Acidity Management in Musts and Wines by Schneider Volker & Troxell Sarah

Author:Schneider, Volker & Troxell, Sarah [Schneider, Volker]
Language: eng
Format: azw3
Publisher: Board and Bench Publishing
Published: 2018-09-30T16:00:00+00:00

As for acidification trials outlined in sensory exercise 4, every winemaker would be well advised to keep a KHCO3 or K2CO3 test solution at hand. Its frequent use will help understand why minor deacidifications are a powerful tool of sensory optimization, much more powerful than a large range of commercial additives usually recommended for that purpose.

5.3. Peculiarities of red wine deacidification with potassium carbonates

For red wines, malolactic fermentation (MLF) is considered indispensable and commonly used on all red wines from virtually all climates and varieties. The reason is that is does not only decrease acidity, but also improves complexity and mouthfeel of the wines (Chapter 8). Additionally, the decay of malic acid it causes provides better microbial stability. This is an important issue in red wines since in contrast to white wines, they tend to show higher pH figures and are usually stored and bottled with lower levels of free SO2. As a result, they also have lower levels of molecular SO2 protecting the wine against detrimental microbial activities (Figure 3). If they still contain malic acid at the moment of bottling and if bottling is not carried out under sterile conditions, the risk of postbottling MLF will considerably increase.

Usually, MLF is deemed sufficient for achieving acidity balance in red wines, but this does not necessarily apply when they are grown under cool-climate conditions or obtained from unusual varieties. In those wines, high residual TA levels and low pH figures increase the astringency of tannins (Guinard et al. 1986, Fontoin et al. 2008) and lessen the perception of volume and weight. This is the reason why an additional chemical deacidification can become necessary after MLF is completed—a procedure hardly understandable for hot-climate wine growers.

Figure 9 shows the sensory changes on the palate caused by a post-MLF deacidification of a Merlot red wine from 5.7 to 4.7 g/L TA using KHCO3. They affect much more than only sourness. Since sourness and volume are sensory antipodes, one affecting another, deacidification strongly enhances what is perceived as weight and volume on the palate.

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