Microbial growth in dry sugar/salt product

Hi All,

My company co-packs various dry powders and we 3rd party lab test finished packets.

We had a sugar/salt drink mix product come back with 1500 TPC, when all other lots had zero. We retested retains on bulk and finished packets for the lot and had zero again. But asked the lab to retest their retain from the first test and it came back with 150,000 TPC confirming positive bacterial contamination.

My question is does this new test indicate growth and what could possibly grow under the conditions of the particular product? The only results we've gotten with products having 100,000+ TPC were probiotics, and this product was ran on different lines.The manufacturer of the product doesn't produce probiotics. 

The lab insisted there was no issue with contamination on their end, but is it possible?

Thank you!

Hi, aaallen. 

You may want to test samples with high TPC for analysis intended for probiotic analyis. In this way, probiotic will be inhibited to grow in TPC plates (or petrifilm), if it does not exceed your limit on this analysis, then your sample can be contaminated with probiotics either thru handling of packing. If the samples still exhibited high TPC count, then look back on your process as well (including lab).

Btw, is the time stamp of your sample different from what you sent in your 3rd party analysis? e.g. 3rd party sample is within 1st hr of production and your sample can be in the last hour.  Depending on the probable cause, the TPC distribution may not be equal for the whole lot. 

Thank you, I didn't know we could do analysis that would inhibit growth of probiotics in plates, I'll inquire at our lab. 

The contaminated sample sent to the lab and our retain sample that subsequently tested zero were from the same time stamp in the lot, which is why it's so confusing to have the lab results so different.

Hi Aaallen,

That could be a testing error.  We had several incidents where labs switched samples by mistake.   

Sincerely