AOAC Official Method 933.05 Fat in Cheese
First Action 1933
Final Action
IDF–ISO–AOAC Method
Codex-Adopted–AOAC Method*
Weigh, to nearest mg, ca 1 g prepared test portion, 955.30 (see 33.7.02), into small tall-form beaker or directly into extraction flask; add 9mLH2O and, if desired, 1 mL NH4OH. Mix until smooth; then warm mixture at low heat until casein is well softened. If NH4OH was used, neutralize with HCl, using litmus as indicator. Add 10 mL HCl and few glass beads or other inert material, previously digested with HCl, to prevent bumping, cover with watch glass, and boil gently 5 min, or place beaker or extraction flask in boiling H2O bath 20 min. Cool solution; transfer to fat-extraction flask or tube; rinse beaker successively with 10 mL alcohol, 25 mL ether, and 25 mL petroleum ether (boiling range 30–60°C); transfer rinsings to flask; and mix thoroughly after adding each reagent. Proceed as in 989.05 (see 33.2.26), beginning “Centrifuge flask . . .” and 989.05 (see 33.2.26). Difference between duplicate determinations obtained simultaneously by same analyst should be £0.2 g fat/100 g product.
References: JAOAC 16, 584(1933); 31, 300(1948); 32, 303(1949); 52, 240(1969).
Revised: March 1996
