4 replies to this topic

[KevinMc]

Hi All, 

 

Would anyone have any advice on the best methods for testing for yeasts & moulds within products please? 

 

We are seeing high results when using Orange Serum Agar, but nothing is showing when Dichloran Rose-Bengal Chloramphenicol (DRBC) is used.

 

The product has small amounts of some citrus juices in (Lime & Orange), approx 0.3%.  The rest is made up of spring water, preservatives and some flavourings. 

 

The product is also pastuerised, yet we are still seeing high results.  Every other product we produce does not have an issue, only the ones with the citrus juices in.  We have tested the raw material and that has came back as clean, so I am at a loss as to what may be causing these issues.

 

Thanks in Advance

[kingstudruler1]

OSA is not selective for yeast and mold - used for bacteria as well..  The Chloramphenocol in the DCRB makes it selective for yeasts and mold (limits bacteria)

 

 

What are the final products?   are these all low ph products?

 

what are high results?

 

you have issues straight out of the pasteurizer?   All ingredients are tested?

 

temp / time?

 

im sure others will have more questions as there are a lot of variables to consider.   

Edited by kingstudruler1, 05 September 2023 - 07:55 AM.

[KevinMc]

Thanks for the response.

 

The final product is a carbonated flavoured water.  The high results are >101 per 100ml for yeasts & moulds.  The product is pasteurised and the set point 75°C for 30 seconds.  The PU readout on the day was 246. 

[KevinMc]

Apologies, the pH is between 3 & 3.5

[Charles.C]

Hi All, 

 

Would anyone have any advice on the best methods for testing for yeasts & moulds within products please? 

 

We are seeing high results when using Orange Serum Agar, but nothing is showing when Dichloran Rose-Bengal Chloramphenicol (DRBC) is used.

 

The product has small amounts of some citrus juices in (Lime & Orange), approx 0.3%.  The rest is made up of spring water, preservatives and some flavourings. 

 

The product is also pastuerised, yet we are still seeing high results.  Every other product we produce does not have an issue, only the ones with the citrus juices in.  We have tested the raw material and that has came back as clean, so I am at a loss as to what may be causing these issues.

 

Thanks in Advance

Hi Kevin,

 

Y&M not my area of expertise but yr OP/Post3 are slightly confusing.

 

I deduce from Post 2 that the agar used for "high" results is non-selective so yr data 101/100ml wud appear to be of limited meaning for Y&M ?

 

Doesn't explain why the actual 101cfu/100ml is obtained of course. My first response wud be to repeat the measurement. [offhand 1/g does not seem particularly "high"]

 

PS I am rather curious how you get 101 cfu presumably from a direct 1ml sample on an agar plate or is this perhaps a MPN or membrane Procedure (Not 10¹ by any chance ??)