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Enterobacteriaceae and shelf life of pasteurised milk


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Nitram V

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Posted 02 July 2017 - 10:54 PM

I have enterobacteriaceae < 10cfu/ml at production stage however the same batch at end of life come in at 390 - 1500 cfu/ml.  These results fall into Public Health England 'borderline' status but what I need to understand is how the to interpret this?



Rener De Jesus

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Posted 02 July 2017 - 11:32 PM

Hi Martin. What is the storage temperature of your samples until the end of shelf life? I think, if the results are within the "borderline", it will not impose any issue/s as long as there are no pathogen present.



Nitram V

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Posted 03 July 2017 - 07:56 AM

Samples are handled by external lab, end of life sample held at <5C for shelf life period and then at ambient for 2hrs (typically 18C) prior to plating.

 

I suppose at start of life there could be 9 colonies and hence we comply with Microbiological Criteria EC 2073/2005 at production stage <10 cfu/ml and duly they multiply over the shelf life period.



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Posted 03 July 2017 - 05:15 PM

Do you do EB testing on your packaging? That could be the source of the "seed organisms" leading to the eventual growth at end of life.

 

I would be concerned with "borderline" status in your controlled lab conditions, simply because "real life" is going to have warmer refrigeration and non-aseptic handling. Ideally your product performs great in the lab setting to allow for abuse.


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Charles.C

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Posted 04 July 2017 - 02:33 AM

Hi Nitram,

 

I'm not sure where yr limits come from ? i see -

 

Attached File  pasteurized milk enterobacteriaceae.png   94.63KB   8 downloads

 

added - OK i see uk are much more lenient than EC -

 

Attached File  pasteurized milk UK enterobacteriaceae.png   40.05KB   7 downloads

 

So what is the shelf life test period ? What is the "ambient temperature" mentioned ? heatwave ?

 

Where does yr "borderline" comment numerically derive from ?  (although offhand, the final values look high relative <10 cfu/ml).

 

Maybe the sample was mishandled prior start shelf life test, do your lab graph of Entero vs time across shelf life test period ?

 

I also noticed this comment -

 

Attached File  pasteurised milk (stored) enterobacteriaceae.png   112.03KB   3 downloads


Kind Regards,

 

Charles.C


Nitram V

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Posted 05 July 2017 - 08:37 AM

Do you do EB testing on your packaging? That could be the source of the "seed organisms" leading to the eventual growth at end of life.

 

I would be concerned with "borderline" status in your controlled lab conditions, simply because "real life" is going to have warmer refrigeration and non-aseptic handling. Ideally your product performs great in the lab setting to allow for abuse.

No testing on packaging, yes it could be.

 

Borderline status comes from Public Health Department guidance taken from a study of pasteurised milk from retail outlets and we all know how they can treat chilled products.  Lab conditions prevail for shelf life product with 2 hrs abuse at ambient.  Temperature abuse takes many forms outwith lab conditions and to cover all would be unrealistic.  On another note the Aerobic count was acceptable.

 

Thanks



Nitram V

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Posted 05 July 2017 - 09:24 AM

Hi Nitram,

 

I'm not sure where yr limits come from ? i see -

 

attachicon.gifpasteurized milk enterobacteriaceae.png

 

added - OK i see uk are much more lenient than EC -

 

attachicon.gifpasteurized milk UK enterobacteriaceae.png

 

So what is the shelf life test period ? What is the "ambient temperature" mentioned ? heatwave ?

 

Where does yr "borderline" comment numerically derive from ?  (although offhand, the final values look high relative <10 cfu/ml).

 

Maybe the sample was mishandled prior start shelf life test, do your lab graph of Entero vs time across shelf life test period ?

 

I also noticed this comment -

 

attachicon.gifpasteurised milk (stored) enterobacteriaceae.png

Thank you.  EC 2073/2005 was amended by EU 365/2010 as method was difficult to work with, costly,  and thus now <10 cfu/ml and not <1/ml.  I don't believe this amendment was down to UK leniency.

 

The borderline comes from PHA Guidance (currently undergoing review):

 

http://webarchive.na...C/1259151921557

 

Public Health England conducted a survey of pasteurised milk form retail outlets using the PHA criteria which made for some interesting reading.  However I wish I had saved a copy as I appear no longer able to find it online.

 

Lab not asked to monitor enteros v time, only SOL and EOL.

 

Down to dealing with root cause.

 

Thank you.



Charles.C

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Posted 05 July 2017 - 10:06 AM

Hi Nitram,

 

I deduce the sampling/sample control was not done by you.

 

Was the data based only on one sample ? I hope not.

 

Need minimally sample at W entero. >  X days storage >  Entero. value Y. Followed by 2 hrs ambient >Z..

 

I suspect you simply need more data to get much further. And surely more samples if only one.

 

i got the EC data from here -

 

https://www.afbini.g...on-no-1441-2007

 

looks like UK cannot keep up with EC publications.

 

I am guessing the UK  "borderline" came from the official HPA publication ca 2009-10 which is 100-10,000 cfu/g and linked to -

 

Possible evidence of poor hygiene due to undercooking, or cross contamination from raw meat, food handlers or food contact surfaces as well as poor temperature and time control.

 


Kind Regards,

 

Charles.C


Charles.C

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Posted 05 July 2017 - 10:20 AM

addendum - sorry i missed yr pdf link which is to same document as i quoted.


Kind Regards,

 

Charles.C


Charles.C

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Posted 06 July 2017 - 02:55 AM

Hi David,

 

You may be interested in these (2016) comments from the FSAI’s  RTE Foods Microbiological Guidelines in which they have taken issue with the HPA’s Guidelines (vis-a-vis EC) for various Micro. Species/Groups/Food Categories –

 

(Extracted from Introduction)

While the Food SafetyAuthority of Ireland’s (FSAI’s) Scientific Committee endorsed  the use of the UK’s 2009 guidelines, they also provided a Scientific Opinion (Appendix 2) on the appropriate microbiological guidelines to set for coagulase-positive staphylococci, E.  coli and Enterobacteriaceae, for which there was a discrepancy between guideline limits set  in the first edition of Guidance Note No.3 and in the UK document, and legal process hygiene criteria set in Commission Regulation (EC) No 2073/2005, as amended.

 

 

(Extracted from Scientific Opinion)

3. Enterobacteriaceae

Discrepancy: Guideline limits for ready-to-eat foods sampled at point-of-sale [ie HPA] are considerably more lenient than the legal limits applicable during manufacturing [ie EC] for six categories of food (Table 5).

 

1.  Pasteurised milk and other pasteurised liquid dairy products (food category: 2.2.1)

Etc

 

 

Question: Is it appropriate to set Enterobacteriaceae guidelines for the six food lists and if yes, what should these guidelines be?

 

Proposed answer: No.

Limits for Enterobacteriaceae at retail level should not be set for these six food categories. Enterobacteriaceae are a broad group which can be used to assess the general hygiene status of a food  product. Unlike E.coli, Enterobacteriaceae  are not a clear indication of  faecal  contamination  and  there is no level of Enterobacteriaceae  which can be classified  as hazardous.

 

 

(There is a similar but “inverse” criticism for E.coli, but in this case FSAI have quantitatively modified the HPA values)

 

Attached File  FSAI,GN 3 Rev 2, 2016.pdf   291.82KB   20 downloads


Kind Regards,

 

Charles.C


Tony-C

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Posted 06 July 2017 - 12:03 PM

I have enterobacteriaceae < 10cfu/ml at production stage however the same batch at end of life come in at 390 - 1500 cfu/ml.  These results fall into Public Health England 'borderline' status but what I need to understand is how the to interpret this?

 

Hi Nitram,

 

You are getting contamination and you need to find the source.

 

I would try additional more sensitive testing, per 1ml, per 5ml (14cm plate) or incubating the sample prior to analysis.

 

Kind regards,

 

Tony



Ryan M.

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Posted 06 July 2017 - 02:31 PM

Hi Nitram,

 

You are getting contamination and you need to find the source.

 

I would try additional more sensitive testing, per 1ml, per 5ml (14cm plate) or incubating the sample prior to analysis.

 

Kind regards,

 

Tony

 

I agree with Tony here.  You have a low level of contamination coming from somewhere.  Possibly the packaging, but honestly I doubt that.  I think you have an environmental sanitation problem (inconsistent) or a problem with one of your CIP systems (I'm assuming CIP since you are talking dairy).

 

The first step is to do more testing of finished product off your packaging fillers.  I would suggest, for the sake of time pre-incubate the samples.  You can also do side by side testing with pre-incubated and then samples that are not pre-incubated.

 

What is the normal shelf-life you are putting (days code) on the milk?  Are you packaging in cartons, bottles, both?



Tony-C

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Posted 06 July 2017 - 03:13 PM

Hi Nitram,

 

To add our posts above, based on experience the most likely source of contamination is the filling equipment so an indication of what filling equipment you are using will help.

 

Kind regards,

 

Tony






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