AOAC Official Method 941.07 Alkalinity of Ash of Dry Skim Milk

Titrimetric Method
First Action 1941
Final Action

Ash 2 g dry skim milk 1 h at £550°C. Add few mL H2O to ash,break up with flat-end stirring rod, evaporate to dryness over steam bath, again ash 1 h, and weigh. Again add few mL H2O to ash, break up, and transfer to beaker with 50–75 mL H2O. Add 50 mL 0.1M HCl, heat to boiling, and boil gently 5 min. Cool, add 30 mL 40% CaCl2 solution (w/v) (neutralized with 0.1M HCl and filtered) and ca 10 drops phenolphthalein, and titrate excess acid with 0.1M NaOH.
Acid used (mL) ´50 = alkalinity of ash
References: JAOAC 24, 744(1941); 25, 253, 610(1942); 28, 205(1945).