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[Oddley]

As you know I have been calculating brine cures for myself and other's for a while. I have just come across some information that will make those cures inadvisable to use in the future. I have just posted the address of the PROCESSING INSPECTORS' CALCULATIONS HANDBOOK.

In the handbook it shows two ways of calculating a brine one short term one long term. If you are using one of my brine for short term or pumping then they are fine if you are using them to completely cure to equalisation the don't use them. as they should be calculated differently.

But make up your own mind as the following is the relevant text.

! Method One

The first method assumes that the meat or poultry absorbs not more than the level of nitrite in the cover pickle. Hence, the calculation for nitrite is based on the green weight of the meat or poultry (as is the case with pumped products), but uses percent pick-up as the percent pump. The percent pick-up is the total amount of cover pickle absorbed by the meat or poultry. It is used in the calculation for immersion cured products in the same way percent pump is used in the (previous) calculation for pumped products.

< Calculation Formula (using % pick-up)

lb nitrite � % pick-up � 1,000,000
------------------------------------------- = ppm
--------------lb pickle

! Method Two

The second method assumes that the submerged meat, meat byproduct, or poultry and the cover pickle act as a single system. Over time, the ingredients in the pickle, such as nitrite and salt, migrate into the meat, meat byproduct, and poultry until levels in the tissue and in the pickle are balanced. This system is actually very complex and dynamic, with components in constant motion, but it will reach and maintain a state of equilibrium. Therefore, the calculation for ingoing nitrite is based on the green weight of the meat block, using the percent added as a relevant amount.

< Calculation Formula (using the green weight and pickle weight)

----------lb nitrite � 1,000,000
------------------------------------------------- = ppm
green weight (lb) meat block + lb pickle

In immersion cured products, this formula can be used to determine:

(1) The permitted weight of nitrite, if you know the green weight of the meat block and the weight of the pickle solution.

(2) The minimum weight of the meat block that can be submerged in the cover pickle, if you know the weight of the nitrite and the weight of the pickle solution.

(3) Whether or not a procedure will be in compliance with the regulations, if you know the weight of the nitrite, the green weight of the meat block to be immersed, and theweight of the pickle solution.

Note: Method One is used for hams, shoulders, bellies, etc., because it takes weeks for these
large items to reach equilibrium. Method Two is primarily used with small items with large
surface areas such as pigs' ears, tails, snouts, etc.

[saucisson]

Thanks Oddley, very useful and important information.

Dave

[dougal]

That is absolutely splendid. Thank you for posting that.
I am delighted to add some more specifics to my knowledge.

I note that it says that "larger items than ears" etc would take "weeks" to reach equilibrium - HOWEVER - where immersion curing traditionally, the time of immersion really would be "weeks" - Vernon recently cured his 6.5 kg leg for 4 weeks. Calculations based on equilibrium conditions should be perfectly valid for such curing.
The quoted curing times for such equilibrium curing would be the *minimum* to achieve equilibrium, and {I am presuming} there would therefore be no harm in curing for longer (though there would be no commercial production advantage in doing so.)
My geeky newbie suspicion is that such curing would usually be intended to lead to rather heavily salted (and hence well preserved) ham. My suspicion is that such hams would potentially be held for ages in the brine before being soaked to de-salt and cooked.

I have never seen any calculations relating to de-salting by soaking or re-boiling in fresh water. These treatments to lower the salt content will also be reducing the nitrate/nitrite levels.

I interpret the advice regarding Method 1 to be that for short cures one should estimate the salts taken in as being in direct proportion to the measured weight actually picked up.
EDIT to add an explanation of that last bit: Method 1 is assuming that if the meat after a 'short' immersion cure has gained 200 grams, then it is a fair assumption that it will have picked up "not more than" whatever salt, nirate, nitrite, etc is to be found in 200 g of the starting composition of the curing brine. Expressing the measured weight gain as a proportion (%) allows the amount of brine ingredient (nitrate for example) to be calculated as a proportion of the meat weight.

[dougal]

! Method One

The first method assumes that the meat or poultry absorbs not more than the level of nitrite in the cover pickle. Hence, the calculation for nitrite is based on the green weight of the meat or poultry (as is the case with pumped products), but uses percent pick-up as the percent pump. The percent pick-up is the total amount of cover pickle absorbed by the meat or poultry. It is used in the calculation for immersion cured products in the same way percent pump is used in the (previous) calculation for pumped products.

< Calculation Formula (using % pick-up)

lb nitrite � % pick-up � 1,000,000
------------------------------------------- = ppm
--------------lb pickle

While I agree with the logic, I'm not sure that the arithmetic is being reproduced correctly.

The proportion of (here) nitrite in the pickle is (lb nitrite) � ( total lb of brine or 'pickle')
Since we are calculating the *proportion*, it doesn't matter what the units are - as long as they are consistent, all pounds, all grammes, all whatever as long as its the same.
If we have measured the weight gain and calculate it as a percentage, and make the assumption that the nitrite gain is in proportion to the amount in the brine, then the *percentage* nitrite in the *meat* is going to be
lb nitrite � % pick-up
---------------------------
lb pickle
we need to divide it by 100 to express it as a proportion,
and then multiply by 1,000,000 to express it as parts per million, ppm.

For those reasons, I think that the formula, for Method 1 as expressed above, is wrong by a factor of 100.
Either the pickup needs to be expressed as a *proportion*, or there's a factor of 100 missing from the bottom (or else the heat really has finally got to me!)


For Method 2, the equilibrium cure, the factor seems fine, but it may save some people some unnecessary calculation to remark that the use of weights in pounds is not required. But it is required that the same units (such as grammes) be used throughout. What the unit happens to be doesn't matter, just that its exactly the same one. The thing is about proportions.

The same assumptions, and calculation, could equally well be made for nitrate, salt, or even sugar.

[Oddley]

dougal if you read the book they tell you to apply the % in the following form for say 10% use 0.10

but of course you can use:

lb nitrite � % pick-up � 1,000,000
------------------------------------------- = ppm
--------------lb pickle * 100

[dougal]

dougal if you read the book they tell you to apply the % in the following form for say 10% use 0.10

I'm glad its not a problem with my marbles!

But Oddley, I don't have the book.
Neither, I suspect do the vast majority of readers of this forum.
So such strange, non-standard (or wrong) things need to be made *clear*.

While I agree with the logic, I'm not sure that the arithmetic is being reproduced correctly.
...
Either the pickup needs to be expressed as a *proportion*, or there's a factor of 100 missing from the bottom (or else the heat really has finally got to me!)

0.10% is 1 part in 1000.
10% is one part in 10 as is 0.10 - but note, that last number is NOT a percentage, its a proportion.
Percentages and proportions ARE different, by a factor of 100 times.
And if the authors and publishers of this handbook have such scant regard for arithmetic as this, its really no wonder that the subject is veiled in such confusion and contradiction.

By applying the arithmetic correctly, hopefully the calculation methods may be useful.

[Oddley]

Dougal why don't you have the handbook? it is readily available HERE and I have posted the main link to it HERE

[dougal]

Sorry, Oddley. Thanks.
Turns out it was one of those things that I did already have, and had only quickly skimmed through, looking for principles rather than checking the details.

I don't find anything strange or novel in the logic of what they are proposing.

Just their cavalier way with describing numbers.

I find the section you quoted at Page 27 (out of 138) in the PDF {the page is numbered 22}.
On the previous page there is a worked example, in which they talk of "pumping to the 25% level" and use 0.25 in place of what they describe on the page previous to that one as "%pump".

I haven't found anywhere that they excuse or explain this cavalier (can't think of a better word) approach to accuracy in explaining their formulae.
On Page 11 of the PDF they show that they understand that "percent" means "parts per hundred". They could equally (in)accurately have described the 0.25 as "PPM pump". Its no more ppm than it is a percentage.

Oddley - I'm not blaming you. On the contrary, I congratulate you on digging this out, and on your readiness to question what has been said before.
However, I do think this mathematical woopsie is typical of the sloppy explanations generally offered in this field - which help to make it very much more confusing than it needs to be.

[deb]

Thanks Oddley.

I have bookmarked both threads to have a good read when time permits.