Preparation of test sample procedure es puter AOAC 969.20, 2007
7 mL H
2
SO
4
were added, also boiling chips which pass No. 10 sieve. Test portion was digested 1 h after all H
2
O is distilled and acid comes to true boil. Minimum volume of H
2
O was added to dissolve solids, cooled, and thin film of petroleum jelly placed on rim of flask. Digested and boiling chips
transferred to distillation apparatus and flask rinsed 6 times with 2 mL portions H
2
O. Under condenser with tip extending below surface of solution was placed 125 mL Erlenmeyer contained 5 mL saturated H
3
BO
3
solution and 4 drops indicator Added 10 mL NaOH-Na
2
S
2
O
3
solution to still, collected ca 15 mL distillate, and diluted to ca 50 mL. Titrated to end point. Made blank
determination and calculate. Nitrogen content calculated by the equation:
Nitrogen wet basis =
normality HCl × corrected acid volume mL × . g Nmol
weight of wet sample g
× Nitrogen dry basis =
normality HCl × corrected acid volume mL × . g Nmol
weight of dried sample g
× Protein = N × Protein factor
= N × 5.45 combination of coconut and rice protein factor