removing water: reverse osmosis, vacuum evaporation, or cryoextraction (freezing must or final wine, and removing ice from it).
Enrichment is a common practice for those in cooler climates, where natural sugar levels may be too low.
2. REDUCING ALCOHOL
This is basically the opposite of number 1 and refers to adding water to the grape must to reduce total sugars and potential alcohol. However, it’s noted that adding water will also dilute flavors and aromas, as well as acid level.
If removing alcohol post-fermentation one can do so either by
- Reverse osmosis: a form of cross-flow filtration that removes a flavorless permeate of alcohol and water, which is then distilled to remove the alcohol. The permeate is then blended back in to recreate a reduced alcohol wine.
- Spinning cone: this device extracts volatile aroma compounds and then removes alcohol. The flavor components are then blended back in.
Adding in acid is a lot more common than you think. In fact, I recently learned that nearly every wine out of the Willamette Valley sees some amount of acidification. In warm regions that have limited cooling influences, malic acid drops significantly (as it is used for respiration during ripening period) and consequently dropping the fruit’s total acid level. Resulting wines could become flat and flabby without the addition of acid. Acidification can also be used to adjust a wine’s pH, which, as we learned in a previous post, has an affect on the wine’s microbial stability and ability to utilize smaller amounts of SO2 additions more efficiently. (A low pH also assists with providing red wine with brighter coloring and also affects age-ability).
Acidification can take place before, after, or during fermentation, but it’s preferable before fermentation in order to take advantage of the resulting lower pH. (It’s also thought that it will better integrate with the wine if it’s part of the fermentation process.)
NOTE: Total acidity and pH are affected during the natural winemaking process—even without adjustments. So, one has to be quite careful in deciding how much acid to add.
Types of acids used:
- Citric (not permitted in the E.U.)
- Malic (not common, as it can turn into lactic acid later on)
- Lactic (more typical in adjustments made post-MLF; lactic acid is less intense than the above)
Deacidification is carried out by adding calcium carbonate (aka chalk) or potassium carbonate, each of which lowers total acidity by forming and precipitating tartrate crystals. [There’s a secret high-tech option, called ion exchange, but it is very expensive and, in some places, illegal. The process does not remove tartrates, but actually replaces the potassium and calcium ions with hydrogen or sodium ions.]
Deacidification is common in cool climates and/or in vintages when grapes will need to be picked before fully ripe (due to threats/hazards during harvest season).
NOTE: Deacidification must take into account the natural lowering of acidity during the winemaking process, specifically if/where MLF is allowed to be carried out.
5. COLOR ADJUSTMENT
In some cases, winemakers may want to reduce unwanted color tints. You can read about some of the clarification options to adjust color here, but typical agents for red wine include egg whites, gelatin, vegetable proteins, and PVPP; white wine color-clarifying agents include gelatin, casein, isinglass, PVPP, vegetable proteins, and charcoal.
In large volume productions, sometimes there’s a need to intensify the color of red wine, and this will be done by adding a small amount of a grape-derived coloring agent (MegaPurple). NOTE: This is not allowed within some regions.
6. MUST CONCENTRATION
I’m adding this in here, though it’s not included in this section of my book, but in my eyes, this also counts as a kind of must adjustment.
This options is very specific to red winemaking (and potentially rosé as well). Post-crush, winemakers may want to concentrate the must before fermentation starts. This lowers the total volume, but the new skin to juice ratio is much smaller, so the resulting red wine can become, potentially, more extractive. The wine that is removed is light in color, flavor, and tannin. The juice can then be used to make a rosé wine. The juice that is removed is often said to be “bled off,” so rosé made in this way is referred to by the French term saignée.
How’d I do? Did that all make sense? Anything I forgot or you want to add?
Thanks again for studying with me!
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