The electrodes of pH can be classified according to different criteria:
- According to the material from which they are made i.e. metal or glass
- According to their shape and function, they are classified as "Normal" or for "Immersion" or "Penetration". The Normal electrode is used to measure the homogeneity of meat, while those that have a sharp point can measure pH of pieces of meat or the entire carcass (by taking several samples).
The electrodes can have an electrolytic solution within potassium chloride 3M or else a polymeric conductor (Xerolyt or similar). The electrodes can deteriorate to such an extent that a dramatic change in their characteristics can be observed. The possible effects and causes for this deterioration are:
- An increase in the period of response (a dirty diaphragm or dehydrated membrane).
- Instability in the readings (dirty diaphragm and membrane or damaged reference system).
- Displaced asymmetry potential (dirty diaphragm or deteriorated reference system).
- Reduction in gradient (dirty diaphragm or dehydrated membrane).
All these problems can always be solved with specific cleaning products, repositioning the electrolyte or by recovering the reference system. The electrodes must be protected by the membrane being completely submerged in the solution of the potassium chloride (3M), and if necessary the interior maintenance solution must be topped up.