We usually perform APC testing on milk on the 15th day of bottling (end of shelf life). We are consistenly getting higher APC counts, however first day tests doesnt show anything abnormal. We suspect the presence of biofilms/ psychotrophs? Could someone suggest some ways to identify the presence of such organisms?
Hi Antony...
Technically, for milk and dairy foods Standard Plate Count (SPC) term is used instead of APC. These two reference methods differ in their temperature of incubation. For APC plates are incubated at 35ºC and for SPC incubated at 32ºC. As you pointed out ....Biofilms could be a source for the high counts. Psychrotrophic bacteria might be getting dominant after incubation in the later stage.
Usually we get a heavier microbial growth on 15th day, but it is never Too Numerous to Count. Now we are consistently getting such growth for every product.
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