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Shelf life studies with cooling chain breakage


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#1 Nove

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Posted 05 June 2018 - 09:40 AM

Good morning.

 

 

I am looking for some guide regarding shelf life determination. Precisely I need some advice about cooling chain breakage?
as You certainly know cooling chain is expected to be broken as goods are carried from shop to customers’ house.

Is there any guide that can explain how to carry out these kind of microbiological shelf life tests?

For example how long food should be kept at higher temperature? What temperature it should be?

I have only found some general information that test have to be carried out under realistic conditions which mirror resonably, foreseeable conditions of storage, distribution and use.

I need more detailed infomation to know how to plan shelf life test (not challenge test)

I would be greatful for help.



#2 Tony-C

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Posted 05 June 2018 - 11:29 AM

Hi Nove,
 
I have seen many different protocols used, many are based on customer/retailer requirements.
 
I presume that you mean for chilled products.
 
A stringent regime would be 8 °C +/- 1 for life with a 4 hour exposure to ambient temperatures at some stage during the shelf life.
 
Other regimes reflect the anticipated chill chain temperatures such as x days at say 3-5 °C to represent while product is in your control then Y days at 8 °C +/-1 when it is with the retailer/customer etc.
 
Kind regards,
 
Tony


#3 Nove

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Posted 05 June 2018 - 12:15 PM

Hi Tony

 

Thank you for your reply.

 

Yes, I meant chilled product (ready to eat meat products) with recommended storage temperature max +5 C.

 

"A stringent regime would be 8 °C +/- 1 for life with a 4 hour exposure to ambient temperatures at some stage during the shelf life" do you have the source of this protocol? Where can I find it?

 

I have to submit to our veterinary office that it was made on the basis of specified guidelines. 

 

Best Regards,

Monika



#4 Tony-C

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Posted 05 June 2018 - 12:43 PM

Hi Monika,
 
Some people will say you should base your shelf life protocol on the storage temperatures you prescribe for your product, but these temperatures may not be realistic when the product is in the market.
 
The 8°C was based on my experience in major projects to extend the life of dairy products in the UK and based on UK temperatue control requirements: http://www.legislati...schedule/4/made
 
Here the authority prescribes 5°C and 'under conditions of mild temperature abuse', I for one am not sure what temperature 'mild temperature abuse' is exactly:
Initial studies are likely to consist of storage trials under the recommended storage conditions. Refrigerated storage trials should be run at 5°C and under conditions of mild temperature abuse equal to what might be encountered in the commercial cold chain.
http://www.foodautho...ife_testing.pdf
 
Kind regards,
 
Tony


#5 Gerard H.

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Posted 05 June 2018 - 01:14 PM

Dear Monika,

 

And once you have the temperature curves of that worst case conditions (with the help of the input above), you can use microbiological predictive outgrowth models. Than you will have a nice simulation of the cooling chain breakage, together with a shelf life study.

 

Kind regards,

 

Gerard Heerkens



#6 Scampi

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Posted 05 June 2018 - 08:17 PM

just some food for thought----determining shelf life including how it's held at home may be a challenge. It would appear there is a big differance between what the home fridge SHOULD be at and what it IS at

 

 

http://theconversati...food-safe-70262

In our study of listeriosis risk factors, we found that although 79% of respondents knew the importance of refrigeration, 84% were unaware that fridges should be 5℃ or less. Furthermore, 65% said they “never check” the temperature of their refrigerator. Later research led us to find that 50-85% of domestic refrigerators were actually operating at higher temperatures than the recommended guidelines, when taking single temperature readings.

We have also looked at how temperature fluctuates in fridges using wireless sensors to track changes on a minute by minute basis over six consecutive days. Surprisingly, we found that no refrigerator was under the recommended 5℃ for the full six days. Around 91% of the fridges had mean temperatures that were higher than the recommended 5℃. Overall, average operating temperatures ranged from -1.7℃ up to 17.9℃. To put that into perspective, the mean temperature for summer 2016 in the UK was 14.9℃.


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#7 Charles.C

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Posted 05 June 2018 - 10:09 PM

just some food for thought----determining shelf life including how it's held at home may be a challenge. It would appear there is a big differance between what the home fridge SHOULD be at and what it IS at

 

 

http://theconversati...food-safe-70262

In our study of listeriosis risk factors, we found that although 79% of respondents knew the importance of refrigeration, 84% were unaware that fridges should be 5℃ or less. Furthermore, 65% said they “never check” the temperature of their refrigerator. Later research led us to find that 50-85% of domestic refrigerators were actually operating at higher temperatures than the recommended guidelines, when taking single temperature readings.

We have also looked at how temperature fluctuates in fridges using wireless sensors to track changes on a minute by minute basis over six consecutive days. Surprisingly, we found that no refrigerator was under the recommended 5℃ for the full six days. Around 91% of the fridges had mean temperatures that were higher than the recommended 5℃. Overall, average operating temperatures ranged from -1.7℃ up to 17.9℃. To put that into perspective, the mean temperature for summer 2016 in the UK was 14.9℃.

 

Hi Scampi,

 

IIRC, despite a recommended <= 5degC,  the legal max. temperature for Fridges in UK is 8degC for the chilled compartment. Studies exist on the "degree" of compliance to such. Curiously there seems no mention of this tolerance in above 2015 UK Link.

 

@ Tony

 

I noticed yr fascinating 2006 UK link is "archived". Is it actually current ?

The content is beautifully, repetitively, convoluted IMO. Presumably a fallout from its being a legal entity. Plus, i anticipate, due the inclusion of several intriguingly referenced exceptions. Such as pertaining to the notorious Co-op ambient hotdogs I suspect.

 

@ Monika

 

As Tony implied, the methodologies for bestowing labelled shelf lives are subjective and often obscure although scientific analyses/publications  do exist (there are many related threads on this Forum). Offhand I think all the publications on shelf life estimation i have seen assume power is maintained. Period.

I think yr query is generally handled in isolation, eg when to reject chilled food after a power failure ?

Officially, I daresay it's highly likely to relate to where you are.

In addition to above info another SOP discussed here several times for chilled failures etc is the 2hour/4hour rule as detailed in various Australian FS publications. You can Google.

IIRC USA/FDA have analogous "dumping" guides to Australia for power failure situations.


Kind Regards,

 

Charles.C


#8 Tony-C

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Posted 10 June 2018 - 11:46 AM

Issues with high domestic refrigerator temperatures were identified in the UK well over 20 years ago. Perhaps what people are not aware of is this issue may extend to retailers/stores.

 

If you are able to identify a particular store or retailer where you seem to get more off complaints for the same products then it is worth investigating. Based on complaint analysis I found a retail store with a broken refrigerator holding our products at 20 degrees C.

 

Kind regards,

 

Tony



#9 Scampi

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Posted 11 June 2018 - 05:02 PM

ewe Tony, that's gross

 

I don't like the open bunker style fridges that are widely used for meats in grocers........the surface temperature depends on the product underneath it being cold enough to hold the top package. Some super large stores at least have flat deep bunkers where product is kept well below the fill line to ensure the temperature is maintained  (in Canada anyway)

 

My local small town grocery store just installed new dairy department coolers with doors, I'm sure it has made a drastic improvement in shelf life at the store......except they have to be filled from the front......so an employee has to prop the door open in order to fill the cooler..........all the cold air comes rushing out

 

My issue in (where I live) is that the grocery store inspection falls under the local health department......yes the understand temperature abuse and proper handling, but I question the ability of this department to understand food safety  (like the butchering department inside them.....awfully close to washroom.....washroom opens directly into area where produce is chopped for making salad etc.) So all of us work very hard to make sure our product is safe when it leaves our establishment, only to have it undone by some teenager at the grocer down the street


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