Effects of prefiltration and enzyme and surfactant treatments on the filterability of foods were examined. The clarification of food suspensions, using a fine wire cloth prefilter, did not affect microbial recovery from the 87 food samples examined. One hundred and nine foods were clarified by prefiltration and then tested for their filterability through a 0.45-μ Hydrophobic Grid Membrane Filter; 68 could be filtered without any additional treatment. Of the remaining 41 foods. 39 were rendered filterable with an appropriate enzyme or surfactant treatment. The application of these procedures greatly enhances the practicality of membrane filtration for microbiological analysis of foods.

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Author notes

1QA Laboratories Limited.

2Health and Welfare Canada.