Determining the acidity of wine.
As long as sugar is the basis of the subsequent alcohol content, the acid shapes the aroma and taste of the wine. Both factors must be in a favorable relationship to each other. Such a harmonious relationship only occurs in good years and only in the case of grapes and apples. In normal years, you have to help nature a little. There is nothing blameworthy about it; who can affect unfavorable climatic conditions, prevailing with us, in Central Europe?
Only a specialized laboratory can perform a precise analysis of the acid content of the juice or wine.
However, this kind of thorough research is not necessary for homemade wine. We determine the total acidity of the wine or juice using an acid meter.
The acid meter consists of a cylindrical glass vessel with a capacity 20 ml graduated in degrees- In addition, they are needed: a bottle of blue lye (standard solution) and a pack of litmus papers.
The measurement is performed as follows: the blue liquid liquor is added to the juice or wine for so long, until the wine or juice neutralizes it. Means, that the amount of acid must be the same as the amount of lye. The neutralization can be known by changing the color from yellow (the color of the juice or wine) through green to blue.
To mark the exact value, first, a cylindrical vessel is filled with juice up to the height of the scale "0", and then the blue lye is added dropwise. You still need to shake the dish, closing the hole with your thumb, so that both fluids mix well. When the yellow color darkens, to finally turn into spring green, only a minimal amount of lye can be added, until more or less, when light green turns into dark. Under no circumstances should this happen, so that the juice turns blue, this would be tantamount to exceeding the most favorable measuring point.
Now you can read the scale on the scale, how many cubic centimeters of lye were added to the juice. The quantity read (e.g.. 7) is the acid content of the juice, determined in grams per liter (g/l).
In the following, we will deal with the weight of the must and the total acidity; both of these values are an essential basis for the subsequent refinement of wine.
The acidity of a good juice should be 6-8 g/l.