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Understanding Food Sample Microbiology Results


Best Answer Charles.C, 02 August 2016 - 07:51 PM

Thank you for your response.  I will have a look at the link you suggested.  I would have enough background knowledge to understand text, in my degree I covered modules such as microbiology, food science and biochemistry. I asked the question as we had an abnormal micro result on a sample we sent to the lab, which came back with a high yeast count and presumptive entro.  All samples since have came back fine, but it has made me realise that I need to learn more about micro as I don't feel well enough equipped if another sample came back with unacceptable results .  I can't find practical information i.e.. what is the optimum temperatures for the oganisms to grow, what temperature can they be killed at, what is the main cause etc.

 

Thanks!

 

Hi walsh,

Thks reply.

 

Some comments –

 

Relevant temperature answers may relate to the type of food/species/matrix involved (unspecified).
Relevant micro answers may relate to the specific procedure/data involved (unspecified).

 

“Presumptive” is not a very meaningful term unless “negative”. Needs to be “Confirmed” if “Positive”.
“High Count” depends on the number/context.

 

Will need to give more details if further comments are of interest.

The typical initial approach to an unusual result if considered significant is to investigate production record / repeat (anon.) analysis same/similar lot if possible.

 

I have attached various refs below which should help to explain a lot of yr general queries. Hopefully  fairly understandable but please query if otherwise. The microbial kingdom is highly diverse, don't be too surprised if info. in different refs is not always in total mutual agreement.

 

Enterobacteriaceae
Members of the Enterobacteriaceae are small Gram negative, non-sporing straight rods. Some genera are motile by means of peritrichous flagella except Tatumella, Shigella and Klebsiella species which are non-motile. They are facultatively anaerobic and most species grow well at 37°C, although some species grow better at 25-30°C. They grow well on peptone and meat extract media. Some strains grow on D- glucose  as the sole source of carbon and energy, but other strains require vitamins and or amino acids. Acid is produced during the fermentation of D- glucose and other carbohydrates.

(mic5)

 

Yeast/Mould
The large and diverse group of microscopic foodborne yeasts and molds (fungi) includes several hundred species. The ability of these organisms to attack many foods is due in large part to their relatively versatile environmental requirements. Although the majority of yeasts and molds are obligate aerobes (require free oxygen for growth), their acid/alkaline requirement for growth is quite broad, ranging from pH 2 to above pH 9. Their temperature range (10-35°C) is also broad, with a few species capable of growth below or above this range. Moisture requirements of foodborne molds are relatively low; most species can grow at a water activity (aw) of 0.85 or less, although yeasts generally require a higher water activity.

(mic2)

 

 

PS - Please note that mic6 has some interesting comments on Enterobacteriaceae but data directly relates only to RTE foods.

 

Interesting to note what yr own situation is ?

.

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#1 walsh

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Posted 27 July 2016 - 10:34 AM

Hi, 

 

We use an outside lab to test are swabs and food samples weekly.

 

I was wondering if any one knew of a short e learning course or good text book that breaks each test down and explains what it is, what can cause it and possible preventative measures?

 

i.e:

 

Aerobic Colony Count

Presumptive Enterobacteriaceae

E.Coli

E. Coli 0157

Yeats 

Moulds

Listeria spp

Salmonella

Clostridia Spp

 

The reason I am asking is because we have received and unacceptable result this week for Presumptive Enterobacteriaceae and Yeasts and I'm overly knowledgeable regarding these,

 

Any help would be appreciated 

 

Thanks



#2 Charles.C

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Posted 27 July 2016 - 05:39 PM

Hi, 

 

We use an outside lab to test are swabs and food samples weekly.

 

I was wondering if any one knew of a short e learning course or good text book that breaks each test down and explains what it is, what can cause it and possible preventative measures?

 

i.e:

 

Aerobic Colony Count

Presumptive Enterobacteriaceae

E.Coli

E. Coli 0157

Yeats 

Moulds

Listeria spp

Salmonella

Clostridia Spp

 

The reason I am asking is because we have received and unacceptable result this week for Presumptive Enterobacteriaceae and Yeasts and I'm overly knowledgeable regarding these,

 

Any help would be appreciated 

 

Thanks

 

Hi walsh,

 

No offence intended but may i enquire as to yr technical background ?

 

Introductory texts in food micro. do exist but their "digestibility" will likely relate to above query.

 

I speak with some experience since my background is chemistry. TBH the micro. learning process so far has not been exactly "short" and is still ongoing.

 

 

You might try the list of items / Procedures in the (online) USFDA BAM manual since these all include a very readable introductory section but i would not claim the level is "basic".

 

http://www.fda.gov/F.../ucm2006949.htm

 

You might also, if not confidential, post yr specific problem data/product on the forum and some help will likely be forthcoming.


Kind Regards,

 

Charles.C


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#3 walsh

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Posted 02 August 2016 - 11:42 AM

Thank you for your response.  I will have a look at the link you suggested.  I would have enough background knowledge to understand text, in my degree I covered modules such as microbiology, food science and biochemistry. I asked the question as we had an abnormal micro result on a sample we sent to the lab, which came back with a high yeast count and presumptive entro.  All samples since have came back fine, but it has made me realise that I need to learn more about micro as I don't feel well enough equipped if another sample came back with unacceptable results .  I can't find practical information i.e.. what is the optimum temperatures for the oganisms to grow, what temperature can they be killed at, what is the main cause etc.

 

Thanks!



#4 Charles.C

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Posted 02 August 2016 - 07:51 PM   Best Answer

Thank you for your response.  I will have a look at the link you suggested.  I would have enough background knowledge to understand text, in my degree I covered modules such as microbiology, food science and biochemistry. I asked the question as we had an abnormal micro result on a sample we sent to the lab, which came back with a high yeast count and presumptive entro.  All samples since have came back fine, but it has made me realise that I need to learn more about micro as I don't feel well enough equipped if another sample came back with unacceptable results .  I can't find practical information i.e.. what is the optimum temperatures for the oganisms to grow, what temperature can they be killed at, what is the main cause etc.

 

Thanks!

 

Hi walsh,

Thks reply.

 

Some comments –

 

Relevant temperature answers may relate to the type of food/species/matrix involved (unspecified).
Relevant micro answers may relate to the specific procedure/data involved (unspecified).

 

“Presumptive” is not a very meaningful term unless “negative”. Needs to be “Confirmed” if “Positive”.
“High Count” depends on the number/context.

 

Will need to give more details if further comments are of interest.

The typical initial approach to an unusual result if considered significant is to investigate production record / repeat (anon.) analysis same/similar lot if possible.

 

I have attached various refs below which should help to explain a lot of yr general queries. Hopefully  fairly understandable but please query if otherwise. The microbial kingdom is highly diverse, don't be too surprised if info. in different refs is not always in total mutual agreement.

 

Enterobacteriaceae
Members of the Enterobacteriaceae are small Gram negative, non-sporing straight rods. Some genera are motile by means of peritrichous flagella except Tatumella, Shigella and Klebsiella species which are non-motile. They are facultatively anaerobic and most species grow well at 37°C, although some species grow better at 25-30°C. They grow well on peptone and meat extract media. Some strains grow on D- glucose  as the sole source of carbon and energy, but other strains require vitamins and or amino acids. Acid is produced during the fermentation of D- glucose and other carbohydrates.

(mic5)

 

Yeast/Mould
The large and diverse group of microscopic foodborne yeasts and molds (fungi) includes several hundred species. The ability of these organisms to attack many foods is due in large part to their relatively versatile environmental requirements. Although the majority of yeasts and molds are obligate aerobes (require free oxygen for growth), their acid/alkaline requirement for growth is quite broad, ranging from pH 2 to above pH 9. Their temperature range (10-35°C) is also broad, with a few species capable of growth below or above this range. Moisture requirements of foodborne molds are relatively low; most species can grow at a water activity (aw) of 0.85 or less, although yeasts generally require a higher water activity.

(mic2)

 

Attached File  mic1 - USDA introduction to microbiology for food processing.pdf   2.32MB   73 downloads

Attached File  mic2 - BAM - Yeasts, Molds and Mycotoxins.pdf   121.67KB   44 downloads

Attached File  mic3 - yeasts and moulds in food, Campden.pdf   121.33KB   50 downloads

Attached File  mic4 - Microbial Growth.pdf   215.86KB   51 downloads

Attached File  mic5 - UK Standard, Identification Enterobacteriaceae.pdf   928.55KB   56 downloads

Attached File  mic6 - Guidelines interpretation micro.results in RTE foods,GN3,rev2,2016.pdf   291.82KB   77 downloads

 

PS - Please note that mic6 has some interesting comments on Enterobacteriaceae but data directly relates only to RTE foods.

 

Interesting to note what yr own situation is ?

.


Kind Regards,

 

Charles.C


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#5 walsh

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Posted 03 August 2016 - 01:21 PM

Hi Charles, 

 

We deal only in ready to eat, cooked bacon.

 

Thanks so much for taking the time to post those links, I really appreciate your help.

 

I will get a good read at all of this information today. 



#6 liberator

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Posted 08 August 2016 - 10:14 PM

Some good information can also be found here: Bad Bugs 

 

http://www.fda.gov/F...ook/default.htm



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#7 walsh

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Posted 09 August 2016 - 01:17 PM

Thanks so much! This is all exactly what I was looking for  :spoton:






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