The ascending method of limits was used to determine the BET
of the hydrogen ions in water. In this experiment, the acid used
was hydrochloric acid. 16 experienced tasters were employed for
this purpose; their individual BETs ranged from 0.102 to
3.236 mM, namely the pH range of 2.49 to 3.99 (Table 1). The
group’s BET was found to be 0.575 mM, and the corresponding
pH value was 3.24. The results show that for most people, a sour
taste was perceived when the concentration of free hydrogen ions
was over 0.575 mM, or the pH value was below 3.24.