Literature Validation of thermal treatment
Some remarks in the recent HACCP audit we went through have made me realize I should stop reading and start asking questions in the forum. I am in charge if several production lines of dried soy proteins (powders and extruded pieces), but my question for now is more general.
The standart CCL we use for our thermal treatment CCP are the standard "72 centigrade 15 seconds" limits for pathogens inactivation. However the auditor noticed there was not validation for this standard.
Are there standard validations for microbial treatment, preferably with various temperature-time connections? Something organized that I can show the HACCP team, approve, file in the HACCP scheme and continue to use the 72-15 rule that all our operators know by heart?
The main bacterial dangers we control are Salmonella, E. Coli, Clostridium Preferengis and Staph. Aureus.
Thanks for your help
Itay
There is a very useful table in the CFA "best practice guidelines for the production of chilled foods" on p12. If you don't have a copy, the reference they took the information from was Food Microbiology 1989 6 p251-259 and also technical memorandum No. 523 from the CCFRA (although the chilled food best practice document is a useful one so it might be easier to buy it.)
Your value of 72 degrees 15 seconds is, IMO wrong. Could it have been a typo at some point in the history of your HACCP plan? According to the figures in this table (and I've seen these repeated regularly in other HACCP plans), 72 degrees should be held for 1 minute and 5 seconds to achieve a 6 log reduction in vegetative Listeria. If you can only hold for 15, you should heat to 77 degrees.
IMO all of that literature stuff should always be backed up by some practical testing as part of that validation. If you go for lower temperature / time combos though I would suggest you need full validation of that temperature and time in your product type.
In this table, they state, and I agree that you could use these figures to control other vegetative pathogens; however, this does not control spore forming pathogens and will not control heat stable toxins.
I think you should consider whether Clostridium perfringens is a genuine risk in your product as it won't currently be controlled and to be honest I'd doubt it would be an issue. I would also consider whether S. aureus could be controlled through GMP routes as any toxin formation before this heat process would not be distroyed, I would also consider that B. cereus is a hazard and it's not a bacterium you will ever kill with your process but you should ensure your cooling time is sufficiently short to prevent toxin production during that time or water activity is sufficiently low in the product to prevent any issues.
An interesting question itay.sh and lots of people just accept these figures. You might be interested to see where they come from, I certainly was when I looked into it approx 4 years ago when we had the same issue arise.
There is a very useful table in the CFA "best practice guidelines for the production of chilled foods" on p12. If you don't have a copy, the reference they took the information from was Food Microbiology 1989 6 p251-259 and also technical memorandum No. 523 from the CCFRA (although the chilled food best practice document is a useful one so it might be easier to buy it.)
Your value of 72 degrees 15 seconds is, IMO wrong. Could it have been a typo at some point in the history of your HACCP plan? According to the figures in this table (and I've seen these repeated regularly in other HACCP plans), 72 degrees should be held for 1 minute and 5 seconds to achieve a 6 log reduction in vegetative Listeria. If you can only hold for 15, you should heat to 77 degrees.
IMO all of that literature stuff should always be backed up by some practical testing as part of that validation. If you go for lower temperature / time combos though I would suggest you need full validation of that temperature and time in your product type.
I think you should consider whether Clostridium perfringens is a genuine risk in your product as it won't currently be controlled and to be honest I'd doubt it would be an issue. I would also consider whether S. aureus could be controlled through GMP routes as any toxin formation before this heat process would not be distroyed, I would also consider that B. cereus is a hazard and it's not a bacterium you will ever kill with your process but you should ensure your cooling time is sufficiently short to prevent toxin production during that time or water activity is sufficiently low in the product to prevent any issues.
Thanks for your answer. Our products are dry, and most of our heat treatments are designed for protein denaturation anyway (say, 140 degrees or ethanol soak) and therefor we never questioned the 72-15 rule.
I don't guess there's any public-accessable figures you know of?
Anyone else got any free references on this?
Dear Itay,
The time / (core) temperature combination will depend on things like the specific target bacterium / food matrix / D value / desired bacterial reduction. The procedure which generates the utilised tables of paired values is available in certain Codex documents amongst others (it requires the use of certain averaged experimental data so we are not talking about absolute parameters here) . Tables of values are also published on the net (somewhere). There are several threads here with links to some of these sources (don’t remember which offhand, sorry). As GMO mentioned, various EU countries use L.monocytogenes and nominate 70degC / 2mins minimum or comparable paired values, don’t remember the associated log reduction target offhand but probably 6. I think the reason for the choice of L.monocy…. is that it is often the most difficult to kill, commonly encountered, species for many food matrices.
However, globally, other opinions occur and there are other targets and D values used, eg the USA do not follow the above in the meat industry and in fact you can find different USA guidelines depending on the selected reference. This aspect relates to ongoing arguments over the safety of the popular (in USA anyway) “undercooked” hamburger. Another example is that the UK formally seems to use the 2min/70degC rule but one can still find an older alternative which (from memory again) was simply to achieve a central value of 75degC, the killing power presumably giving a necessary time of approximately zero.
In this context “correct” becomes a relative term unless a regulatory issue is involved. Yr current values may well be “correct” for you if you can find the appropriate bacterium, D value etc data. Maybe an American datum which tend to be generally less demanding than EU I think. No doubt someone here will shortly prove me wrong.
This doesn’t immediately answer yr original post, the only link I can remember offhand is the well –known site (Ch.C/link now broken/deleted) which discusses the thermal cooking requirements from an American perspective. I suggest you do a bit of searching on this site for other links, I know they exist.
Rgds / Charles.C
PS within my link above, can see this page (Ch.C/link now broken/deleted) where the table clearly does not quite match yr case but is perhaps even "easier" to fulfil than yr criteria (if one were talking about an equivalent situation).
Whenever it comes to the microbes problems, I am always lookin' for this:
http://www.nzfsa.gov...ce/data-sheets/
and this:
http://www.foodsafet...~mow/intro.html
My opinion is, no matter how good is your reference, you need to validate your own process. I mean, at least you need to know that your temperature is really able to reach 72oC for 15 seconds, and really able to kill pathogenic microbes. Perhaps thats what demanded from the auditor. As for the rest, I'll leave you to the two experts here...
Regards,
Arya
Yr first link is potentially very interesting but after a quick look the thermal data given is very strange and questionable. The time required seems to be the same for non-typhoid Salmonella and L. monocytogenes species which is, I think, scientifically highly unlikely if referred to the same bacterial reduction value (this is also unfortunately not mentioned). I guess the reason is that the same species is being used as a reference in both cases but which species ??! Maybe there is a clarification somewhere else in the document.
Rgds / Charles.C
@ Itay - added - lethality tables for L.monocytogenes and non - proteolytic, C.botulinum typeB as used by USFDA for seafood in their HACCP guide are given in link below (see pg 283) (other people also use L.mono...data for many other foods I think) -
http://seafoodhaccp....e_pdf/App04.pdf
The first table illustrates the 70degC / 2min rule (although it hardly supports a claim for 75degC as a satisfactory instantaneous value which I hv also seen ?). The data at 72degC obviously does not match your situation if a 6D process involved. your reference bacterium is perhaps a salmonella species or a lower log reduction involved .
It is possible that yr 72degC-15sec guide was taken from one specific reference which may take rather more finding. Having probably ruled out L.mono, need to find a generalised lethality table for salmonella if this exists. Arya's link for salmonella referred above may still be one possible answer but where does the data come from and what does it mean ??
I think some validation work needs to be done to confirm the 72 / 15 secs. Before you start though, it might be worth having a hunt around and asking employees who've been there a long time to make sure it doesn't already exist (somewhere!)
Otherwise for me, you'd have to design an experiment (in a lab not on your site) where the product is deliberately innoculated with the bacteria you want to control and then prove the heat process kills it. If you just do it with site samples it can be annoyingly difficult to find some raw material actually containing the pathogen! (Although that doesn't mean it's impossible. It's rare to get Salmonella in non heat treated flours but it's significant enough to be a risk.)
Or you could just up the temperature. I don't know if that's feasible? Probably easier than extending the time?
This doesn’t immediately answer yr original post, the only link I can remember offhand is the well –known site (link now broken/deleted) which discusses the thermal cooking requirements from an American perspective. I suggest you do a bit of searching on this site for other links, I know they exist.
Rgds / Charles.C
PS within my link above, can see this page (link now broken/deleted) where the table clearly does not quite match yr case but is perhaps even "easier" to fulfil than yr criteria (if one were talking about an equivalent situation).
This is being flagged as an adult video website.
This is being flagged as an adult video website.
Hi wbourg,
Thks for the info.
14 years old thread.
Times can change. +/-.