Tasting and Adjusting Whites During Ageing
Throughout the entire maturation period we need to occasionally check in on the wine’s progress by testing and tasting it. We like an interval of roughly every 4-6 weeks. What we are looking for is the following:
Is everything all right? Is the wine still fresh and fruity? Or, are there any funky, undesirable flavors or aromas developing since the last time you checked the wine? If there are any problems, they will need to be dealt with ASAP, because the longer problems are left uncorrected the harder they are to remedy.
Note: In the midst of analyzing/troubleshooting, don’t forget to check both the SO2 levels and the pH/TA to see if these have shifted from the last time the wine was tested. This will help you – or us - to figure out what is going on with the wine if there is a problem.
Assuming there are no signs of spoilage, then how is the wine developing? You’ll want to look at a few different aspects of the wine to check to see if there’s anything that you want to alter or adjust.
A. pH/TA: How does the wine taste? Is it too acidic or too flat? Check what you taste against the pH and TA results. If you need to raise the pH because the wine is too acidic you can use one of the two products:
Potassium Carbonate used at a rate of 3.8 grams per gallon will raise the pH by approximately 0.10 units (a bench trial is highly recommended). When you use Potassium Carbonate you will need to chill the wine to below 40°F for a minimum of two weeks. Potassium Carbonate requires cold temperatures in for the treatment to be effective. Chilling the wine also has the beneficial effect of making the wine cold-stable at the same time. However, if the wine cannot be chilled then the Potassium Carbonate will never drop out and remain in solution, thus ruining the wine. So do not use Potassium Carbonate unless you can chill the wine to at least 40F for a two- week period.
Calcium Carbonate used at a rate of 2.5 grams per gallon will raise pH by approximately 0.10 units (a bench trial is highly recommended). Calcium Carbonate does not require cold to work; in fact cold temperatures delay settling (so make sure it has dropped out of a wine before you cold-stabilize it). However, Calcium Carbonate can takes months to precipitate out of a wine and it can effect flavor more than Potassium Carbonate. So, if possible it is recommended to use Potassium Carbonate to reduce acidity in your wines.
When done with either Potassium or Calcium Carbonate, rack it off of the deposit, double check the pH, TA% and SO2 level and return to the normal ageing/storage schedule.
If the wine is too flat and could use a little brightening-up, it can be remedied by a Tartaric acid addition. (3.8 grams per gallon raises the TA by approximately 1.0 g/L, a bench trial is highly recommended to determine the best dosage rate).
Refer to our guide for a complete explanation of Adjusting Acidity.
Mouthfeel/Structure: How does the wine seem when you roll it around in your mouth? Is it thin or full? Depending on the varietal and the style of the wine being made thin may be perfect - a delicate Riesling, for example. However, if you are looking for a wine that is a little more full then you may want to look at using a small amount of yeast-derived additives such as Opti-White, Noblesse, Sur-Lie, or enological tannins to help round things out.
Note: If you are ageing on the lees, just keep stirring to gain fullness.
Tannin/Oak Extracts/Level of Barrel Impact: If you are using oak, each time you taste the wine you need to pay attention to how well the tannins, flavors and aromas coming from the toasted oak are interacting with the wine. It is always easy to add a little more oak or tannin to the wine if the levels are not highenough, but be careful to not over do it. The only way to tone it down is by blending it out with another wine that has less oak/tannins. For more information on using oak in winemaking, see section 9.9
Note: Due to the complexity of wine, the only way to precisely gauge how much of each product is needed to achieve your desired results for any of these addition/adjustments is to do a bench trial. This cannot be stressed enough: the place to find out that the 0.2 pH rise in your wine that was supposed to come from a 2 g/L addition of Potassium Carbonate has now resulted in a 0.4 pH shift due to an unforeseen buffering reaction is in the test bottle and not your entire wine volume...
For complete information on bench trials, see our Guide to Bench Trials.
If you are not working with the lees: Depending on how much sediment has settled out during ageing, you can choose to rack the wine off the deposit during its maturation to help promote clarity. If you are careful during racking and don’t stir-up a lot of sediment when you transfer the wine you will probably only need to do this once or twice.
If you are working with the lees: You will only be racking it once the desired lees impact has been reached.
We recommend, if you are so equipped, purging the transfer lines and the receiving vessel with inert gas before making any white wine transfer. This will keep the wine from excessive contact with oxygen and thus retain more of the wine’s aromatic character. The following basic check list should be gone over before any racking:
Test your free SO2 level. Make sure you have at least a portion of your free level in the wine before you make your transfer. This will serve as an internal protection during the transfer in case of oxygen exposure or potential spoilage organisms. Once the transfer is complete make sure to bring the free SO2 up to the required level before closing the wine up for the next 4-6 weeks.
If you made any acid adjustments, it would be a good idea to test the TA and see if it needs more. However, don’t just go by the numbers alone, taste the wine and see what you think it needs, if anything at all.
Check the amount of oak/tannin integration. Oak compounds are continuously being released from the wood into the wine throughout the ageing/storage process. It is important to monitor their integration into the wine during this period so that the oak character does not become too strong, overpowering the wine. In general, if you use the recommended level of oak in your wines (1.5 - 2 oz. of oak cubes per 5 gallon carboy, or actual barrels themselves), and taste/monitor the progress every 4-6 weeks, you will be able to avoid accidentally over-oaking your wine.
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