ANNEX IIMETHODS OF ANALYSIS RELATING TO THE COMPOSITION OF EDIBLE CASEINS AND CASEINATES
METHOD 6
DETERMINATION OF pH
6.PROCEDURE
6.1.Preparation of the test sample
As described in Section 1.2 of the General Provisions.
6.2.Determination
6.2.1.Calibration of pH meter
Adjust the temperature of the buffer solutions (4.1) to 20 oC and calibrate the pH meter in accordance with the manufacturer's instructions.
NOTES
1.
The calibration should be carried out while the flasks are standing for 20 mintues (see 6.2.2).
2.
If a series of samples is being tested, check the calibration of the pH meter with one or more of the standard buffer solutions at least every 30 minutes.
6.2.2.Preparation of the test solution
Transfer to the beaker (5.7) 95 ml of water, add 5,0 grams of the test sample (6.1), and mix using the mixer (5.6) for 30 seconds.
Allow to stand for 20 minutes at about 20 oC, covered with a watch glass.
6.2.3.Measurement of pH
6.2.3.1.
Pour about 20 ml of the solution into the beaker (5.5) and immediately determine the pH of this liquid, using the pH meter (5.2) after having rinsed the glass electrode carefully with water.
6.2.3.2.
Measure the pH.