AOAC Official Method 940.37 Techniques for Eggs and Egg Products Microbiological Methods

AOAC Official Method 940.37 Techniques for Eggs and Egg Products
Microbiological Methods
First Action 1940
Final Action
A. Preparation of Test Portion
(a) Liquid eggs.—Thoroughly mix test sample with sterile spoon or sterile mechanical stirrer and prepare 1:10 dilution by aseptically weighing 11 g egg material into sterile wide-mouth glass-stoppered or screw-cap bottle; add 99 g sterile dilution H2O, 940.36A(a) (see 17.1.02), or sterile physiological salt solution, 940.36B(c) (see 17.1.02), and 1 tbsp sterile glass shot. Thoroughly agitate 1:10 dilution to ensure complete solution or distribution of egg material in diluent by shaking each container rapidly 25 times, each shake being up-and-down movement of ca 30 cm, time interval not exceeding
7 s. Let bubbles escape. Transfer representative portion from 1:10 dilution for higher serial dilutions as needed. Proceed as in B–F(a). Pour all plates and inoculate other media within 15 min after preparation of first dilution to avoid growth or death of microorganisms.
(b) Frozen eggs.—Thaw frozen egg material as rapidly as possible to avoid increase in number of microorganisms present and at temperature low enough to prevent destruction of the microorganisms (£45°C for £15 min). (Frequent rotary shaking of sample container aids in thawing frozen material. Thawing temperature may be maintained by use of H2O bath or bacteriological incubator.) Proceed as in (a).