Hi, Gelato.
I supposed the inquiry is for Ice cream plant. You could also look check in reverse or isolate the issue..
1. When you perform pre-cleaning test, how long is the time for cleaning?
2. Is the post-cleaning sampling waited so the samples are sent as one?
3. How long is the sample being stored, sent and analyze?
The reason for the above is the post cleaning "could be" the accurate one and the microbes being sampled for pre-cleaning may not be handled ideally to preserve the sample.
4. How is the start-up products microbial profile? Are they within norms?
The reason being for dirty equipment (assuming this the one that the product constantly flow to), the profile for the product should have high microbial count for the very first product out and the count decreases over time (unless gross contamination or the equipment swap being question is used for storage or the equipment being question is pre-storage pipe or line)
Should you be confident on the above the you may want to have your chemicals be sampled for micro and check the swabbing practices.
1. Have one experience before but on handswab that we are getting high APC after hand swab. We requested parallel check with the supplier and we outsource one and the hand sanitizer chemical have TNTC count on all 3 tests. We immediately replaced to alcohol as alternative hand sanitizer.
2. Sampling can very well impact results. Is it sampled wet? Is it sampled dry? Have you sampled finishing the required contact time? Sampled the same sampling point? Are the sampling tools used fit for the environment or product?
3.Lastly, it could also be the cleaning techniques are the one causing the high micro, have you observed the cleaning techniques? Sampling results are always a lagging indicator. We can take 10, 100 or 1000 samples but if cleaning techniques were not observed, we will just have to wait for the results assuming cleaning follows all parameters.