Is it Acceptable to Alter Yeast & Mold Testing from 5 Days to 3 Days?
I am not sure I am in the right section. My lab manager wants to change the yeast & mold testing to a 3-day count only. I've explained that it should be 3 and 5 day but, I am getting nowhere. He says he started a validation study and used Statistical Process Control and we can read plates at 3 days only, we don't need to wait for the 5 day count. This is an AOAC-RI method.
FDA BAM is generally 5 days incubation for Y/M. However, certain food products do qualify for a 3 day period (need validation). Also, there is rapid yeast mold petri film method that is 2 days.
For chocolate specifically, there is a compact dry method - 3 days.
But the FDA method itself cannot be altered. It says to incubate for 5 days and even incubate additional 48 hours if needed.
I hope this helps!
Thank you for the info.
We are using a Peel Plate which, from information and the website state that "YM tests produce spots that are quantified over the 3 to 5 day incubation"
This is for soft cheeses, mozz and ricotta. And we have typically read plates at 3 and 5 days. I reached out to our supplier who returned a message from the manufacturer that they recommend reading at 3 and 5 days. But, he still wants to do just 3 day because "earlier results are most advantageous and allows us quicker response". My response was that he could be missing counts if he forgoes the 5 day count. I don't know what else to say.
Your lab manager is correct then. They can be read at 3 days.
Thank you for your input but I am still puzzled by this as we read both 3 day and 5 day. We had done a 3-day vs 5-day comparison about 5 years ago and the results showed that 5 days would give us higher results or no change. Why would we leave out the 5-day count to go with only a 3-day?
Because the parameters are matrix based. How greatly have your results varied?
I don't have the paperwork; I would need to hunt it down but I am not in that area anymore.
From memory...I believe it was just shy of 400 samples. I can't say much definitively other than there were so many more with counts or higher counts at 5 days. This was at a time when we had a mold problem.
To clarify -
* we use Peel Plates that are read at 3 and 5 days
* our samples are mozzarella and ricotta cheese
* they want to end counting the Y&M plates on day 5
I have reached out to Charm Science and Cornell University. Both are stating that we should read at 3 days and at 5 days
My comments are, if they want a 3-day Mold result, then we should switch to a Rapid Yeast & Mold rather than taking only the 3-day read and missing out on the results from the 5-day read.
The incubation period is 3 to 5 days, not necessarily to be read at both 3 and 5 days. It is not going to be a difference of day and night.
If you count 423 colonies at day 3, and 753 at day 5, they are are not any different. There are both within the same log.
Don't overstress yourself and enjoy, let them enjoy the cheese :D
^So many typos, won't let me edit. They are*.
:spoton:
Here, 4230 and 7530 are huge.
Our limit is 100 cfu/g so a difference between 80 and 180 does mean something. I gave them my opinion and that's all I am required to do. I don't make the decisions.
But thank you for the idea! Wine and cheese sounds wonderful - I have a wedge of French cheese that I bought recently that I am dying to try!
And thank you everyone for your so prompt and wonderful replies. I actually thought it would be days before I had a reply. Nice to know someone is out there.
Have a great day all!
4230 and 7530 are not different, again same log.
4230 and 12451 would be different, because you are moving up a log.
Having set the limit to <100 and getting 80 might be acceptable, but it does tell you that the product is moldy and needs to be monitored.
I'm sorry. I didn't say they were different. I said Huge, for us.
I didn't mean anything...
Our clients request <100 cfu/g mold and we give them COAs
So, over 100...
Mold is common due to the high temperatures and very wet processing areas. Keeping it down is important.
We do air plates, once monthly except for summer when we do every other week.
Like I mentioned, not my decision but following laboratory protocols strictly is what was ingrained in me. It happens when you work in research.
Things are a bit looser (quite a bit at times) in the food industry. But I have my habits. I guess I don't want to let go of them.
I do intend to go home and enjoy a nice wine (local winery) and a cheese I found at a wonderful store about 2 hours from home.
Please, have a wonderful day. And I thank you for your information and conversation. I enjoyed it.