One of a wine's primary flavor elements is acidity. Wines that are high in acid will taste sharp or sour, while wines low in acid will taste lifeless or flabby. Without a doubt, having the proper amount of acid is crucial to the flavor of your wine.
In many fruit wine recipes, the amount of acid or acid blend that should be added to the wine must is listed right along with the other wine making ingredients. By adding the acid blend called for, you are bringing the acid level of the wine up to a normal flavor range.
The reason you are able to get your wine into a proper range using these wine recipes with no issue is primarily because they are made up of a significant amount of water. This makes the amount of acid blend needed very predictable since a only a fraction of the total acidity is coming from the fruit itself.
But there are situations where acidity is not so predicable and acid readings need to be taken to know how much acid blend, if any, needs to be added. Such is usually the case when making wine from actual wine grapes, where the wine is made up of 100% grape juice with no water. If the acidity of the grapes are unusually high or low in a particular year, the flavor of the resulting wine will be negatively affected. In this scenario, taking an acid reading with an acid testing kit can be just as critical as taking a sugar level reading with a wine hydrometer.
Acid readings are normally taken right before fermentation, or right after the grapes have been ran through the grape crusher. Adjustments may be made at this time based on the reading given.
Taking readings with an acid testing kit is very straight-forward. Essentially, what you are doing is preforming a titration. A drop or two of activator is added to a measured sample of the wine. Then measured amounts of a reagent are added to the wine until you detect a permanent color change in the wine sample. By knowing how much reagent it took to change the wine's color, you can accurately calculate the wine's acid level. You can read more about this in the blog post Use an Acid Test Kit.
If the acidity is too low you add acid blend; if the acidity is too high you can dilute with water. We also have wine making products such as acid reducing crystals that are designed to reduce the acidity of the wine. The acid reducing crystals come with directions that will tell you how much to add to reduce the acidity by a specific amount.
Ed Kraus is a 3rd generation home brewer/winemaker and has been an owner of E. C. Kraus since 1999. He has been helping individuals make better wine and beer for over 25 years.