Bacon curing - validating the 10% uptake assumption

Discussion in 'Food Safety' started by wade, Jan 28, 2015.

  1. wade

    wade Master of the Pit OTBS Member SMF Premier Member

    Following a couple of recent threads where the uptake properties of Nitrite by bacon was debated at great length (with a little more vigor at times than I was expecting), it became clear that there were certain assumptions that were being used to calculate the uptake of Nitrite in bacon when immersion curing that had little credible supporting evidence. Whilst there is no reason to doubt the validity of these assumptions there also appears to be little laboratory based evidence to support them either. The assumption that appears to have the least supporting evidence so far, and I hope to validate, is that when the pork is immersed in the concentrated curing brine, 10% of the cure concentration in the brine will be taken up by the meat. 

    There was also a big difference in the methodologies of some of the recognised authorities on curing here on the forum - with two of them recommending very different starting concentrations of cure. To try to verify both of these methodologies I am going to compare both methods, as published on here, using laboratory techniques and at the end of the process have all of the samples analysed for residual Nitrite at a government licensed food safety laboratory. I am fully expecting both methods to result in a "safe" end product (one that falls within the governments maximum and minimum limits for Nitrite), however I am expecting them to probably be at either ends of these limits. 

    So that I can maximise the value of the testing I have outlined the methodology that I intend to use below. This will give other forum members the opportunity to comment on the process before it begins. No testing will be absolutely perfect and test all possible variables but I am looking to test the major assumptions first - and these may be refined further in future testing.

    As the commonly used cuts of pork used for bacon on here are Belly and Loin I intend to test both cuts. To try and reduce animal variation, if possible, I will try to use cuts of meat from the same pig for all of the testing. I will be looking for a sample size of 1Kg (2.2 Lbs) each as, although not big, is a size that may well be commonly cured by our members. These tests will all be performed skin off.

    The two brines I intend to use are:

    1 US gallon = 3.78 litres

    1 Cup of sugar = 240 g

    1 Cup of salt = 273 g

    1 Tbs Cure#1 = 17 g

    Cure#1 = 6.25% Nitrite and 93.75% Salt
    Brine # 1 - Thread brine from "Prague Powder #1"
     Per 3.5 US GallonPer 5 Litres
    Cure #114 oz (397 g)150.04 g
    Brown Sugar2-5/8 cups (630 g)238.1 g
    Salt3/4 Cup (204 g)77.1 g

    This has a starting Nitrite concentration of 9.38 g per 5 litres = 1,875 mg per litre
    Brine # 2 - Pops Lo-Salt Brine
     Per US GallonPer 5 litres
    Cure #11 Tbs (17 g)22.49 g
    Brown Sugar1/2 Cup (120 g)158.7 g
    White Sugar1/2 Cup (120 g)158.7 g
    Salt1/2 Cup (136.5 g)180.6 g 

    This has a starting Nitrite concentration of 1.41 g per 5 litres = 281 mg per litre

    In the various threads on the forum there is also variation in the recommended time that the meat remains in the brine, so I will test each of he cuts of meat in each brines for both 7 and 14 days. Including the control samples this will result in 12 samples being tested:

    Sample 1    Uncured sample from Belly Pork to act as a control
    Sample 2    Uncured sample from Pork loin to act as a control
        
    Sample 3    Belly pork from Brine #1 after 7 days
    Sample 4    Pork loin from Brine #1 after 7 days
        
    Sample 5    Belly pork from Brine #1 after 14 days
    Sample 6    Pork loin from Brine #1 after 14 days
        
    Sample 7    Belly pork from Brine #2 after 7 days
    Sample 8    Pork loin from Brine #2 after 7 days
        
    Sample 9    Belly pork from Brine #2 after 14 days
    Sample 10   Pork loin from Brine #2 after 14 days
        
    Sample 11   Sample of Brine #1 before pork added
    Sample 12   Sample of Brine #2 before pork added

    I may also test a sample of meat that has been previously frozen to see if that has any effect on cure uptake.

    At the beginning, a control sample of each cut of pork will be taken to measure initial Nitrite levels (if any). These will be vac packed and frozen.

    Each sample of meat will be weighed before being placed separately in individual containers of brine.

    After the allotted time in the brines the samples will be removed, patted dry and weighed.

    The sample will then be left in the fridge for 24 hours to equilibrate, patted dry and weighed again before a central cross section sample is cut.

    Each sample will then be vac packed and frozen.

    At the end of the trial the frozen samples will be delivered by hand to the government licensed laboratory for testing.

    The sample preparation and storage methodology above has been pre-approved by the laboratory.

    The lab turn around for the testing is 10 working days (2 weeks) and as soon as I receive the results I will publish them in full.

    If you have and suggestions or comments on the methodology then please let me know over the next few days before I begin the trial.

    This should be fun to do and will hopefully provide the lacking evidence to support, or otherwise, the methods that are being routinely recommended on the forum.

    Cheers

    Wade

    Post updated to reflect the increased salt from Pops brine as requested.

    Post updated to use Pops Lo-Salt curing brine as requested
     
    Last edited: Jan 29, 2015
  2. c farmer

    c farmer Smoking Guru Staff Member Moderator OTBS Member SMF Premier Member

    [​IMG]
     
  3. atomicsmoke

    atomicsmoke Master of the Pit OTBS Member

    That's a sound DOE (design of experiment) Wade.

    The only suggestions I have:

    - use of weight/weight concentration (instead of wt/vol) and add the weight of the other ingredients to the brine total mass.
    - for brine#2 the weight of the meat is used in the handbook quoted everywhere to estimate the nitrite level in meat:
    Curex0.0625/(meat+brine)

    Good luck and thank you for your time and $.
     
  4. wade

    wade Master of the Pit OTBS Member SMF Premier Member

    I love science. This is a labour of love. Sad I know, but I don't apologise [​IMG]

    Using Mg/Litre is where I am trying not to be controversial. Some on here say that you have to take into account the weight of all of the ingredients whereas others say only the weight of the Nitrite. So as to try to remain impartial I have just shown the brine concentrations in mg/Litre of Nitrite. The only thing that this will change depending on your viewpoint is the calculated initial Ppm. As in this experiment I am not going to calculate anything, I am just using the ingredients that others have recommended and am using the methodologies that have been described. In the end I will simply measure what is in the final bacon. That way we can apply whatever calculations we want and see which one most closely models what actually happens.
     
  5. wade

    wade Master of the Pit OTBS Member SMF Premier Member

     That is great but I don't recall it being mentioned during the previous threads when requested. Do you have a summary of the conclusions? If not I will have to buy it.

    Cheers

    Wade
     
  6. It wasn't requested in the previous discussions.
    It has nothing directly to do with the science regulators used to determine nitrite/nitrate limits and define curing practices.
    I have the paper somewhere, I'm just not sure where...it's likely in storage.
     
  7. atomicsmoke

    atomicsmoke Master of the Pit OTBS Member

    Fair enough.
     
  8. pops6927

    pops6927 Smoking Guru Staff Member Moderator Group Lead OTBS Member SMF Premier Member

  9. chef jimmyj

    chef jimmyj Smoking Guru Staff Member Moderator Group Lead OTBS Member

    This should be interesting. Thank You for going through the work and expense to contribute to keeping or members safe when it comes to Curing Meat...JJ
     
  10. wade

    wade Master of the Pit OTBS Member SMF Premier Member

    Hi Pops. What I was using was from your post http://www.smokingmeatforums.com/t/110799/pops6927s-wet-curing-brine

       For every 1 gallon of water, add:
       1/3 - 1 cup sea salt (depending if you're on a lo-salt diet)
       1 cup granulated sugar or Splenda®
       1 cup brown sugar or Splenda® brown sugar mix
       1 tbsp cure no. 1 pink salt


    I have now updated the salt quantity above to reflect your other post as requested.

       1 gallon of clean water
       1 cup plain, regular non-iodized table salt
       1 cup sugar or sucrolose
       1 cup brown sugar or sucrolose equiv.
       1 tablespoon of Cure#1
     
  11. bear55

    bear55 Master of the Pit

    This is interesting.  Will you assume that every piece of meat cured in the future will follow the results of this test?  I wonder if that will be a valid assumption?
     
  12. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Wade, morning.....   I don't know if this is pertinent..   from the FSIS handbook 1995, page 28.....

    From the wording,  "Since the skin retains practically no cure solution or cure agent" ..  one would have to assume, (stupid, I know), some testing had to be done, to make that statement...

     Pumped, Massaged, Immersion Cured, or Dry Cured Bacon (rind-on):  The maximum limit for ingoing nitrite and sodium ascorbate or sodium erythorbate must be adjusted if bacon is prepared from pork bellies with attached skin (rind-on).  A pork belly's weight is comprised of approximately 10 percent skin.  Since the skin retains practically no cure solution or cure agent, the maximum ingoing nitrite and sodium ascorbate or erythorbate limits must be reduced by 10 percent.  For example, the maximum ingoing limit for nitrite and sodium ascorbate or erythorbate for pumped pork bellies with attached skin would be 108 ppm [120 ppm ! 12 ppm (120 × .10)] and 495 ppm [550 ppm ! 55 ppm (550 × .10)], respectively.
     
  13. pops6927

    pops6927 Smoking Guru Staff Member Moderator Group Lead OTBS Member SMF Premier Member

    I would prefer you use the lo-salt formula or better yet, both, as it is part of YAWYE (You Are What You Eat).  The post of Pop wet curing brine is on 08/30/11.  On 09/07/11 I had a massive 3rd of 5 strokes, almost killing me.  The second was in Oct. 2014, but reflecting the change from my 5 strokes and still keeping in YAWYE form.  Thank you.
     
  14. wade

    wade Master of the Pit OTBS Member SMF Premier Member

    Hi Dave. Yes I think this is very relevant, however to keep the initial number of samples manageable I was planning on all off these samples being skin off. Initial plans for a phase 2 (getting ahead of myself already!) would be to take one of the cure environments and then test the effect of skin on and off.

    The other test I think need doing is the effect of brine quantity in relationship to the volume of the meat being cured. The size and shape of the curing container will significantly effect the volume of brine needed to cover it. Would there be any difference in uptake if the brine quantity was equal to the meat volume, twice the meat volume, 10x the meat volume etc. ?
     
  15. wade

    wade Master of the Pit OTBS Member SMF Premier Member

    Hi Pops - If you would prefer that I use the lo-salt formula then I will do that. I try to keep things as low salt as possible these days for health reasons too.

    In line with what I replied to Dave, maybe in the next phase I could test the higher salt brine and we could compare the difference.
     
  16. wade

    wade Master of the Pit OTBS Member SMF Premier Member

    Yes there is an assumption there, however incorrect assumptions can potentially lead to costly mistakes. I have had a look at the handbook and they do not seem to offer any reference source for this statement. As it is in an official government publication I don't assume for one moment that this isn't totally accurate - but it is one that is kind of made off-hand and it would have been great to have a source reference too. I am certain that there has been LOTS of research done in this area over the years - the problem is really finding it anf identifying the actual facts from the colllective assumptions. This does not affect the question of the 10% cure uptake by the meat though.
     
    Last edited: Jan 29, 2015
  17. wade

    wade Master of the Pit OTBS Member SMF Premier Member

     
    Last edited: Jan 29, 2015
  18. inkjunkie

    inkjunkie Master of the Pit

  19. pops6927

    pops6927 Smoking Guru Staff Member Moderator Group Lead OTBS Member SMF Premier Member

    I still do not understand the intent of your experiment.  Are you looking at the uptake in weight from soaking in the brine, or from injecting 10% pump into the meat?
     
    Last edited: Jan 29, 2015

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