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Cooling processes for large joints

validation of spore formers

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#1 Foosa

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Posted 13 November 2017 - 12:15 PM

Hi there,

 

relating to my previous query about validation of cooling for meat and meat products I wondered whether anybody could help:

 

I figured out that the cooling of our uncured joints of meat (roast pork and beef) isn't fast enough, especially in the zone between 48 degree celsius and 12.7 degree celsius. Straight after cooking any meassures (e.g. ice dipping) that I apply only gain time in the temperature zone above 48 degree. Especially our roast pork joints are fairly large. Halving them after cooking isn't really an option as it would dry out the cutting sides and create far more waste.

 

I've trialled the products in our blast freezer (as we don't have a proper blast chiller) and first trials had been partially successful (I was a bit cautious whether there could be any detrimental effects to the quality of the roasts - although I wouldn't have thought so, but just to be safe...). I put the products in after an initial 90 minutes 'chill' in the ambient and left them in for a good 2.5 hours. However at the point I took them out the joints were still above 30 degree celcius in the centre, but especially close to the outside and at the bottom were they sat on the metal tray just above zero degree (~3).

 

Any ideas or process examples would be much appreciated!!!

 

Many thanks in advance!


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#2 Charles.C

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Posted 13 November 2017 - 07:54 PM

 

Hi there,

 

relating to my previous query about validation of cooling for meat and meat products I wondered whether anybody could help:

 

I figured out that the cooling of our uncured joints of meat (roast pork and beef) isn't fast enough, especially in the zone between 48 degree celsius and 12.7 degree celsius. Straight after cooking any meassures (e.g. ice dipping) that I apply only gain time in the temperature zone above 48 degree. Especially our roast pork joints are fairly large. Halving them after cooking isn't really an option as it would dry out the cutting sides and create far more waste.

 

I've trialled the products in our blast freezer (as we don't have a proper blast chiller) and first trials had been partially successful (I was a bit cautious whether there could be any detrimental effects to the quality of the roasts - although I wouldn't have thought so, but just to be safe...). I put the products in after an initial 90 minutes 'chill' in the ambient and left them in for a good 2.5 hours. However at the point I took them out the joints were still above 30 degree celcius in the centre, but especially close to the outside and at the bottom were they sat on the metal tray just above zero degree (~3).

 

Any ideas or process examples would be much appreciated!!!

 

Many thanks in advance!

 

 

Hi Foosa,

 

JF(reader)I, previous thread is here -

 

http://www.ifsqn.com...gard-to-spores/

 

I am a little unsure what specific cooling time / temperatures you are currently trying to achieve ?

 

The product's internal temp. profile while cooling relates to "how" it is being cooled but the center of a symmetrical shape will logically lag the outside until equilibrium is established.

 

Crudely, the T vs t curve (ignoring for simplicity the appropriate location to define T/t) will depend on a variety of factors, some of which are notably thickness of product, geometry of product, product (over)loading, system cooling capacity (inter-related to geometry of freezer-chiller, compressor capacity, room insulation, reference target, air velocity, etc).

 

The common operational reason for deficiencies in cooling rates is that the system cooling capacity is simply inadequate for the task. Often due to some/all of the factors mentioned above. This was the point of several of the documents referenced in thread linked above.

 

The previous thread also referenced suggestions as to how, for a given cooling capacity, the cooling rate cud be optimised. If such is done and T/t results remain unsatisfactory the answer is likely to be as per previous paragraph, ie too little cooling capacity.

 

Just to illustrate the degree of discussions this topic has previously generated, here are some previous related threads  (prob. in semi-chronological order). These also include references/attachments to various standards/procedures in use for joints of meat -

 

http://www.ifsqn.com...-after-cooking/

 

http://www.ifsqn.com...g-requirements/

 

http://www.ifsqn.com...ment-procedure/

 

http://www.ifsqn.com...ion-monitoring/

 

http://www.ifsqn.com...a-4lb-meatloaf/

 

http://www.ifsqn.com...ion-guidelines/


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Kind Regards,

 

Charles.C


#3 Foosa

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Posted 14 November 2017 - 02:14 PM

Many thanks for this information, Charles.

 

I'll go through the threads and see what I'll find. 

 

I'm currently working towards the FSIS guidelines and try to fit the products into the various optional scenarios for cooling (cured/uncured, etc.) depending on the T/t curve that has been achieved. Additionally I run the results through Combase (though I've got to assume worst case scenario's for the pH as we can't meassure these ourselves).

 

I'm only very surprised that our joints (though large) when put into an empty blast freezer (operating at -20degree celsius), that can theoretically hold 2 racks of products, but at the time of the trial only hold 1 rack with 2 trays of product on (4 joints), still don't comply with these standards (yet)... I wouldn't have imagined a capacity issue as such as I can't imagine an even more rapid cooling process...

 

Many thanks, I'll have a look at these threads now!

 


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#4 FurFarmandFork

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Posted 14 November 2017 - 05:17 PM

Foosa, given that you're working with beef/pork parts/primals I'm not sure if the normal cooling guidelines apply for the reasons you stated above, simply because getting the internal temperature down in a piece of meat that large takes a huge amount of time.

 

A bit out of my area here, but there's a good article here discussing the laws regarding whole carcass chilling, which seems to focus more on the idea that the carcasses are actually being chilled, and that the surface temperature reaches a safe refrigeration point as soon as possible, since that would be the portion of the meat expected to be contaminated. 

 

Also want to make sure you have the most current guidelines for FSIS... per the 2017 version of appendix B:

 

Option 2 (≤ 1.0 log10): Chilling should begin within 90 minutes after the cooking cycle is completed. All product should be chilled from 120°F to 80°F (48.8-26.6C),  in 1 hour and from 80°F to 55°F (48.8-12.7C) in 5 hours (6 hours total cooling time) followed by continuous chilling until the product reaches 40°F (4.4c). This option applies to: • Fully cooked products (including intact or non-intact meat or poultry). • Products may be cured or uncured although there is a larger safety margin if cured.

 

 

You mentioned that you only gave your cuts 2.5 hours in refrigeration, but you actually have 6 hours of available time, does that help you get there? Your 6 hour time limit doesn't technically start until you reach 120 (48c), so I think you have more time for the meat to cool than you're giving yourself.

 

Finally, you can always submit queries about your supporting data and cooling method to askFSIS, which is an incredibly helpful service FSIS provides to help manufacturers answer questions about what is and isn't okay. They typically answer within a week.


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#5 Charles.C

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Posted 15 November 2017 - 06:53 AM

Many thanks for this information, Charles.

 

I'll go through the threads and see what I'll find. 

 

I'm currently working towards the FSIS guidelines and try to fit the products into the various optional scenarios for cooling (cured/uncured, etc.) depending on the T/t curve that has been achieved. Additionally I run the results through Combase (though I've got to assume worst case scenario's for the pH as we can't meassure these ourselves).

 

I'm only very surprised that our joints (though large) when put into an empty blast freezer (operating at -20degree celsius), that can theoretically hold 2 racks of products, but at the time of the trial only hold 1 rack with 2 trays of product on (4 joints), still don't comply with these standards (yet)... I wouldn't have imagined a capacity issue as such as I can't imagine an even more rapid cooling process...

 

Many thanks, I'll have a look at these threads now!

 

Hi Foosa,

 

Assuming low-loaded, the rate likely particularly depends on the cooler/fan power(air velocity) and size/shape/weight/moisture content of joint.

 

The "cold"/fan power should "hit" you in the face when you enter. :smile: .

 

The "driving" temperature IMEX of 1-5 ton coil-fan blast freezers is typically -30degC or lower.


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Kind Regards,

 

Charles.C


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#6 Foosa

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Posted 15 November 2017 - 10:27 AM

FurFurmandFork: yes, I'm working towards the most recent version of FSIS. Although you are referring to product surface temperature I very much believe those guidelines refer to internal/core temperatures? I personally would completely agree with you that product surface is the most critical 'area' if you're roasting an intact piece of meat (roast pork/roast beef) - that were I would suspect higher amounts of pathogenic bacteria (rather then in the centre of a joint).

 

I know, I was a bit cautious with the blast freezing as I wasn't entirely sure whether we could expect negative quality impacts (one of the operatives mentioned the colour of the meat could change). I obviously only considered the time frame when reaching 48 degree celsius. However, the initial drop of temperature after cooking is far greater and is obviously slowing down the 'colder' the meat gets. So if you put a roast joing in the freezer after say 90 minutes of cooking you experience a fairly good drop of temperature fairly quickly- but in the temperature range that's not so much of interest (>48). I think I'll aim for getting down to at least 26degree celsius  (core temperature) in the freezer before I transfer the product to the chiller.

 

Charles: our maintenance team looked at the freezer and as much as I know it's currently working as good as it can... Most of our machinery/equipment is already a little bit old...

 

The thing is, I'm in the UK and we don't have any guidelines from our Food Safety Authohrity (or the ones that we have are even more strict and less achievable from my point of view). I'm asked to validate our CCP cooling and back this up with scientific papers and/or combase modelling - and at least I'm not far off from a 'modelling' point of view... 


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#7 Derf

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Posted 23 November 2017 - 04:37 AM

Hi - You mention having difficulty from 48 to 12.7 but don't mention actual times or times you are trying to achieve. That would be useful. The other piece of useful information would be what packaging the product was in, permeable or impermeable casing.

 

It is difficult to decrease the temperature of large cuts of meat at a rapid rate without being detrimental to quality. Any freezing will have a negative impact, as will very high velocity fans, particularly on permeable casing.. What works best is systems that use surface and internal temperature probes and adjust ambient conditions accordingly. High velocity, -10C at start, slowing and ramping up to 0-2 at end of cycle.

 

A method to assist the chillers would be to spray the product with water after cooking to remove some of the heat. This will (likely) be way easier to achieve and is more controllable and better for quality than ice dipping. Even ambient temperature water (fine mist) will help. (10-15 minutes typical) Don't particularly like the idea of the 90 minutes in ambient....

 

You also mention "on the metal tray".  May have this wrong but if it is a solid tray, suggest replacing with wire tray so there is better air flow around the base of the pork.

 

 

As mentioned in my last note 52-12 in 6 hours "works". As a country we do not have heaps dropping over from rampant spore formers.   (hmmm maybe a risky test method but hey...) 

And if you are anal about spores ......  https://en.wikipedia.../Tyndallization


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#8 Foosa

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Posted 23 November 2017 - 09:00 AM

Derf,

thanks for your valuable feedback! 

here in the UK we don't have any precise guidance about how quickly the joints are supposed to cool. I'm asked to validate our CCP chilling with regard to spore formers, backing it up with either scientific papers or microbiological modelling. 

Hence why I was looking out for guidance and then came across the FSIS guidance. I therefore either have the choice to achieve:

54ºC - 26ºC: < 1.5 hours and

26ºC - 4ºC: < 5 hrs

or 48ºC – 12.7ºC: < 6 hours and chilling to continue from 12.7ºC – 4.4ºC. 

I had achieved about 7 hours (~3 hrs from 48-26 and 4 hrs from 26 -12.7. 2.5 hours of the first 3 hrs the product spent in a blast freezer. Rest of the chilling was carried out in a normal holding fridge (we don't have a blast chiller)).

I had run this through combase and got just over a 1 log10 predicted increase of growth.

 

In all this discussion about spore formers I still don't understand why the core-temperature of a joint is so relevant as I would assume spores most likely to sit on the surface of the meat??? I can appreciate this to be of importance for a minced meat product or similar - unfortunately I'm not a microbiologist!


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