AOAC Official Method 931.07 Glucose and Sucrose in Eggs Sugar Inversion Method
First Action 1931
Final Action
A. Preparation of Solution
(a) Liquid eggs.—Weigh, by difference, ca 25 g well-mixed test portion, 925.29(a) or (b) (see 34.1.01), into 250 mL volumetric flask containing 1 g CaCO3 and 50 mL 5% NaCl solution (w/v). Record test portion weight to nearest 0.0001 g. Add 130 mL alcohol with continuous mixing. Let stand few min for gas bubbles to rise to surface, cool to room temperature, dilute to volume withH2O, mix, and filter (18.5 cm folded paper). Transfer 150 mL filtrate to 250 mL beaker and evaporate to 20–30 mL to remove alcohol. Cool, and wash with H2O into 100 mL volumetric flask, holding volume to 80–90 mL. Add dry powdered phosphotungstic acid in small amounts in slight excess to precipitate any protein, mix, let stand few min for gas bubbles to rise to surface, dilute to volume with H2O, mix, and filter. To filtrate add, in very small portions, enough dry powdered KCl to precipitate any excess phosphotungstic acid, filter if necessary, and test filtrate for complete precipitaten.
