As described in the next section, both titratable acidity (TA) and pH are measures of acidity. However, for most process control purposes, pH is a more useful measurement. Many cheese makers, however, still use TA to monitor initial acid development (that is to check for culture activity) during the first hour after adding the culture. For this purpose, TA is a more reliable indicator because relative to pH measurement, it is more sensitive to small changes in milk acidity.