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How to control coliform in cheese manufacturing


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#1 Lean z

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Posted 03 June 2012 - 11:02 AM

I recently joined a cheese manufacturing, making fetta cheese, most of the rejects here are due to coliform. Fetta cheese have been brined for min 7 days, but after packing, sometimes the result for coliform are more than 1100 cfu/g. The swobs shows me minimum counts but finish products are disaster. Help!!



#2 Charles.C

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Posted 05 June 2012 - 05:03 AM

I recently joined a cheese manufacturing, making fetta cheese, most of the rejects here are due to coliform. Fetta cheese have been brined for min 7 days, but after packing, sometimes the result for coliform are more than 1100 cfu/g. The swobs shows me minimum counts but finish products are disaster. Help!!


Dear lean z,

Thank you for yr query.

Unfortunately i am not familiar with process fetta cheese however there are a few basic routine items of info. which IMEX I and other people (unless they [luckily] recognize yr problem directly) will prob. also need, eg

1. Is this a new problem within a long time manufacture with no problem. If so, usually implies something changed "somewhere". Or is this a new start-up operation. ?

2. Assuming new problem, Is micro quality of inputs checked and seems normal ?

3. Change in process ? Established procedure for coliform measurement on finished product ?

4. Rejection due coliform is common problem in manufacturing of fetta. ?

The swobs shows me minimum counts



What does this mean ? Cleanliness of equipment ?

I can prob. access some process data / answers, eg No.4 on the net but quicker to ask regarding yr specific situation. :smile:

Rgds / Charles.C

Kind Regards,

 

Charles.C


#3 Lean z

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Posted 13 June 2012 - 01:06 PM

Hi Charles, thanks. High coliform counts is existing problem here quite a long time, and never been solved. By swob test, I mean the environmental micro test. I Am not sure if I should concentrate on human contamination or process.



#4 retep

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Posted 13 June 2012 - 03:01 PM

I'm not by any means an expert in this area but have you conducted water microbiology tests ?



#5 Snitzel

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Posted 15 June 2012 - 12:36 PM

From the top of my head...

Logically you are pasteurising the milk you are using... are the time/ temperature conditions OK (ie 72C/15secs or equivalent)?

are the temperature probes calibrated?

do you get coliform counts after pasteurisation?
Are your fermentation cultures controlled? did you check the culture for coliforms?

If heat treatment and the fermentation cultures are OK then you should focus on proper cleaning and possible contamination from insufficient cleaning/ sanitation (including personnel)



#6 Charles.C

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Posted 15 June 2012 - 02:18 PM

Dear leanz,

Thks for yr response.

I also suggested that knowledge of the process might be necessary.

After previous post and a little googling, I see that feta can be produced with or without a pasteurisation step.

The subsequent micro. characteristics can, not surprisingly, be highly related to the option used.

So which is it ? :smile:

Rgds Charles.C

PS -
1.If it is (properly) pasteurised milk, this 1st clip from a 1987 publication might be interesting to you plus the 2nd extract below from another study -
(sorry, uploader seems not working for me at moment)

2.

Minimizing exposure to the environment, good sanitation, fast cooling to 40 F, tight packaging, and storage at 38 F or less helps to minimize the growth of coliform bacteria


PPS - I hope I am wrong but i hv a distinct suspicion that this product will turn out to be non-pasteurised. :smile:

Kind Regards,

 

Charles.C


#7 Tony-C

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Posted 17 June 2012 - 01:14 PM

I recently joined a cheese manufacturing, making fetta cheese, most of the rejects here are due to coliform. Fetta cheese have been brined for min 7 days, but after packing, sometimes the result for coliform are more than 1100 cfu/g. The swobs shows me minimum counts but finish products are disaster. Help!!


Hi Lean z

You need to provide more information about your process.

Such high numbers in products and low counts from swabs would indicate low level contamination at the incubation stage leading to multiplication of the coliforms before the final & correct pH is reached.

Regards,

Tony

#8 Saurabh

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Posted 19 June 2012 - 01:49 PM

Hi Lean z,
Getting coliforms in your final cheese product is a very serious problem. There are two possiblities, one is improper pasteurization and second post processing contamination.
To determine the source of contamination, you will need to do a line study. You should be sampling the product/intermediate product at each and every step. For e.g. raw milk (raw cream, skim milk, skim milk powder etc.), after pasteurization, before adding culture and enzyme, after culture and enzyme, before cutting, after cutting, Whey draining step, at salting stage, milling stage, pressing stage, etc. and conduct micro analysis, specifically coliform detection. Please do all these test for same batch/lot no. An enumeration of SPC and coliforms will also help to determine if the counts are increasing or decreasing at subsequent stage.
I would also suggest you to do surface swabs of all the equipments being used for cheese manufacturing. i.e. all the equipments coming in direct contact with product just before using them for production.
It would also be benificial to conduct micro analysis for ingredients like Calcium Chloride, salt, enzyme, starter culture, colour (if being used), packaging material etc.
All these steps would give you a broader picture of your processing steps in context to contamination of your product and a detailed analysis of test results will help you to implement control measures to prevent contamination.
Coliform in final cheese product will give you bad quality of cheese and will hit hard on the profit of your company.
Hope you are able find and fix the problem as soon as possible.


I recently joined a cheese manufacturing, making fetta cheese, most of the rejects here are due to coliform. Fetta cheese have been brined for min 7 days, but after packing, sometimes the result for coliform are more than 1100 cfu/g. The swobs shows me minimum counts but finish products are disaster. Help!!



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#9 Gunapathi

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Posted 20 June 2012 - 08:30 PM

Hi,
Based on my experience, potential source of contamination could be the cheese draining clothes. When we had this problem, we tried several methods of sanitising the clothes, but at last we used a washing machine to do a hot wash without any chemicals and it resolved the issue.
Might suggest to give a try.
Other source could be your brine solution.
Human contamination is possible, but very unlikely to be at this high count in fetta process.
Hope this helps.



#10 warrior

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Posted 08 November 2012 - 10:15 PM

Your problem can be due to two reasons.
1.-A crack in your vat/kettle.
swab test will be fine because that crack will only release dirt when you turn the heat on you vat.
the heat will expand the crack and dirt will get in your milk.

You can inspect your vat by:
-very detailed check by naked eye
-fill the vat with water and turn steam on to check for bubbles
-if your vat is inclosed use a black light to find the crack.

Hope this help you

MD



#11 Tony-C

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Posted 09 November 2012 - 06:22 AM

Your problem can be due to two reasons.
1.-A crack in your vat/kettle.
swab test will be fine because that crack will only release dirt when you turn the heat on you vat.
the heat will expand the crack and dirt will get in your milk.

You can inspect your vat by:
-very detailed check by naked eye
-fill the vat with water and turn steam on to check for bubbles
-if your vat is inclosed use a black light to find the crack.


2.-Dirty molds


The problem could be caused by many things, sound advice from Saurabh earlier in the forum here

Molds you can identify quite easily and you would see in the product? if they survived.

You have made an assumption that there is only one vat and it is steam jacketed? It would be a miracle if you managed to find cracks/pinholes in vats visually.

For detection of cracks/pinholes dye penetration works quite well. Example here http://www.alliancef...ce/tank-testing

Regards,

Tony




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