AOAC ERP MICRO AUGUST 2018

OMAMAN-44 A: Collaborative Study Manuscript Expert Review Panel Use Only August 2018

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autoclaved. Dispose according to local, state, and federal regulations.

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General Preparation

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( a ) Observe Good Laboratory Practices for microbial testing. Avoid specimen contamination.

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( b ) Test on a level surface, in a clean area, and free of dust and blowing air.

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( c ) Avoid hand contact with test samples and Peel Plate EB medium.

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( d ) Log serially dilute sample into BPW, Butterfields or microbiologically suitable water to obtain

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the countable range 1–154 coliform/mL or test multiple dilutions to attain the countable range. 154

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Sample Preparation

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Foods:

( a ) Add 25 g (25 mL if already liquid) of food (infant formula, butter, milk, ice cream, milk powder)

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to 225 mL of dilution buffer (BPW following ISO method), Stomach/homogenize for 1–2 min, let settle 1 160

min. Following homogenization, 1:10 serial dilutions are performed in dilution buffer to the desired 161

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concentration.

( b ) For cereal, add 25 g to 1225 mL of dilution buffer, Stomach/homogenize for 1–2 min, let settle

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1 min.

( c ) Continue to dilute 10 mL of prior dilution in 90 mL of dilution blank to reach countable range ERP Use Only (1 to 154 CFU/mL). Other volume/volume dilution schemes are acceptable. Surfaces:

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( a ) The sampling protocol followed ISO 18593 (8). Stainless steel surfaces were sampled by

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rehydration of a sponge with 25 mL BPW, rinsing aseptically, swabbing 100 cm surface and adding 169

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