NU FS363 Lecture Notes - Lecture 3: Diluent, Food Microbiology
1 Nov 2016
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Document Summary
Total counts are used to get an idea of the impact a specific species that may cause spoilage has on food safety. It is hard to identify specific pathogens so this type of count is used to give an idea about the number of microorganisms, not the diversity of them. To use the total count method you need at least 20 30 cfu/plate and a max of 300 cfu/plate for accuracy reasons. When a plate has between these numbers it can be counted. The cells are counted and then if dilutions took place you must multiple the # of cfu/plate by the dilution factor (ex. This method is a poor choice for samples that like to be cool because the media that is poured over the sample is 45 degrees. Celsius (to keep liquid form) and might hurt the cells of you sample. b)
