Malt intended for use in beer brewing or elsewhere in the food industry
The value of pH is defined as the negative decadal logarithm of the concentration of hydrogen, or more precisely, hydronium ions:
\(\text{ pH }=-\log{ c_{ H_{ 3 }O^{ + } } }\)
The pH scale, ranging from 0–14, is based on the dissociation equilibrium.
The pH value of a liquid is commonly determined with a pH measurement device consisting of the measurement electrode (glass) and the reference electrode (e.g., silver/silver chloride electrode), which is connected to a signal amplifier and a display instrument. The device is calibrated using standard buffer solutions.
The pH reading displayed is determined through the difference in electrical potential between the reference solution in the electrode and the solution being measured.
Generally, a pH measurement system is used, in which the measurement and reference electrodes are combined to form a single unit.
Determination of the total oxygen content (dissolved and in the headspace) in filled containers
The bottled or canned beer is brought to 20 °C and mechanically shaken, thereby achieving equilibrium between the oxygen dissolved in the beer and the oxygen present in the headspace (Henry’s and Dalton’s laws). By directly measuring either the oxygen in the beer or in the headspace, the total oxygen can be calculated through referencing a table of values, which includes the headspace volume as a percentage of the fill volume.