8 replies to this topic

[2005PR]

Hi all,

 

There was complaint in cream and when we did yeast and mould testing, then orange colour colonies of yeast and black mould is detected.

Kindly help what colonies it could be and how can I confirm it apart from Microscopy?

[kconf]

I have more questions to ask you than you are asking 

 

Anyway, these are typical characteristics (orange yeast, black mold) of Y/M. Your lab should be able to identify. 

 

Was it over the limit? Did you have the product tested prior to receiving complaint? Was storage condition maintained throughout? 

[2005PR]

The sample was passed before.

The count is over the limit now. And the conditions we are not sure of as the complaint has come from single sample from someone's home.

[kconf]

So, a customer opened your product and found it to be moldy? 

[kingstudruler1]

I dont believe you can identify or speciate yeast with a microscope.   This is typically done using phenotype and / or genotype testing. 

Molds can be somewhat identified using miscropically.   However, one needs to have knowledge of the practice. 

In both cases, I think you need to send the organisms to an expert for identification if that is what you are wishing to accomplish.  

 

If your inhouse tests do not indicate an issue over the shelf life, I'm not sure what else you can do.   If you have an in house issue, you just need to find and eliminate the issue.  Doesnt really matter what the organisms are.  They need to be eliminated or reduced to an acceptable level.  

[Tony-C]

Hi 2005PR,

 

Assuming this is fresh cream, Y&Ms don’t survive pasteurization so contamination tends to come from the packaging or the environment. Given the product has a relatively short shelf life Y&Ms tend to be out competed by other organisms, although growth can be due to temperature abuse. So, if this is a one off complaint I wouldn’t worry about it.

 

If there is a trend in adverse results and complaints then try swabbing the packaging and doing some air exposure plates.

 

Kind regards,

 

Tony

 

[GMO]

Yeasts and moulds can survive pasteurisation.  Pasteurisation is a pretty gentle process.  But with chilling as well, the numbers are unlikely to be high.  Many cheese manufacturers in fact rely on a certain level of survival of non starter cultures to get the flavour they require but cheese maturation happens at a higher temperature at the levels you should be storing your cream at.

 

There are obviously lots of possibilities:

 

Survival via pasteurisation

Environmental recontamination post pasteurisation

Low levels of either the above which have grown due to temperature abuse

Post purchase contamination by the consumer

Inadequate sealing leading to post process contamination

 

Actions I'd suggest:

 

Ask your lab to ID it for you.  If not able, other labs can.  That will give you an idea if it's likely to have got through your pasteuriser.

Check your pasteuriser efficacy - not just temperatures but flow.  If you can, look for biofilms earlier than your pasteuriser as it might sound wacky but I have once heard of a biofilm breaking off and not being fully penetrated by the pasteuriser heat leading to fermentation.

Swab and air sample in your environment.

Test through the process.  Directly post pasteurisation, post pipework, post fill etc.

Check both sealing efficacy and if you have standard settings, if they're followed (if you don't, they're a good idea to have anyway even if your seals look good).

[Tony-C]

Yeasts and moulds can survive pasteurisation.  Pasteurisation is a pretty gentle process.  But with chilling as well, the numbers are unlikely to be high.  Many cheese manufacturers in fact rely on a certain level of survival of non starter cultures to get the flavour they require but cheese maturation happens at a higher temperature at the levels you should be storing your cream at.

 

There are obviously lots of possibilities:

 

Survival via pasteurisation

Environmental recontamination post pasteurisation

Low levels of either the above which have grown due to temperature abuse

Post purchase contamination by the consumer

Inadequate sealing leading to post process contamination

 

Actions I'd suggest:

 

Ask your lab to ID it for you.  If not able, other labs can.  That will give you an idea if it's likely to have got through your pasteuriser.

Check your pasteuriser efficacy - not just temperatures but flow.  If you can, look for biofilms earlier than your pasteuriser as it might sound wacky but I have once heard of a biofilm breaking off and not being fully penetrated by the pasteuriser heat leading to fermentation.

Swab and air sample in your environment.

Test through the process.  Directly post pasteurisation, post pipework, post fill etc.

Check both sealing efficacy and if you have standard settings, if they're followed (if you don't, they're a good idea to have anyway even if your seals look good).

 

You are wrong GMO and your post doesn't appear to be based on experience, Y&M very rarely survive pasteurisation. I don't think I've ever seen a Y&M count in fresh pasteurised cream off the pasteuriser, if there has been a count it was usually from a contaminated sample point.

 

Pasteurisation kills most heat-sensitive microorganisms such as yeast or mould fungi

At the same time, however, a few germinating bacterial spores can remain. Pasteurised foods are thus not germ-free, but only germ-poor. They are therefore limited in durability.

 

Kind regards,

 

Tony

Edited by Tony-C, 10 July 2025 - 07:03 AM.

[GMO]

There are some fungal species which can survive Diversity and Control of Spoilage Fungi in Dairy Products: An Update but also if there are biofilms as I described, you can also have broken off pieces where the heat does not penetrate.  

 

I didn't mean to imply it was common, rereading I probably worded it badly but it does happen however, I agree, post process is more likely.