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

    The final batches are now out after 14 days in the brine


    All of the brines are looking decidedly murky with a distinct sediment on the bottom of each container. The smell was slightly meaty but was not unpleasant


    There were distinct threads in the brine and as the brine was poured away there was a thick slime that has sunk to the bottom of the containers. This was also on the surface of the meat but it washed off easily.

    The joints were washed and then patted dry before weighing. They were then labelled and put on wire racks ready to equalise in the fridge. I will let them rest for 5 days before slicing and sampling.


    Samples of each of the belly brines were also taken to be analysed - these were vac packed and frozen.

    After 14 days there was a marked difference in weight increase between the loin and the belly. The loins were fairly similar at ~10% increase however the bellies increased in weight between 16%-20%
    BrineMeatDaysBrine
    Volume
    In
    Date
    In
    Weight g
    Out
    Date
    Out
    Weight g
    %
    Increase
    1Loin145 Litres02/02/2015109616/02/201512051.10
    1Belly145 Litres02/02/201599716/02/201511941.20
    2Loin145 Litres02/02/201593016/02/201510171.09
    2Belly145 Litres02/02/2015102616/02/201511931.16

    The trial is not complete but there are several things we can infer from the results so far:
    • There is a distinct difference between the two cuts of meat as to how much liquid that can be absorbed over a 14 day period. The pork belly was capable of absorbing twice the volume of brine than the loin
    • The assumption that the pork will only take up 10% of its weight of the brine needs to be reviewed and the different cuts of meat need to be taken into consideration. In this experiment the belly was shown to take up up to 20%.
    • With the more concentrated brine in pork belly, even discounting the diffusion of brine into the cellular fluids of the meat itself, it is possible/probable that the resulting nitrite in the belly pork will be at least 2 x that which was originally calculated. We cannot tell for sure though until we get the lab results.
    Next update in 5 days [​IMG]  
     
    Last edited: Feb 16, 2015
  2. Where is this assumption coming from?
     
  3. wade

    wade Master of the Pit OTBS Member SMF Premier Member

    And then there was skin. Here are the results for the skin after 14 days in the brine:
    BrineMeatDaysBrine
    Volume
    In
    Date
    In
    Weight g
    Out
    Date
    Out
    Weight g
    %
    Increase
    1Skin141 Litre02/02/201511416/02/20151711.50
    2Skin141 Litre02/02/201512216/02/20151941.59

    A 50%-59% increase. Now that was unexpected ! This gives a potential of between 5x and 6x the calculated cure concentration in the skin area of the meat if it is left on.

     
    Last edited: Feb 16, 2015
  4. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member



    It may absorb water.... does it absorb salt and nitrite in representative amounts...
     
  5. atomicsmoke

    atomicsmoke Master of the Pit OTBS Member

    Given enough time the "liquid" in the meat will have the same concentration of salt/nitrite as the brine around the meat. Is 14 days long enough for equalization? We'll see when Wade gets the sample tested.
     
  6. wade

    wade Master of the Pit OTBS Member SMF Premier Member

    From the posts in the original Prague Powder threads where it was claimed that with this immersion brine method there was an assumed 10% cure pickup. When Atomicsmoke asked about how this was arrived at he was told that "Just so there's no confusion and everyone understands....percent pick-up is the total amount of brine solution absorbed by the cured product in relation weight."

    For this to be true then for the 10% assumed pickup rate in the calculation would require there to be a brine uptake of around 10% by weight. For the loin this was true but for the belly it was twice this amount.
     
  7. wade

    wade Master of the Pit OTBS Member SMF Premier Member

    That we don't know yet. It is likely that the absorption will be non specific diffusion though - but we will have to wait and see
     
  8. This is a persistant misunderstanding.
    I've pointed out several times that there is no assumed 10% pick-up.
    10% pick-up was used in the calculation (and often is) to determine compliance with the nitrite limits (AT 10% pick-up ONLY) as set by the FDA and USDA, it's only a test.
    According to the USDA's equations or methods, a cured product either complies or does not comply at any given pick-up percentage....if it does not comply....adjustments need to be made.
    I don't know how else to say it, it's pretty simple really.
     
  9. I'm curious why you didn't go with a skin-on belly.
    That would be much more in context.
     
    Last edited: Feb 16, 2015
  10. wade

    wade Master of the Pit OTBS Member SMF Premier Member

    Not really. I always cure mine skin off and there is an assumed calculation to make adjustments for leaving the skin on. This test was with skin off - maybe the next one could be with skin on to see if the adjustment holds true in practice. The skin test was really an afterthought to see just how much skin by itself would absorb compared to the meat.

    Part of different post edited out
     
    Last edited: Feb 16, 2015
  11. Part of the what?

    Yes, I know, that's what I meant by staying in context.
     
  12. wade

    wade Master of the Pit OTBS Member SMF Premier Member

    Unfortunately the 10% assumption is built into the calculations you posted for this curing method and so I cannot see how you can say that the 10% pickup is not assumed

    If the 10% isn't 10% then what is it?  If it turns out to be 20% - as appears to be the case of the belly pork - then the calculated Nitrite in your post would be closer to 344 Ppm than the 172 Ppm in the calculation. This would be a big difference. 
     
  13. wade

    wade Master of the Pit OTBS Member SMF Premier Member

    Martin - if it makes you feel happier just forget the added test of the skin. It is for my own information and has no particular bearing on the other testing being undertaken.
     
  14. It would be in compliance (according to the 'rulers') in the example above at 10% pick-up OR 10% pump.
    If one pumps the meat or immerses to meat to 20% pick-up or pump it's not in compliance.
    So, common sense dictates not pumping OR immersing beyond 10% pump or pick-up to stay in compliance.
     
    Last edited: Feb 16, 2015
  15. wade

    wade Master of the Pit OTBS Member SMF Premier Member

    I have seen this documented with regards to pumping but not to brining. We will see what happens when the results come back.

    Next update in 5 days when the final joints are sliced.
     
  16. I seriously doubt they'll be the same.
    It's all approximations (or acceptable ranges) anyway.
     
    Last edited: Feb 16, 2015
  17. I looked through some of my USB thumb drives (about 150 GB of meat curing & sausage making and curing info so far) and while it's not the info I was looking for I did find a few good pieces...

    Here are a couple.....

    Diffusion coefficients for the Chloride Ion, NO3 and NO2 in some pork and beef muscles....it illustrates why actual pick-up may be all over the place.....

    Diffusion of Salt in Food and Diffusion of Sodium Chloride in Pork Tissue....
    [ATTACHMENT=1940]pub_ReggM_1985_135041.pdf (1,443k. pdf file)[/ATTACHMENT]
    [ATTACHMENT=1939]11016527.pdf (326k. pdf file)[/ATTACHMENT]
    Plenty of references cited in both.
     
    Last edited: Feb 16, 2015
  18. atomicsmoke

    atomicsmoke Master of the Pit OTBS Member

    The 10% pickup "factor" is referenced all over the web. After-immersion weigh-in is rarely mentioned. One is likely to assume the belly will pick up 10% regardless of time spent in brine. Even in the "Prague powder " thread the after-immersion weight was not mentioned until after Wade and I question the "10% pickup" ppm levels.
     

  19. All it really takes to understand this is a close look at the "rulers'" equation I posted and the understanding that "at" really does mean "at."

    "Weight of the Nitrite x Percentage of Brine Pick-Up x 1,000,000 ÷ Total Weight of the Brine = PPM Nitrite"

    There's no mention of 10% pick-up or time in the equation ...

    ....but further down.

    At 10% pick-up, it's within the 200PPM government limit used by many folks as a measure of safety.
     
    Last edited: Feb 16, 2015
  20. atomicsmoke

    atomicsmoke Master of the Pit OTBS Member

    Yet...not mentioning of "this method requires close monitoring to ensure you don't exceed 10% pickup". That 10% is considered a given. Look it up in other meat curing forums (sausagemaker).
     

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