Environmental Monitoring

We recently had an audit, and they said that we cannot have a range for E.coli testing for environmental testing in HZ1. We are a dry food manufacturing facility (cake mixes, flour, hot cocoa etc.) that uses indicator organisms for the testing process. The range we had was <10cfu or less and no greater that <20cfu. I am at a lost on what to do as this has been our standard for over 4yrs. and no other audit called it out. I have been looking for guidance and most say it is up to the company. 

Can anyone help us

Stacy 

You certainly do not want any E.coli in zone 1. However, I can see why your lab is reporting it <10 even when there is none on petri dish. It is due to dilution factor. 

Have you ever had any results that were not reported <10? You should specify your range as none or <10 in your guidance.

You could also ask your lab to test at a higher dilution, which then would result in <1 on your report when no growth detected.

I hope this helps! 

Hi Stacy,

Swab results should be reported in cfu/cm². It isn’t a massive issue to have a range as long as the standards are acceptable. I think the auditor may have been saying that you cannot have a range because E.coli should be ‘Not Detected’?

Clean surface standards are typically around:

TVC < 100 cfu/cm² Food Contact < 1,000 cfu/cm² target for other surfaces.

E.coli < 1 cfu/cm² Food Contact < 10 cfu/cm² target for other surfaces.

The standards are dependent on the area swabbed and the product. For high-risk RTE products and E.coli* positive on a food contact surface would need further action to ensure the product wasn’t contaminated.

* The infective dose of some E. coli for example O157:H7 is believed to be very low (10–100 cells).

For products that are meant to be cooked this is obviously far less serious.

For some useful background information on swab standards worldwide see the Micro. Guidelines for Food Contact Surfaces forum here where the late great Charles C posted a Compilation of International Micro. Guidelines for food contact surfaces, 2000 onwards. I think it is what you are looking for.

Kind regards,

Tony