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#1 Inverse

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Posted 21 June 2017 - 07:37 AM

Hi all,

 

Since microbiology is not my strongest area, I'm asking for your help (again).

 

So I've sent some samples of our raw and dried product (we produce dried vegetables). I was expecting to see higher ACC colony count in raw sample than dried but it was other way around! It is still within the limits but ACC was <10cfu/g in a raw sample and way more in already dried. Do you have any ideas why it happened? I'm trying to collect as much information as possible to understand how this happened and prevent it to happen again.

 

Any kind of information is much appreciated! 

 

Thank you.

 

P.S. Your forum is the best! I don't know what I would do without it. Thank you all   :smarty:   :thumbup:



#2 Charles.C

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Posted 21 June 2017 - 07:50 AM

Hi all,

 

Since microbiology is not my strongest area, I'm asking for your help (again).

 

So I've sent some samples of our raw and dried product (we produce dried vegetables). I was expecting to see higher ACC colony count in raw sample than dried but it was other way around! It is still within the limits but ACC was <10cfu/g in a raw sample and way more in already dried. Do you have any ideas why it happened? I'm trying to collect as much information as possible to understand how this happened and prevent it to happen again.

 

Any kind of information is much appreciated! 

 

Thank you.

 

P.S. Your forum is the best! I don't know what I would do without it. Thank you all   :smarty:   :thumbup:

 

Hi Inverse,

 

An APC  result of <10 cfu/g sounds almost unbelievable for a raw vegetable. Has it been soaked in hypochlorite ?. Or is it naturally very high acid ?

 

How was the drying done ? In the Sun? :smile:


Kind Regards,

 

Charles.C


#3 Inverse

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Posted 21 June 2017 - 08:08 AM

Hi Charles,

 

In this case it was sea vegetable and it wasn't soaked in hypochlorite. 

 

Product is dried in a dryer and then moved to large tote bins. Do you think it might be the case of cross-contamination due to handling? 

 

Thank you!



#4 Charles.C

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Posted 21 June 2017 - 08:26 AM

Hi Charles,

 

In this case it was sea vegetable and it wasn't soaked in hypochlorite. 

 

Product is dried in a dryer and then moved to large tote bins. Do you think it might be the case of cross-contamination due to handling? 

 

Thank you!

 

Hi Inverse,

 

Ahh. This item appears to be a bit special.

 

Attached File  sea vegetable.pdf   1.02MB   27 downloads

 

Even so, <10cfu/g is low/very low (see pg 53).

 

What is yr target maximum ?

 

"Contaminated"  depends on what yr final results were. hopefully not based on one sample. Plate count data tends to be "scattered".

 

Dried at what temperature and for how long ? (approx.)


Kind Regards,

 

Charles.C


#5 Inverse

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Posted 21 June 2017 - 08:34 AM

Hi Charles,

 

Thank you, I've contacted our lab to get some more information and I'll send another sample. The good thing is that the result is still acceptable but it just raises some questions... 

 

Do you think it depends on drying time and temp? We are for about 3.5h at approx. 40 deg C (core temp). 



#6 Rener De Jesus

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Posted 21 June 2017 - 08:35 AM

Have you re-tested your raw vegetable or your dried product? Based on my experience in microbiology testing of raw vegetables, less than 10 CFU/g is unbelievable unless the sample was previously treated to lessen microbial count. While most dried products have no microbial count, if the process, e.g temperature and time, and handling were properly applied throughout the production.

If you did the retest and the result is still the same. Maybe there's a problem in handling or processing of the finished product.

I hope your controls were okay.



#7 Inverse

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Posted 21 June 2017 - 08:44 AM

Have you re-tested your raw vegetable or your dried product? Based on my experience in microbiology testing of raw vegetables, less than 10 CFU/g is unbelievable unless the sample was previously treated to lessen microbial count. While most dried products have no microbial count, if the process, e.g temperature and time, and handling were properly applied throughout the production.

If you did the retest and the result is still the same. Maybe there's a problem in handling or processing of the finished product.

I hope your controls were okay.

Hi,

 

Thanks for your reply. I just received the results and was a bit confused, so I'll send some more samples today to double-check. 



#8 FurFarmandFork

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Posted 26 June 2017 - 07:10 PM

Another, far simpler, explanation would be simply that more microbes are represented in your dried sample than your wet sample because it's much less dense. E.g. 10g of wet peas may be 2-3 peas, 10g of dried peas may be 10-12 peas and all of the organisms represented on their surfaces. When vegetables are dried moisture can account for 70-90% of the weight of the product. So results in CFU/g will naturally represent more "non water" material.


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Owner/Consultant at Fur, Farm, and Fork.
Consulting for companies needing effective, lean food safety systems and solutions.

Subscribe to the blog at furfarmandfork.com for food safety research, insights, and analysis.

#9 Charles.C

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Posted 27 June 2017 - 02:39 AM

Hi 3F,

 

I theoretically agree with you but IMO the fundamental problem is that one sample proves nothing, unless it's a positive for Salmonella. :smile:

 

I also noted that 40degC is a quite nice growth temperature for mesophilics but 3.5hrs is maybe a bit limiting if one includes a time lag. I was also surprised it achieves "dryness" unless there is some forced ventilation involved.


Kind Regards,

 

Charles.C





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