pH in fermentation: what does the number say?
Sour taste, a meter reading and acid content are related. They are not three names for the same thing.
A number describes a sample
pH expresses acidity on a logarithmic scale: a lower value indicates greater hydrogen ion activity. A change of one unit corresponds to a tenfold change in that activity. It does not mean a tenfold increase in sour taste.
pH and titratable acidity
Titratable acidity describes the amount of base needed to reach a defined titration endpoint. It is a different measurement from pH. You therefore cannot simply convert a meter reading into grams of acid in a jar.
Record conditions, not just digits
Note the date, sample ID, temperature and method. State whether you measured brine or a prepared product sample. Follow your instrument’s instructions for calibration and sample preparation. Without this context, a result is difficult to compare with the next one.
Keep conclusions proportionate
A falling pH may be consistent with acidification. It cannot identify microbial species, toxins or shelf life. Use a tested recipe and appropriate process conditions; do not treat one number as permission to taste an uncertain batch.